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Category: Life Science

Mitochondrial DNA not just from moms but also from dads?

If one wants to trace down lineage, that person could turn to the cell’s powerhouse, the mitochondrion. This organelle contains its own special set of DNA believed as inherited solely from mothers across generations.  Thus, looking at the mitochondrial DNA (by mtDNA genealogical DNA testing) could help track down lineage, and for this reason, help determine ancestral or familial connection. Recently though, a team of scientists reported that the mitochondrial DNA is not solely inherited from the mothers. New empirical evidence of biparental inheritance of mitochondrial DNA implicates the need to rectify the long-held notion that the inheritance of mitochondrial genome is exclusively matrilineal or female line.

 

 

Mitochondrial DNA

The mitochondrion (plural: mitochondria), reckoned as the powerhouse of the cell, generates metabolic energy, especially the form of adenosine triphosphate (ATP). And it does so through the process referred to as cellular respiration. Apart from that, the organelle is also described as semi-autonomous since it has its own genetic material distinct from that found in the nucleus. The nucleus contains more genes organized into chromosomes and in charge for almost all of the metabolic processes in the body. On the contrary, the genetic material in the mitochondrion – referred to as mitochondrial DNA – is relatively fewer in number. It carries the genetic code for the manufacturing of RNAs and proteins necessary to the various functions of the mitochondrion, such as energy production.

 

(Recent news on the evolutionary origin of mitochondria, read: Prokaryotic Ancestor of Mitochondria: on the hunt)

 

(You may also want to read: Mitochondrial DNA – hallmark of psychological stress)

 

Mitochondrial inheritance

In humans, the mitochondrial DNA is believed to be inherited solely from the mother. This notion stems from the events that happen at fertilization. The sperm contains on its neck a helix of mitochondria that power up the tail to swim toward the ovum. And when the sperm finally makes its way into the ovum, it leaves its neck and tail on the cell surface of the ovum. Mitochondria that are brought into the ovum would eventually be inactivated and disintegrated. Thus, the mitochondria in the ovum are the only ones that the zygote eventually inherits. A human ovum has an average of 200,000 mtDNA molecules.1 For this, certain traits and diseases involving mitochondrional DNA implicate maternal origin.

 

 

 

Inheritance of mitochondrial DNA– not exclusive

mitochondrial dna eve
The theory of Mitochondrial Eve is based on the exclusivity of human mitochondrial DNA inheritance to the female line, which when traced would lead to only one most recent woman, “Eve”. (Image credit: Ludela, Creative Commons Attribution-Share Alike 3.0 Unported)

 

The theory of Mitochondrial Eve holds that tracing the matrilineal lineage of all recent human beings would lead to all lines converging to one woman referred to as “Eve“. The theory is based on the exclusivity of human mitochondrial DNA inheritance to female line. Nevertheless, independent empirical findings and clinical studies challenge this precept.

 

For instance, Schwartz and Vissing2 reported the case of a 28-year-old man with mitochondrial myopathy. Accordingly, the patient had a mutation (a novel 2-bp mtDNA deletion in ND2 gene). Normally, the gene encodes for a subunit of the enzyme complex I of the mitochondrial respiratory chain. Thus, the faulty gene affected the production of such enzyme, which, in turn, led to the patient’s severe, lifelong exercise intolerance. Furhter, Schwartz and Vissing2 pointed out that the patient’s mitochondrial myopathy was paternal in origin.

 

Recently, a team of researchers observed paternal inheritance of mitochondrial DNA, but this time, on 17 people from three different families.3 They sequenced their mitochondrial DNAs and they discovered father-to-offspring transmission.

 

 

Conclusion

The mitochondrial DNA is said to be a mother’s legacy to her offspring. However, recent studies indicate that the father could also transmit it to his progeny. Somehow, paternal mitochondrial DNA gets into the ovum. Rather than disintegrated or inactivated, it gets expressed. Mitochondrial DNA from the fathers may not be as rare as once thought.  If more studies will corroborate soon, this could debunk Mitochondrial Eve theory. It might also render mtDNA genealogical DNA testing questionable. And, we may also need to start looking to the other side of our lineage to fathom hereditary diseases arising from faulty mitochondrial DNA.

 

 

— written by Maria Victoria Gonzaga

 

 

References:

 

1 Mitochondrial DNA. (2018). Biology-Online Dictionary. Retrieved from https://www.biology-online.org/dictionary/Mitochondrial_DNA

 

2 Schwartz, M. & Vissing, J. (2002). “Paternal Inheritance of Mitochondrial DNA”. New England Journal of Medicine. 347 (8): 576–580.

 

3 Luo, S.,  Valencia, C.A.,  Zhang, J., Lee, N., Slone, J., Gui, B., Wang, X.,  Li, Z.,  Dell, S., Brown, J., Chen, S.M.,  Chien, Y., Hwu, W., Fan, P.,  Wong, L.,  Atwal, P.S., & Huang, T. (2018). Biparental Inheritance of Mitochondrial DNA in Humans. Proceedings of the National Academy of Sciences 201810946. DOI:10.1073/pnas.1810946115

Pathobiology of allergy and its most severe form, anaphylaxis

When allergy season looms, some people with serious hypersensitivity to allergens tend to be apprehensive of what may come. Some would rather stay indoors than risking the odds of sucking up triggers that could instigate severe allergic reactions. Apart from triggers from the environment, other common factors for allergy include food, medication, certain toxins, venom from insect stings or bites, stress, and heredity. How does an allergy manifest? Which cells are involved in forming an allergic reaction?

 

 

 

The immune system

allergy
How does an allergy occur? The pathobiological mechanism involves several white blood cells that play a role in mounting an allergic reaction.

 

The immune system protects the body from foreign substances (generally referred to as antigens) that could pose a threat to our well-being.  It prevents harmful bacteria, viruses, parasites, etc. from invading and causing harm. The white blood cells (also called leukocytes) constantly scout for antigens in order to destroy or disable them. The white blood cells include lymphocytes, neutrophils, basophils, eosinophils, monocytes, macrophages, mast cells, and dendritic cells.

 

 

 

Allergy – overview

 

allergy pathway
The allergy pathway.
Image (by Sari Sabban) distributed under the CC 3.0 Unported license.

 

An allergy is a state of hypersensitivity of the immune system in response to an allergen (i.e. a substance capable of inciting an allergic reaction). In this regard, several white blood cells play a role in mounting an allergic reaction.

In summary, the entry of an allergen into the body triggers an antigen-presenting cell, such as a dendritic cell. The dendritic cell takes up the allergen, process it, and then present its epitopes through its MHC II receptor on its cell surface. It, then, migrates to a nearby lymph node, waiting for a T lymphocyte to recognize it.

Upon recognition, the T lymphocyte may differentiate into a Th2 cell (type 2 helper T cells), which is capable of activating B lymphocyte. B lymphocyte, when activated, matures into a plasma cell that could synthesize and release IgE antibody in the bloodstream. Some of the circulating IgE may bind to mast cell and basophil. Thus, re-entry of such allergen could incite the IgE on mast cells and basophils to recognize its epitope. In effect, this activates the mast cell or basophil to release inflammatory substances (e.g. histamine, cytokines, proteases, chemotactic factors) into the bloodstream.

 

 

 

Anaphylaxis – a dreadful allergic reaction

The allergic reaction mounted by the immune system is supposed to protect the body. However, the allergens perceived by the body as a threat are generally harmless. The body tends to overly react to the allergens, and so leads to symptoms. Histamine, for instance, brings about the common symptoms of allergy: pain, heat, swelling, erythema, and itchiness.

 

Anaphylaxis is the most severe form of allergic reaction. It can occur rapidly and it affects more than one body system, such as respiratory, cardiovascular, cutaneous, and gastrointestinal systems. It occurs as a result of the release of inflammatory substances from mast cells and basophils upon exposure to an allergen. Within minutes to an hour, symptoms could manifest as a red rash, swelling, wheezing, lowered blood pressure, and in severe cases, anaphylactic shock.

 

In the presence of breathing difficulties, racing heart, weak pulse, and/or a change in voice, the situation is precarious. It calls for an immediate medical attention.

 

Why does anaphylaxis occur? IgE-mediated anaphylaxis is the common form of anaphylaxis. Initial exposure to an allergen leads to the release of IgE so that re-exposure to the allergen leads to its identification and the eventual activation of mast cells and basophils.  Apart from immunologic factors, though, other causes of anaphylaxis are non-immunologic. For example, temperature (hot or cold), exercise, and vibration may cause anaphylaxis. In this case, IgE is not involved. Rather, these agents directly cause the mast cells and the basophils to degranulate.

 

 

 

Novel mechanism identified

Recently, a team of researchers1,2 found a novel mechanism that could explicate the hasty allergic reaction during anaphylaxis. They were first to uncover a mechanism involving the dendritic cells. Accordingly, a set of dendritic cells seem to “fish” allergens from the blood vessel using their dendrites. The dendritic cell near the blood vessel takes up the blood-borne allergen. Rather than initially processing it, and then presenting the epitope on its surface, it hands over the allergen inside a micro-vesicle to the adjacent mast cells.

 

Mast cells, unlike basophils that are in the bloodstream, are located in tissues, such as connective tissue. Thus, the question as to how the mast cells detect blood-borne allergen could be answered by the recent findings.

 

Rather than being internalized by the dendritic cells for processing, the allergen was merely taken into a micro-vesicle that budded off from the surface of dendritic cells. This, thus, saves time. It cuts the process, leading to a much rapid allergic reaction.

 

However, these findings were observed in mouse models. Therefore, the researchers have yet to observe if this novel mechanism also holds true on humans. If so, this could lead to possible therapeutic regulation of allergies, especially the most dreadful form, anaphylaxis.

 

 

— written by Maria Victoria Gonzaga

 

 

References:

1 Choi, H.W., Suwanpradid, J. Il, Kim, H., Staats, H. F., Haniffa, M., MacLeod, A.S., & Abraham, S. N.. (2018). Perivascular dendritic cells elicit anaphylaxis by relaying allergens to mast cells via microvesiclesScience 362 (6415): eaao0666 DOI: 1126/science.aao0666
2 Duke University Medical Center. (2018, November 8). Using mice, researchers identify how allergic shock occurs so quickly: A newly identified immune cell mines the blood for allergens to directly trigger inflammation. ScienceDaily. Retrieved November 22, 2018 from www.sciencedaily.com/releases/2018/11/181108142440.htm

 

First time! Human blood cell turned into a young sex cell

In essence, our body consists of two major types of cells – one group involved directly in reproducing sexually (called sex cells) and another group that are not (called somatic cells). In particular, the female sex cell is referred to as the ovum (also called egg cell) whereas the male sex cell, the sperm cell. The somatic cells, in turn, are the cells in the body that have varying functions, such as nourishing the sex cells as well as keeping the body thriving and functional.

 

 

 

Origin of sex cells

Our body produces sex cells through the process called gametogenesis. The process is essentially a step-by-step process of meiosis. Oogenesis (i.e. gametogenesis in females) takes place in the ovaries to produce ova or egg cells. In brevity, the oogonium (the female primordial germ cell) undergoes meiosis to produce four haploid egg cells. Conversely, spermatogenesis (i.e. gametogenesis in males) occurs in the testes to yield sperm cells. Quintessentially, the spermatogonium (the male primordial germ cell) will go through meiosis to give rise to four haploid sperm cells.

 

 

 

Sex cells vs somatic cells

In humans, a sex cell may be identified from a somatic cell in being a haploid cell. That means a sex cell would have half the number of chromosomes as that of a somatic cell. Hence, an egg cell or a sperm cell would have 23 chromosomes whereas a somatic cell would have 46. Haploidy in sex cells is important in order to maintain the chromosomal integrity in humans across generations.

 

At fertilization, the sperm cell and the egg cell unite to form a diploid cell (called zygote). The zygote, then, divides mitotically, giving rise to pluripotent stem cells. A pluripotent stem cell is a cell capable of giving rise to various precursors that eventually will acquire specific identity and physiological function via a process called differentiation. A differentiated cell means that the cell has matured and acquired a more specific role, for instance as a skin cell, a blood cell, a liver cell, etc.

 

 

 

Somatic cell converted to sex cell

sex cell
Soon, a somatic cell could be converted into human sex cells.
[Image credit: Karl-Ludwig Poggemann, Flicker.com, CC by 2.0]

 

Intrinsically, a human somatic cell that has “differentiated” could never become a sex cell just as a sex cell could neither become nor give rise to a somatic cell. However, this may no longer hold true in the years to come.

 

Japanese researchers have, for the first time, successfully converted a somatic cell into a sex cell precursor.1 In particular, they had successfully created an oogonium from a human blood cell. They turned blood cells into “induced pluripotent stem cells” (iPS).2 Essentially, the blood cells – turned iPS – appeared to have undergone “molecular amnesia”. It means they forget their initial identity. As a result, they could become any type of cell, even as a sex cell.

 

The researchers transformed human blood cells into oogonia (plural of oogonium). They did so by incubating them for four months in artificial ovaries derived from embryonic mouse cells. They retrieved promising results. Admittedly though, they acknowledged they are still in the early steps of a rather long journey of research. The oogonia, indeed precursors to egg cells, are, at this point, still young, and thereby, unfit for fertilization. The researchers have yet to induce them to become mature, fully differentiated egg cells. Nevertheless, they remain optimistic in having reached this point, and, undeniably, pioneered an important milestone.

 

 

 

 

Ethical issues

If, in the future, research on the conversion of a somatic cell into a sex cell pushes through to completion, it could lead to significant resolves to infertility issues. However, ethical concerns shall, likely, surface as well. For instance, a possibility could occur in time. A mere hair cell or a skin cell from an unsuspecting person could be turned into an egg or a sperm cell. And from there, an offspring could come into existence.

 

 

 

— written by Maria Victoria Gonzaga

 

 

References:

 

1 Yamashiro, C., Sasaki, K., Yabuta, Y., Kojima, Y., Nakamura, T., Okamoto, I., Yokobayashi, S., Murase, Y., Ishikura, Y., Shirane, K., Sasaki, H., Yamamoto, T., & Saitou, M. (2018 Oct 19).Generation of human oogonia from induced pluripotent stem cells in vitro. Science, 362(6412):356-360. doi: 10.1126/science.aat1674.

 

2 Solly, M. (2018 Sept. 24). Scientists create immature Human Eggs Out of Blood Cells For the First Time. Retrieved from [link]

 

“Mutualism factor” could explain why body does not attack normal flora

When sadness reeks in and you feel as if you are all by yourself, think again. That is because you are never alone. As a matter of fact, millions of microorganisms reside in our body day in and out. They are the normal flora. Our body is a world of microscopic living entities that inhabit our body without essentially causing a disease. Rather, they live in us in harmonious mutualism. Thus, our body is not ours alone. Hence, we can say we are not absolutely sterile from the moment we are born.

 

 

 

Normal flora

Typically, the body has about 1013 cells and harbors about 1014 bacteria.1 The multifarious yet specific genera of bacteria that predominate the body is referred to as the normal flora. In essence, the normal flora thrives in a host in a mutualistic lifestyle. The microbes take advantage from living stably in the body. In return, they confer benefits to the human host. For instance, their presence helps prevent other more harmful microbes from colonizing the host. Some of them biosynthesize products that the human body can use. Nevertheless, an immunocompromised host could suffer in cases when these bacteria became overwhelming in number, and thereby cause detectable harm, like infections or diseases.

 

 

 

Normal flora in the gut

normal flora in the gut
Escherichia coli, one of the many bacterial species of the normal flora in the human gut

 

Microbes that normally thrive in the gut are greater in density and diversity compared with those in other body parts. Nevertheless, they vary in density depending on the location in the gastrointestinal tract. For instance, the stomach harbors about 103 to 106/g of contents whereas the large bowel of the large intestine has about 109 to 1011/g of contents. The normal flora in the stomach has fewer normal microbial inhabitants due to its acidity. The ileum of the small intestine contains a moderate microbial number, i.e. 106 to 108/g of contents.1

 

Some of the various bacterial species of the normal gut flora includes the anaerobes, Enterococcus sp., Escherichia coli, Klebsiella sp., Lactobacillus sp., Candida sp., Streptococcus anginosus and other Streptococcus sp.. Some of these bacteria aid in the production of bile acid, vitamin K, and ammonia since they possess the necessary enzymes.

 

 

 

Coexistence

Certain normal gut bacteria can become pathogenic. They could cause a disease when opportunity presents such as when changes in their microbiota favor their growth. Be that as it may, a healthy individual would not be usually harmed by their presence. Thus, question arises — why our immune armies do not, by and large, act against the normal flora as aggressively as they would in the presence of more harmful pathogens.

 

Karen Guillemin, a professor of biology and one of the authors of a paper that appeared in a special edition of the journal eLife, was quoted3: “One of the major questions about how we coexist with our microbial inhabitants is why we don’t have a massive inflammatory response to the trillions of the bacteria inhabiting our guts.

 

 

 

“Mutualism factor”

Guillemin and her team of scientists reported that they uncovered a novel anti-inflammatory bacterial protein they referred to as Aeromonas immune modulator (AimA).  Accordingly, AimA is a protein produced by a common gut bacterium, Aeromonas sp., in the animal model, zebrafish.  The researchers found that AimA alleviated intestinal inflammation and extended the lifespan of the zebrafish from septic shock.2 Furthermore, they described it as an immune modulator that confers benefits to both bacteria and the zebrafish host.

 

The newly-discovered protein seems to be the first of its kind. Nevertheless, it is structurally similar to lipocalins, a class of proteins that, in humans, modulate inflammation. Based on their findings, the removal of this protein caused more intestinal inflammation in the host and the destruction of the normal Aeromonas gut bacterium. The reintroduction of AimA reverted to “normal”, i.e. the host, relieved from inflammation and Aeromonas’ typical density, restored. AimA appears to represent a new set of bacterial effector proteins. And, Guillemin referred to them as mutualism factors.3

 

Guillemin and her team postulate that many more of these mutualism factors exist even in humans, and yet to be found. These mutualism factors may have therapeutic potential for use in modulating inflammation especially in medical conditions such as sepsis and certain metabolic syndromes.

 

 

 

— written by Maria Victoria Gonzaga

 

 

References:

 

1 Davis, C. P. (1996). Normal Flora. In: Baron S, editor. Medical Microbiology. 4th edition. Galveston (TX): University of Texas Medical Branch at Galveston. Retrieved from [link]

2 Rolig, A. S., Sweeney, E. G., Kaye, L.E., DeSantis, M. D., Perkins, A., Banse, A. V., Hamilton, M.K., & Guillemin, K. (2018). A bacterial immunomodulatory protein with lipocalin-like domains facilitates host–bacteria mutualism in larval zebrafish. eLife. [link]

3 University of Oregon. (2018, November 6). Novel anti-inflammatory bacterial protein discovered: Newly discovered protein alleviates intestinal inflammation and septic shock in an animal model. ScienceDaily. Retrieved from [link]

Mosquitoes wiped out by CRISPR–Cas9 gene drive

Up to what extremes are we willing to take in order to ensure the survival of our species? Mosquitoes may be tiny and insignificant. But, they are one of the deadliest ectoparasites that ever lived. They do not just feed on our blood. They could even leave us with a gift – like a “Pandora’s box” of dreadful diseases. Thus, we took a long stride. We armed ourselves with various weapons against these obnoxious flying “bloodsuckers“. And recently, researchers from Imperial College London came up with a novel strategy aimed at destroying them at their molecular level — by hacking their DNA with CRISPR technology.

 

 

 

Little flies

mosquitoes
Mosquitoes belong to the Order Diptera of Class Insecta

 

Mosquitoes are winged insects that belong to the Order Diptera. Their name means “little fly“. They have slender bodies, a pair of wings, three pairs of legs, a proboscis, and a pair of feathery antennae. Their life stages include egg, larva, pupa, and adult. Gravid female lays eggs on the water surface. Larvae hatch from the eggs and grow into pupae. Pupae, also called wrigglers, develop further and then emerge from the water as adults.  Adult males feed on nectar whereas adult females feed on blood. The females have specialized proboscis that they use to puncture the skin of their host and to suck blood.

 

 

 

Pandora’s box

Female mosquitoes feed on the blood because they need nutrients from the blood when they produce eggs. Blood does not coagulate in their proboscis because of the presence of anticoagulants in their saliva. They inject saliva into the skin of the host. Inopportunely, the saliva also serves as the main route by which mosquitoes introduce pathogens into the host’s bloodstream. Some of the mosquito-borne diseases include yellow fever, dengue fever, chikungunya, malaria, lymphatic filariasis, tularemia, and Zika disease.

 

 

 

CRISPR, the game changer

CRISPR-Cas9 – a customizable tool that cuts and inserts small pieces of DNA at specific areas along a DNA strand. (Credit: Ernesto del Aguila III, National Human Genome Research Institute, NIH)

 

Scientists from Imperial College London had a breakthrough when they used CRISPR technology for a gene drive to completely wipe out a population of mosquitoes grown inside the lab.1

 

Short for clustered regularly interspaced short palindromic repeats, CRISPR is a gene-editing tool that scientists use to splice specific DNA targets and then replace them with a DNA that would yield the desired outcome.2

 

The researchers used CRISPR–Cas9 gene drive to suppress the population of caged Anopheles gambiae mosquitoes (human malarial vector). They modified the gene responsible for determining sex in male mosquitoes and turned the male gene dominant. Then, they added these “hacked’ mosquitoes to a caged population of unaltered male and female mosquitoes. The next generations of females could no longer lay eggs and could not bite. And by the eight generation, the population had no longer had females.3

 

 

Wiping out mosquitoes

Not all species of mosquitoes act as our straight foes. Thousands of mosquito species do not serve as vectors of diseases. Only a few hundreds (about 200) of them transmit human pathogens (e.g. Aedes aegypti, Anopheles spp.). Unfortunately, these few hundreds carry viruses, bacteria, protozoans, and helminthes that can cause serious, even fatal, diseases. Furthermore, current methods to eradicate them, e.g. spraying or fogging using insecticides, proved less ineffective since they developed resistance to such insecticides. Thus, the CRISPR technology could prove useful in this regard. However, the question remains: What will happen when these mosquitoes are completely eradicated from the face of the earth?

 

Obviously, humans reap directly the benefit of eradicating mosquito-borne diseases. However, it might also lead to an irrevocable ecological impact we could regret. Particularly in the food chain, loss of certain mosquito species could lead to the insufficiency of food for insectivores, such as birds and fish.  And over time, humans might eventually suffer as well from this jarring food-chain disturbance.

 

Mosquitoes have lived for so many million years. Do we have the right intent and purpose to deny them the right to live side by side with us? Could it be that we are in the verge of desperation? Definitely, we possess a powerful tool in our hands by the advent of CRISPR technology. However, what good of a purpose would it be if we use it solely for our own good?

 

 

— written by Maria Victoria Gonzaga

 

 

References:

1 Kyrou, K., Hammond, A. M., Galizi, R., Kranjc, N., Burt, A., Beaghton, A.K., Nolan, T. & Crisanti, A. (2018). A CRISPR–Cas9 gene drive targeting doublesex causes complete population suppression in caged Anopheles gambiae mosquitoes. Nature Biotechnology. Retrieved from https://www.nature.com/articles/nbt.4245
2 Gonzaga, M. V. (2018). CRISPR caused gene damage? Rise and pitfall of the gene-editor. Biology-Online.org. Retrieved from

CRISPR caused gene damage? Rise and pitfall of the gene-editor


3 Houser, K. (2018 Sept. 25). SCIENTISTS WIPED OUT A MOSQUITO POPULATION BY HACKING THEIR DNA WITH CRISPR. Futurism.com. Retrieved from https://futurism.com/the-byte/gene-drive-mosquitos-crispr?fbclid=IwAR13KtvXDAeOnL7tjTIOL0-E4Q59HHquKev73tiBfirxypfcNkxeZUNEi7A

Black-legged Kittiwakes: Sperm collection, characterization and morphology

Blacked-legged Kittiwakes are pelagic gulls that often feed on fish and macro-zooplankton at the ocean surface. They breed in colonies ranging from few to thousands of pairs which prominently observed in their open, sea-cliff nesting habitats. Blacked-legged Kittiwakes are the most popular models for research because they can be easily monitored and captured. They also considered as prime indicators of fluctuating conditions in marine ecosystem. The purpose of this research is to collect live sperm of blacked-legged Kittiwakes using a non-invasive method. Also, be able to provide information on suitable extenders and timing in relations to the breeding phenology. Additionally, it will offer informations to different disciplines including veterinary science, conservation biology, ecotoxicology and evolutionary biology.

 

Sperm collection of Blacked-legged Kittiwakes

Sperm of blacked-legged Kittiwakes were obtained by firmly massaging the lower back and the tail base of the male bird. Since, the researchers observed that during mating the male tend to wag their tails thus, releasing the sperm naturally. After massaging the handler lift the tail, clear the feathers around cloaca and gently squeeze the cloacal area. While doing this a capillary tube placed on the top of the cloaca to collect directly the translucent liquid. Then, verified directly to the laboratory under the microscope.

 

The result demonstrates a successful collection of live sperm under field condition of blacked-legged Kittiwakes for the first time. In which the researchers discovered two extenders suitable for maintaining the sperm however, undiluted sperm also performed well in terms of survival. Since, seminal fluids alone are sufficient enough to maintain the sperm alive. Though, the researchers still recommend using sperm extenders since it is necessary to dilute highly concentrated ejaculates. Also, extenders are necessary on sperm quality examination when comparing experimental groups and sperm production.

 

Blacked-legged Kittiwakes are strictly monogamous and stores semen inside their body unlike passerine birds that stores semen in seminal glomera. Interestingly, one has to keep in mind that sperm quality may vary seasonally. So, the researchers suggest that one should statistically account for this effects using date relative to laying eggs. Also the researchers recommends to target specific time window when the birds are about to copulate but not after copulation within a day.

 

Source: Prepared by Joan Tura from BMC Avian Research

Volume 9:24, 14 July 2018

Nutrients and bioactive potentials of green and red seaweeds

Seaweeds are macroscopic multicellular algae that have been used as food since ancient time. It was originated in Japan and then China particularly to the people who lived near the coastal areas. In addition to its nutritional value, seaweeds are rich source of structurally diverse bioactive compounds including polysaccharides, phlorotannins and pigments. Because of this, the demand  increases in the global trade wherein Korea is the major producers. In traditional Korean cuisines seaweeds used as soup, snack, pickle, vegetable and salad. Hence, this present research focuses on the edible green and red seaweeds found in Korea.

 

Green and Red Seaweeds Bioactive Compounds

Green seaweeds used to treat stomach disorders and hangovers because it contains 55% polysaccharides, 30% proteins, 13% ash and 1% lipids. It also have micro mineral such as calcium, manganese, iron, selenium, sodium, phosphate and potassium. Additionally, green seaweeds also used to treat wastewater and have significant medicinal value for rheumatism, high blood pressure and diabetes. In recent findings it has potentials bioactive properties to treat cancers and diabetes mellitus. Also it contains essentials oil to inhibit foodborne pathogens, anti-inflammatory, antioxidant and blood lipid reduction. Moreover, it has been used in traditional medicine for sunstroke, urinary diseases and hyperlipidemia. It is also useful to reduce eutrophication in mariculture waters that helps the survival rate productivity of shrimps and prawns.

 

Red seaweeds are the main source of hydrocolloids and contain vitamins A, B and C. It is also a rich source of carbohydrates particularly galactose and glucose. These red seaweeds are popularly known in agar production. And used as a raw material in bio-ethanol industry due to its high level of ethanol extraction efficiency. Likewise, both red and green seaweeds contain antioxidants properties due to its hydroxyl radical scavenging activity. That is responsible for neuro-protection against oxidative stress. In all, seaweeds have potential properties for anticancer, anti-diabetic, anti-obesity, anti-inflammatory, antimicrobial and anti-coagulant.

 

Therefore, seaweeds are vital source of food and medicine on different applications. The presences of secondary metabolites are potential to develop as functional materials due to its promising bioactive properties. Korea is one of the biggest consumers and producers wherein people mostly incorporate seaweeds on daily diets. This research suggests that increase consumption offers healthy benefits as well as utilization of seaweed materials as functional ingredients.

 

Source: Prepared by Joan Tura from  BMC Fisheries and Aquatic Sciences

Volume 21:19, 6 April 2018

 

Immune characterization of Breast Cancer Metastases

Breast cancer is the occurrence of lumps or thickening of the surrounding tissues of the breast mostly in women. Yet it also occurs rarely in men. It leads to the changes in shape and appearance of the breast. As well as the changes of skin like peeling, scaling and crusting of the surrounding nipples. Nowadays, extensive support for breast cancer awareness has helped generate advances in treatment and diagnosis. In which survival rates increased while the death rates continuously declining. Due to some factors such as personalized approach for treatment, early detection and have better knowledge of the disease. In this particular research a tumor-infiltrating lymphocytes has been evaluated to convey prognostic information of the breast cancer metastases. Assess its levels, immune composition and ligand expression in metastatic lesions.

 

Tumor-infiltrating lymphocytes as an Immunogenicity of Breast cancer

Evidences suggest the potential of tumor-infiltrating lymphocytes as biomarker in breast cancer metastatic stage. Even at onset of disease it proves as prognostic biomarker in human epidermal growth factor receptor positive with breast cancer. 94 patients have been studied retrospectively with metastatic breast cancer. Younger women showed significant lowered tumor-infiltrating lymphocytes compared to older patients above 50 years of age. Generally tumor-infiltrating lymphocytes are low but have been recognized significantly at high level with patients having this disease. Moreover, previous reports indicate that at secondary or recurrence of disease a lower tumor-infiltrating lymphocytes level occurs.

 

Analysis of the characteristics of tumor immune infiltrate differs across metastatic sites. It also suggests that cutaneous tissues might harbor permissive immune microenvironment for tumor growth. In which immune heterogeneity across metastatic sites need to be explored because it is relevant in treatment and immunotherapy. Other factors that are significant to tumor-infiltrating lymphocytes composition are those patients treated with multiple lines of chemotherapy. Indeed, heavily pretreated patients might have an impaired antitumor cytotoxic activity of the immune system.

 

Therefore, tumor-infiltrating lymphocytes showed strong prognostic value in breast cancer patients. Further examinations of its relevance as biomarker reflect a general activation of the immune system. Thus, it indicates that tumor-infiltrating lymphocytes is a simple method that effectively appreciates the immune activation status of tissue negative tumor. Certainly, given the availability of standardized method of the assessment, this immune marker is technically simple and clinically reliable. Finally, tumor-infiltrating lymphocytes provide novel hypothesis-generating data with regards to immune composition and complex interplay with breast cancer metastatic setting.

 

Source: Prepared by Joan Tura from Springer BMC Breast Cancer Research

Volume 20:62, 22 June 2018

Thanatosis – Faking Death To Escape Doom

Thanatosis — pretending to be dead — is one of the best strategies that certain wild animals came up with in order to survive. Since the prey is usually inferior to its predator, it must use wit to its advantage. When all else seems futile, thanatosis seems the only way to go.

 

 

 

Thanatosis – what is it?

Thanatosis, colloquially speaking, is playing dead. It is a behavior manifested by certain animals to deceive their predators. Running away could have been the best option but when cornered the animal has to make a hasty decision between fighting back and feigning death. In certain situations, thanatosis works; it proves to be more useful than battling it out in the rubble. Not only does it make the animal save up precious energy but it also buys time to figure out a route with higher chances of escape. Instead of forcing a way out, thanatosis applies trickery, i.e. by deceptively submitting to the opponent only to seize the right opportunity to escape when it comes.

 

 

 

Thanatosis and predation

Several animals use thanatosis to facilitate escape. For instance, a threatened Eastern hognose snake (Heterodon platirhinos) initially displays an intimidating pose. It raises its head off the ground, hiss, and strike. When the threat display fails, the snake engages its opponent to a dramatic performance of thanatosis. As if poisoned and about to die, the snake rolls onto its back, shudders, and hangs out its tongue. Not only will it look dead… it will also smell dead when it releases a foul-smelling fluid from its cloaca.1

The phrase “playing possum” stems from the thanatosis behavior of Virginia opossum (Didelphis virginiana). When it senses extreme danger, it appears dead similar to a comatose state. Out of great fear, it lies on its side with eyes and mouth open and tongue hanging out. It releases a greenish fluid that smells rotten through its anus. This thanatosis display causes the deterrence of predators. A prey that died suddenly seemed like something went wrong and eating it might lead to trouble.

“playing possum”

 

Unfortunately, there are also predators that utilize thanatosis to deceive preys. Cichlids (Nimbochromis sp.), for instance, act dead by not moving so that an unsuspecting prey will be lured closer, and therefore get a better chance of capturing it.

 

 

 

Thanatosis to evade sexual cannibalism

Apart from evading a predator, certain animals use thanatosis to deceive an aggressive female to mate with. Mating in some spiders can be a dangerous activity. The female spiders attack the male spiders to feed on them after sex. This devouring of another individual of the same species before, during, or after copulation is called sexual cannibalism. While there are spiders that welcome it (read: The Amazing Spider Dads), other spiders attempt to circumvent it. For instance, the male wolf spiders perform thanatosis to avoid ending up as a meal after copulating.2 The male nursery web spiders (Pisaura mirabilis) also resort to thanatosis but apart from it they also do nuptial gift-giving during courtship rituals. In a study by Hansen et al.3, the male spiders that played dead had more success in mating with hostile females and stayed alive right after.

 

 

 

In the wild, resorting to thanatosis to survive is not uncommon. At the edge of demise, these animals enact the greatest performance of their lives. They appear to have died a disturbing death to mislead predators. Who prefers a spoiled meat? Most predators want their meal fresh; hence, they may no longer find a prey looking repulsive and smelling putrid appetizing. Thanatosis proves its invaluable use as an anti-predation strategy. Besides that, animals playing dead for sex and evading cannibalism demonstrate that thanatosis is tantamount to surviving — die to live!

 

 

— written by Maria Victoria Gonzaga

 

 

 

References:
FrankSnakes. (2012). Eastern Hognose (Heterodon platirhinos) Playing Dead. Retrieved from https://www.youtube.com/watch?v=UxbT2acTsrM
2 Seriously Science. (2016). Male spiders play dead to avoid “sexual cannibalism.” Retrieved from http://blogs.discovermagazine.com/seriouslyscience/2016/05/26/5406/
3 Hansen, L.S., Gonzales, S. F., Toft, S., & Bilde, T. (2008).Thanatosis as an adaptive male mating strategy in the nuptial gift–giving spider Pisaura mirabilis. Behavioral Ecology, Volume 19, Issue 3, 1 May 2008, Pages 546–551. Retrieved from https://academic.oup.com/beheco/article/19/3/546/185057

The Amazing Spider Dads

Humans are not the only fathers capable of giving it all for the sake of their progeny. The animal kingdom is teeming with fathers that are downright heroes.  For instance, male redbacks and dark fishing spiders would voluntarily throw themselves into the clutches of their mated female and eaten… never again to procreate or see the light of the ensuing days. This seems disturbing. How could mating be evolutionary costly for these unfortunate yet amazing spidey dads?

 

 

 

Sexual cannibalism of spider fathers

Sexual cannibalism. (Credit: Kumon, Flickr)

 

The mating of spiders in which the female eventually devours the male is one the most fascinating animal couplings. In this case, male spiders that engage in the rituals of courtship and copulation are likely dead fathers. Literally hungry for more, the females consume their mates in an act called sexual cannibalism. The devouring of another individual of the same species could occur before, during, or after copulation. The female spiders are usually the sexual cannibal, perhaps, because they are often larger than their male counterparts, and so, more physically dominating. Cannibal female spiders are often hostile and unenthused to mate. Thus, male spiders ought to be valiant to approach and fancy them with their moves. An impending death may be too much of a price to pay but these hopeless romantics are willing just so they can be fathers to their mate’s soon-to-be spiderlings.

 

 

 

Spider Fathers avoiding sexual cannibalism

Sexual cannibalism in spiders is real. However, not all spider dads end up harmed after mating.  Many male spiders, in fact, do not end up in the females’ gut. Not all female black widow spiders consume the fathers of their prospective spiderlings. Thus, the notion that all black widow females are sexual cannibals (hence, the “widow” on their name) is a misconception.1 There are also male spiders that came up with their own tricks. One fantabulous example is to play dead. By appearing stiff dead, male wolf spiders avoid ending up as a palatable snack after copulation.2  The apparent death trick is called thanatosis.

(Read: Thanatosis – faking death to escape doom)

 

 

Altruistic Spider Fathers

While certain spiders dodge sexual cannibalism, there are those that do not just welcome it but also incite it. These male spiders are the quintessential altruistic spider fathers. Male redbacks (Latrodectus hasseltii), for instance, encourage adult females to engage in sexual cannibalism. After inseminating the adult female, the male somersaults to bring his body close to her mouthparts like a cue saying “eat me now”. The female spider spits gut juice, and then feeds on him. If lucky enough to live after that, he returns to her, filling her with more sperm, plus a nutritious “meal”.  Eventually, he dies by succumbing to his injuries from slow cannibalism. Another example is the male dark fishing spider (Dolomedes tenebrosus). As if a befitting sacrifice to his female, the spider curls up with no hesitation. Thus, one may wonder: “Why would these male spiders sacrifice their life for a one-time sex?” It seems unsound and evolutionary counter-productive. Research3 on dark fishing spiders implicated that cannibalism improved offspring survival. Females that ate their spiderlings’ fathers had more surviving offspring than those that did not. The spider dads seem to possess unknown components that significantly boosted their offspring size, fitness, and survival.

Redback spider. (Credit: Ryan Wick, Flickr)

Dark fishing spider. (Credit: Charles de Mille-Isles, Flickr)

 

 

 

 

In essence, the self-sacrificing behavior of these spider fathers is a manifestation of how ready they are to die for the sake of their progeny. With the assurance that their genes are passed on to their offspring, they served a remarkable purpose as befitting fathers to their spiderlings even if it means acceding to sexual cannibalism.

 

 

 

— written by Maria Victoria Gonzaga

 

 

 

References:
1 Crawford, R. (2015). Myth: Black widows eat their mates. Retrieved from http://www.burkemuseum.org/blog/myth-black-widows-eat-their-mates
2 Seriously Science. (2016). Male spiders play dead to avoid “sexual cannibalism.” Retrieved from http://blogs.discovermagazine.com/seriouslyscience/2016/05/26/5406/
3 Choi, C. (2016). Journal Club: Self-sacrificing male spiders assist in their own cannibalism to aid offspring. Retrieved from http://blog.pnas.org/2016/10/journal-club-self-sacrificing-male-spiders-assist-in-their-own-cannibalism-to-aid-offspring/