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Category: Life Science

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/

Why Non-Human Primates Don’t Speak Like Humans

Summary: Why are non-human primates unable to speak like humans? A widely-accepted theory associated it with their lack of vocal anatomy to produce human-like sounds. This was debunked, though, by recent studies upon recognizing vocal muscles similar to ours. It appears that non-human primates are speech-ready and yet do not speak still the way we do.

 

 

 

Perhaps, you have already seen one of those viral videos of pet dogs that seemingly muttered “I wuv (love) you”. Those dogs seemed to make a garbled speech, but still, they unfailingly fascinated people with their apparent “sweet talking“. Thus, one can truly wonder. If these dogs seem to be able to mutter a few, then, how come our closely-related apes and other primates are unable to do so? Even the more evolutionary-distant bird species, such as parakeets, mockingbirds, cockatoos, and other parrots possess the skills to mimic human language and yet our closely-related non-human primates were limited to merely grunts and hoots.

Non-human primates are believed to have no ability to speak or mimic human vocal sounds because of their vocal anatomy. However, a recent study debunked this widely-known theory.

 

 

 

Is it because of the non-human primates’ lack of vocal anatomy?

Why non-human primates are unable to speak has long been blamed on their vocal anatomy. A long-held theory explicates that monkeys and apes are incapable of, at least, imitating human speech sounds because their vocal tract is not that intricately flexible. In a paper published in “Science” in 1969, Philip H. Lieberman and others posited that non-human primates, particularly Rhesus (or macaque) monkeys (Macaca mulatta), were unable to speak like us because of vocal tract limitations. They went as far as to say that the ability for speech as we know it is a “… linguistic endowment …” exclusive to humans.1

A recent study debunked this widely-known theory. In the article, Muscles of the Apes, it referred to the study published in Frontiers in Ecology and Evolution wherein their findings refuted such long-held theory about apes lacking the muscles associated with the vocal communication (as well as bipedalism and facial expressions). These muscles were thought of as exclusive to humans. However, with the availability of more specimens to work on to, they found that certain apes did possess these muscles yet they did not put them to use as humans did. Apparently, the apes were likely speech-ready because they, too, possess the anatomy essential for generating human speech sounds.

 

 

 

Is it because of the non-human primates’ lack of exposure to humans?

Is human language nature- or nurture-driven? We are aware that our language is something that we learned and acquired as we grow. Perhaps, primates would be able to acquire it as well if they could be exposed profoundly to it, thus, came the Project Nim in 1973.

Project Nim was a controversial research. It was a Columbia University psychology experiment on a chimpanzee, named Nim Chimpsky. He was taken as a child from the wild to be raised in a common human household. The research aimed to see if the chimp would be able to acquire human-like behavior and language through nurture. The chimp did learn to convey through sign language but was not successful at speaking even a single word.2

 

 

 

Is it because of the non-human primate’s lack of the necessary brain wiring?

Another theory surfaces to explain why non-human primates are incapable of human speech and it has to do with brain wiring. Accordingly, while non-human primates (particularly, macaques) appear to be well equipped with a speech-ready vocal tract, they do not have the adequate brain wiring that regulates the vocal tract muscles to generate human-like speech sounds. They seem to lack the proper neural control on muscles on their vocal tract and as such are not able to configure them for speech.3

It is also postulated that there might be a molecular predisposition involved, for instance, the FOXP2 (forkhead box protein 2) gene.4 FOXP2 was the first gene identified to play a role in human speech and language development, thus, was called the “language gene“. It is located in chromosome 7 and is expressed in certain cells, including the brain. Mutation of this gene causes speech and language disorder in humans.

Non-human primates do not have the gift for human-like speech because they probably do not need one. Based on recent findings, they have the anatomical features similar to ours yet they produce vocal sounds different from ours. They do have a communication prowess that they use amongst them. It may be far different from ours but it is just as remarkable. Nevertheless, exploring the intricacies of language development could help us learn more about how humans diverged from our non-primate relatives and eventually acquired one of our own.

 

 

— written by Maria Victoria Gonzaga

 

 

 

References:
1 Lieberman, P. H., Klatt, D. H., & Wilson, W. H. (1969). Vocal Tract Limitations on the Vowel Repertoires of Rhesus Monkey and other Nonhuman Primates. Science 164: 1185-1187. Retrieved from
http://www.haskins.yale.edu/Reprints/HL0080.pdf
2 ‘Project Nim’: A Chimp’s Very Human, Very Sad Life. (2011). National Public Radio, Inc. Retrieved from https://www.npr.org/2011/07/20/138467156/project-nim-a-chimps-very-human-very-sad-life
3 Fitch, W. T., de Boer, B., Mathur, N., & Ghazanfar, A. A. (2016). Monkey vocal tracts are speech-ready. ScienceAdvances. Retrieved from http://advances.sciencemag.org/content/2/12/e1600723.full
4 Conger, C. (n.d.).Can chimpanzees learn human language? HowStuffWorks. Retrieved from https://animals.howstuffworks.com/mammals/chimps-learn-language.htm

A Neurobiological Approach to Understanding Human Intelligence

Is human intelligence measurable? … quantifiable? Perhaps, you came across this popular catchphrase purportedly quoted by the genius, Albert Einstein: “Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.” One of the most popular methods of measuring intelligence is by intelligence quotient (IQ) tests. The accuracy of the results is highly debatable though. These tests have long been criticized for being not all-inclusive, and therefore may not fully represent human intelligence.

 

 

 

Human intelligence – how the brain works

The brain is one of the most studied parts of the human body and yet scientists are still mystified as to how it completely works and how it hallmarks the uniqueness of human intelligence. An adult human brain is comprised of neurons and glial cells. While the glial cells are primarily for support, the neurons are essential for cell-to-cell communication, particularly for conducting nerve impulses. The neurons are excitable cells with specialized parts (e.g. soma, dendrites and axons), structures (e.g. synapses), and chemicals (e.g. neurotransmitters). In essence, the neuron generates nerve impulses that travel along the axon, resulting in the release of neurotransmitters that bind to the receptors of the dendrites of the target neuron. The ensuing effect may either be excitatory or inhibitory. The integration of these nerve impulses leads to the brain carrying out higher brain functions, such as language, speech, emotions, memory, learning, etc. The brain is truly a spectacular organ in charge of a mélange of tasks epitomizing human intelligence.

An illustration of the process of synaptic transmission in neurons

 

 

 

Human intelligence measured by IQ tests

IQ tests were devised to measure human intelligence based on the ability of an individual to generate answers that rely on reasoning and information, and how quickly. They are used in order to figure out if a person is capable of making quick, knowledgeable, and logical answers, especially in situations requiring immediate solutions. In educational settings, IQ tests help teachers predict which areas a student excels at and which ones a student would need extra help. However, making speculative conclusions based on IQ test results may lead to bias and wrong assumptions. For instance, predicting future success based on IQ or even on human intelligence is not as simple as it seems. It takes perseverance, passion, and sometimes, even luck. What a high IQ could point at is the person’s aptitude for certain realms of human intelligence.

 

 

 

Measures of human intelligence by neurobiological means

3D illustration of the human brain. (Credit: yodiyim)

Apart from IQ test-based measures, other methods have been designed to perceive and measure human intelligence. One of which is the integration of neurobiology. Researchers began to look at the structure of the brain and how it functions. Aki Nikolaidis, a neuroscientist, conducted a study with colleagues. Fluid intelligence was monitored through magnetic resonance spectroscopy on adult volunteers while taking IQ tests. Fluid intelligence is a form of intelligence primarily based not on stored knowledge but on the ability of a person to solve complex problems without prior information. In their study, they identified the specific parts of the brain that were active during fluid intelligence. They found that the predictor of fluid intelligence is located on the left frontal and parietal parts of the brain, independent of the brain size.1 Another recent study suggests that intelligence is inversely proportional to the number of dendrites the individual has. Accordingly, smarter people tend to have fewer brain dendrites, which implies that they have fewer connections between neurons in their cerebral cortex. In other words, the more intelligent a person is, the fewer brain wirings he or she needs for a brain function.2

 

 

 

How the brain works and how it is structured are just a few of the facets that researchers tap to understand human intelligence. Future research insights are crucial in order to methodically define what human intelligence is, and find ways, if not to boost it, keep it fairly functional even in the declining years.

 

 

 

— written by Maria Victoria Gonzaga

 

 

 

References:
1 Nikolaidis, A., Baniqued, P.L., Kranz, M.B., Scavuzzo, C.J., Barbey, A.K., Kramer, A.F., & Larsen, R.J. (2017). Multivariate Associations of Fluid Intelligence and NAA.
Cereb Cortex. 27(4):2607-2616. doi: 10.1093/cercor/bhw070.
2 Genç, E., Fraenz, C., Schlüter, C., Friedrich, P., Hossiep, R., Voelkle, M.C., Ling, J.M., Güntürkün, O., & Jung, R.E. (2018). Diffusion markers of dendritic density and arborization in gray matter predict differences in intelligence. Nature Communications, 9 (1) DOI: 10.1038/s41467-018-04268-8

What is a species – different approaches

What is a species? What does it take to be considered as a species? Ever since there has been an array of controversies surrounding the concise definition of species. Not everyone could merely agree on one. Multifarious approaches have been raised to answer that seemingly simple question. Conversely, the definition of a species has not been straightforward and consensus in this regard is indubitably far off.

 

 

 

Species as a biological concept

A taxonomist taking pictures of plant vouchers collected for further identification
(Credit: Fitryamandita, WikiMedia Commons under CC BY-SA 4.0 Int’l license)

 

Perhaps, all could agree that a species is the most basic unit or category in the biological classification of organisms.1 However, expanding that definition into specific criteria is indeed challenging. Using the biological approach of defining a species, it tells us that a species is an individual capable of mating with another of the same kind to produce fertile offspring. Based on this precept, individuals at the species level must not only be capable of mating with one another but they must also be capable of producing fertile offspring. This could be limiting if one would consider prehistoric and already extinct organisms. Assumptions based on this concept would, therefore, restrict the delineation of certain organisms at a species level.

 

 

 

Other approaches to interpreting a species

Apart from the biological approach, there are other insightful approaches that attempted to define a species. One of them relates to morphology. Accordingly, organisms at the species level would share common morphological characteristics. However, there are species that may be morphologically similar but would not be able to interbreed. Such is the case of Western meadowlark (Sturnella neglecta) and Eastern meadowlark (Sturnella magna) (see figure on the left)).Both of them belong to the same genus and look outwardly the same but are not capable of interbreeding.2 Another approach is one that is based on the genotypes of organisms. In this genetic approach, individuals at the species level have genomes that would indicate them as closely related. However, there are also limitations in this concept. For instance, polar bears (Ursus maritimus) and grizzly bears (Ursus arctos ssp.) are regarded as two different species despite being closely related based on their genome and on their ability to interbreed fertile offspring. There are other several approaches (e.g. ecological, evolutionary and phylogenetic) that are useful, however, similar to other approaches, they have limitations as well.

Western meadowlark (left) and Eastern meadowlark (right)
(Credits: USFWS Mountain-Prairie (left) and Jimfbleak (right), WikiMedia Commons under Attribution 2.0 Generic and CC BY-SA 3.0 Unported licenses, respectively)

 

 

 

Mathematical approach in defining a species

Thomas Donega, a bird expert, recently proposed a mathematical approach to ultimately address the issue on what is a species. In his paper published on Zookeys (an open access journal), he presented what he calls a universal mathematical formula to defining a species. 3 The formula measures the differences for multiple variables between two non-co-occurring populations and then comparing them to the same results for two related populations that co-occur together. When the differences of non-co-occuring pair exceed those of the good species pair, this could mean that the former may possibly be ranked as species. Otherwise, they may be a subspecies of the same species.4

 

 

 

Charles Darwin did mention the term ”species” in his book but he did not attempt restricting the term with a concise definition. Accordingly, he says, “No one definition has as yet satisfied all naturalists yet every naturalists knows vaguely what he means when he speaks of a species.” 5 Defining a species based on a clear set of criteria would depend largely on the available information. Inopportunely, what is considered as correct at this time may be challenged and eventually refuted as wrong in the future. Thus, applying all these approaches in defining a species is crucial but nonetheless must be flexible since the available information are prone to changes and rectifications sooner or later.

 

 

 

— written by Maria Victoria Gonzaga

 

 

 

References:
1 “Species”. (n.d.). Biology-Online.org . Retrieved from https://www.biology-online.org/dictionary/Species
2 TheBrainScoop. (2016). Youtube. Retrieved from https://www.youtube.com/watch?v=9fOfFlMe6ek&vl=en
3 Donegan, T.M. (2018). What is a species? A new universal method to measure differentiation and assess the taxonomic rank of allopatric populations, using continuous variables. ZooKeys 757: 1. DOI: 10.3897/zookeys.757.10965
4 Pensoft Publishers. (2018, May 10). What is a species? Bird expert develops a math formula to solve the problem. ScienceDaily. Retrieved from www.sciencedaily.com/releases/2018/05/180510115054.htm
5 “Online Variorum of Darwin’s Origin of Species: first British edition (1859), page 44.” (n.d.). Darwin-Online.org . Retrieved from http://darwin-online.org.uk/Variorum/1859/1859-44-c-1860.html

Molecular Basis of Temperature-Dependent Gender of Red-Eared Slider Turtle

Imagine a child inside a womb with a sex yet to be decided not by the pair of sex chromosomes but by the ambient temperature – well, that is how the sex of red-eared slider turtle (Trachemys scripta elegans) and other reptile species is determined. Whether the baby red-eared slider turtle develops into a male or female will depend on the ambient temperature of the nest. The eggs hatching from a cooler nest will be males whereas those in a warmer nest will be females. Nevertheless, scientists recently identified the molecular basis associated with the temperature-dependent sex determination in red-eared slider turtle.

 

 

 

Temperature-dependent sex determination in red-eared slider turtle

Red-eared slider turtle. (Photo by Greg Hume, WikiMedia Commons under CC BY-SA 3.0 license)

 

In humans, the sex of the offspring is determined by the pair of chromosomes inherited from the parents. At fertilization, the sex of the embryo is already determined. A female embryo would have two X chromosomes whereas a male embryo would have X and Y chromosomes. This mechanism of sex-determination is referred to as genotypic sex determination (GSD). This is also how the sex of many animals, including certain reptiles, is determined. Another mechanism is temperature-dependent sex-determination (TSD). It is when the temperature predicts the sex of the developing embryo. This is observed in many reptiles, such as crocodiles, alligators, and turtles. In red-eared slider turtle, for instance, their sex can be predicted depending on the incubation temperature. There is a critical period during which the embryonic development is thermosensitive. Red-eared slider turtle eggs hatching from cooler nests will all be males whereas those hatching from warmer nests will all be females.1

 

 

 

Molecular basis of sex-determination in red-eared slider turtle

Red-eared slider turtle laying an egg. (Photo by Nephets, WikiMedia Commons under CC BY-SA 3.0 license)

 

How the temperature causes the baby red-eared slider turtle to turn into male or female is a long-time enigma. The phenomenon of TSD was observed for more than 50 years ago and since then scientists have attempted to dig further into the molecular level of TSD. Are there genes involved in the process, and if there are, which genes? Researchers from Duke University and Zhejiang Wanli University in China published their study on red-eared slider turtle.2 Eggs incubated at 32 °C hatched as females while those incubated at a cooler temperature (26 °C) hatched as males. When they silenced the Kdm6b gene the eggs that supposedly would develop into males at a cooler temperature (26 °C) hatched as females. Knockdown of Kdm6b red-eared slider turtle babies developed ovaries rather than testes.

 

 

 

The molecular role of red-eared slider turtle Kdm6b gene

Kdm6b gene appears to be the key gene essential to turning on the switch of “maleness” in red-eared slider turtle. The activity of this gene is vital during the critical period of gonad development. It became more active at cooler incubation temperature and then “silent” at a warmer temperature. 1 The gene promotes directly the transcription of the male sex-determining gene, Dmrt1. It does so by coding for a protein that removes the trimethylation of the histone, H3K27, near the promoter region of Dmrt1. 2 The methyl tags of the histone repress DNA activity and therefore removing them would allow expression of the genes along the DNA molecule.

 

 

 

This study was unable to identify the temperature-sensing trigger since the Kdm6b and its protein were not inherently sensing temperature changes. 1 For now, the molecular basis of the temperature-dependent sex-determination in the red-eared slider turtle as described above has not reached completion. Nonetheless, what was currently discovered in the red-eared slider turtle may serve as a model to understand the underlying mechanism in other reptile species where the temperature is a major sex-determining factor.

 

 

 

— written by Maria Victoria Gonzaga

 

 

 

References:
1 Duke University. (2018). How turning down the heat makes a baby turtle male: Scientists start to crack 50-year puzzle of how temperature influences a hatchling’s sex. ScienceDaily. Retrieved from www.sciencedaily.com/releases/2018/05/180510203722.htm
2 Ge, C., Ye, J., Weber, C., Sun, W., Zhang, H., Zhou, Y., Cai, C., Qian, G., & Capel, B. (2018). The histone demethylase KDM6B regulates temperature-dependent sex determination in a turtle species. Science 360 (6389): 645.

Maternal and neonatal outcomes of respiratory failure during pregnancy

Respiratory failure is an outcome from inadequate gas exchange wherein arterial oxygen and carbon dioxide not at normal levels. A drop of oxygen is called hypoxemia while the rise in arterial carbon dioxide is hypercapnia. Respiratory failure includes abnormal blood gases, increased of breathing and increased respiratory rate. In obstetric patients a complicated conditions occurs resulting to various complications and several physiological changes.  That is why risk of complication in pregnancy with respiratory failure considered challenge for positive maternal and neonatal outcomes.

 

Causes in Maternal Respiratory failure

The main causes of respiratory failure were postpartum hemorrhage, peripartum period, preeclampsia and pneumonia during pregnancy. In which the oxygen reserve impairment during pregnancy causes fast desaturation leading to fetal hypoxia. Many of the patients showed improvement after delivery in partial pressure of arterial oxygen. But some exhibited high incidence of neonatal respiratory distress syndrome. Neonatal complications were commonly caused by sepsis and meconium aspiration syndrome as well as impairment in neurological development.

 

Acute respiratory distress syndrome is classified as mild to severe injuries from aspiration, trauma and multiple transfusions. It is also a condition of newborn having dyspnea with cyanosis that is often related to surfactant deficiency. However, preterm infant retinas showed incomplete retinal vascularization. On the other hand obstetric patients showed 74% having maternal respiratory failure complications while 25.4% to non-obstetric patients.

 

Indeed, early delivery might improve maternal oxygenation and reduce mortality rate. However maternal respiratory failure may not always improve after the delivery wherein deleterious sepsis and lung injury persist after delivery. Additionally a detailed examination is needed to follow up the neonates in the future. Using the risk categories whether normal, questionable and abnormal, if the mental developmental index is <70 then the neonates are suspected to have mental retardation.

 

Source: Prepared by Joan Tura from    Journal of the Formosan Medical  Association

Volume 117, Issue 5, May 2018, Pages 413-420

Physiotherapy breathing retraining for asthma: a randomised controlled trial

Asthma is a common global health problem that affects at least 18% of the population worldwide. Some of real life surveys show that all outcomes remain suboptimal with persisting symptoms and quality of life impairment. Many of the patients however, taking regular medication particularly corticosteroids and some self-management strategies. But in recent development it used breathing techniques to help control the symptoms of asthma. There were evidences for the effectiveness of self-management education as well as self-guided programmes to be accessed. In order, to have it conveniently and inexpensively to people with asthma and deliver standardized interventions. In 2012 US Agency for Healthcare Research and Quality concluded that non-pharmacological techniques can improve asthma symptoms and reduced medication.

 

Breathing retraining for Asthma patients

Breathing retraining exercise is recommended in evidence-based guidelines as possible adjuvant treatment for asthma patients. Based on pragmatic randomised trial the study reveals that three sessions of face-to-face physiotherapist improved the symptoms. Also the self-guided digital audiovisual program is considered as an acceptable intervention method. The current systematic and Cochrane review shows that breathing retraining therapy is an effective treatment with suitable trained physiotherapist.

 

Asthma is improved by the routine face-to-face method of breathing retraining exercise which eventually progress the quality of life impairment. In agreement with the previous research there were no significant changes in airway obstruction or inflammation observed. Therefore, breathing retraining provides a technique for coping better with asthma, but not disease modifying. That is why, with this intervention it will reduced the intake of anti-inflammatory medication and acts as an adjuvant.

 

The breathing retraining will allow patients how to adjust ones behavior and embed the techniques into daily lives.  Additionally, with the collaboration of Asthma UK a web-optimised version of the intervention for online used have been produced. In a way that such approaches indicates this evidence-based non-pharmacological intervention be offered to people with asthma despite current medication. There is a need to stress that this intervention is not a cure rather a means to improve quality of life.

 

Source: Prepared by Joan Tura from THE LANCET: Respiratory Medicine

Volume 6, Issue 1, January 2018, Pages 19-28

Men could go extinct? Y chromosome is slowly disappearing

Hold on to your seats, gentlemen — the male chromosome (Y chromosome) is slowly disappearing at a relatively fast rate and it might be gone completely in the future. This presumption is based on the genetic studies on the Y chromosome. It used to be genetically the same as the X chromosome. However, it has degenerated gradually, and now, it shriveled and became less relevant.

 

 

 

Y chromosome as male-determiner

Y Chromosome and DNA illustration. (Credit: Archaeogenetics, distributed by CC BY-SA 3.0 license)

 

Humans have two types of sex chromosomes: the X chromosome and the Y chromosome. Females have two X chromosomes whereas males have only one. Nonetheless, males have the Y chromosome that is passed on across generations from fathers to sons. In the XX/XY sex-determination system, the Y chromosome is the male-determining sex chromosome. Previously, the X chromosome was regarded as the sex-determiner. This conjecture, however, was eventually proven wrong when the SRY (sex-determining region Y) gene was identified on the male chromosome.1 This gene codes for the testis-determining factor, a protein that triggers testis development. Without this gene, testis fails to develop in males. There are few other genes present on the Y chromosome. However, compared with the X chromosome, the Y chromosome is relatively gene poor and the only highly notable gene on it is the SRY gene.

 

 

 

The disappearing Y chromosome debate

Going back in time, about 166 million years ago, the first mammals had a Y chromosome (called a proto-Y chromosome) that was genetically similar to and of the same size as the X chromosome.2 However, the male chromosome diminished into the short Y chromosome that it is now. The Y chromosome degenerates as it loses genes through time. Unlike the other chromosomes, the Y chromosome does not undergo genetic recombination. Based on the current speed of degeneration, the Y chromosome would likely have 4.6 million years left, which relatively speaking is not that long, considering the 3.5 billion years that life has existed on Earth.2 Some mammals, such as certain rodent species, have already lost their entire Y chromosome. 3 Some experts (referred to as the “leavers”) infer that this event would also happen to humans in the future. This notion was opposed by others (the “remainers”) who believe that the Y chromosome would not disappear completely because it has evolved corrective mechanisms that slow down and deter gene loss. Gene amplification (the acquisition of multiple gene copies) and the presence of palindromes (a sequence that reads the same, whether backward or forward, e.g. AGTGA) help mitigate gene loss.3

 

 

 

Men without Y chromosome in the future

Will men be extinct in the future?

 

If the Y chromosome ultimately disappears in the future, what will happen to men? Will there be men in the future? Experts believe that men will get by when that time comes. Men would still be around just as women have been perfectly fine without the Y chromosome. As for the SRY gene, it could move to a different chromosome. Nonetheless, the chromosome that would take this gene would be at risk of going through the same fate as that of the Y chromosome.3 The absence of SRY gene on the male chromosome is not new, however. In Swyer syndrome, the individual has a Y chromosome lacking the SRY gene and consequently fails to develop testis and other internal male organs. A person with this genetic condition is outwardly female but with a karyotype of a male (i.e. XY karyotype) .2

 

 

 

Further research on the degenerating male chromosome is essential to monitor the rate of gene loss on Y chromosome. One possible implication of the possible complete disappearance of Y chromosome is the impending necessity for more advanced reproductive modalities that can be applied artificially not just on humans but also on other mammals as reproduction by that time would ever hardly become natural.

 

 

 

— written by Maria Victoria Gonzaga

 

 

 

References:
1 “Y chromosome”. (n.d.). Biology-Online.org Dictionary. Retrieved from [https://biology-online.org/dictionary/Y_chromosome].
2 Griffin, D. & Ellis, P. (2018). The Y chromosome is disappearing – so what will happen to men?
Retrieved from https://theconversation.com/the-y-chromosome-is-disappearing-so-what-will-happen-to-men-90125
3 Griffin, D.K. Is the Y chromosome disappearing?—Both sides of the argument. Chromosome Res (2012) 20: 35. https://doi.org/10.1007/s10577-011-9252-1