Research Highlights: Study reveals what’s behind the king baboon spider’s painful bite


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Study reveals what’s behind the king baboon spider’s painful bite

  • King Baboon spider is a large African tarantula scientifically named Pelinobius muticus.
  • The spider usually has dark brown to orange coloration and lives in grasslands and shrublands of east Africa.
  • It has been reported that the spider’s bite can cause severe pain, swelling, itchiness, and muscle cramping.
  • Hyperalgesia, an abnormal increase sensitivity to pain, is the most well-known symptom after a bite from king baboon spider.
  • However, the molecular basis by which the venom induces the severe pain is not well understood.
  • Analysis of the venom revealed that a cysteine-rich peptide called δ/κ-theraphotoxin-Pm1a (δ/κ-TRTX-Pm1a) induced nocifensive behavior when injected into mice.
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  • Nocifensive behavior is the response of an animal to very unpleasant or painful stimuli.[1]
  • When a synthetic version of the peptide was introduced into the small dorsal root ganglion neurons, hyperexcitability was observed.
  • During the excessive excitation, tetrodotoxin-resistant sodium currents were enhanced, repolarization was impaired, and the threshold of action potential firing was lowered, all consistent with the severe pain associated with venomous bite.
  • The molecular mechanism of nociceptor sensitization by the cysteine-rich peptide involves several modes of actions over several ion channel targets.
  • The unselective targeting approach of the peptide may be an evolutionary adaptation in pain-causing defensive venom.
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Sources:

Rocio K. Finol-Urdaneta, Rebekah Ziegman, Zoltan Dekan, Jeffrey R. McArthur, Stewart Heitmann, Karen Luna-Ramirez, Han-Shen Tae, Alexander Mueller, Hana Starobova, Yanni K.-Y. Chin, Joshua S. Wingerd, Eivind A. B. Undheim, Ben Cristofori-Armstrong, Adam P. Hill, Volker Herzig, Glenn F. King, Irina Vetter, Lachlan D. Rash, David J. Adams, Paul F. Alewood Proceedings of the National Academy of Sciences Feb 2022, 119 (5) e2110932119; DOI: 10.1073/pnas.2110932119. https://www.pnas.org/content/119/5/e2110932119

[1] https://link.springer.com/referenceworkentry/10.1007%2F978-3-540-29805-2_2799


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Research Highlights: Microbes with high metabolic activity found in deep, hot subseafloor environment


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Microbes with high metabolic activity found in deep, hot subseafloor environment

  • About 25 percent of the world’s seabed sediment can be found at a depth where temperature is more than 80 °C.
  • Scientists previously proposed that 80 °C is the thermal barrier for life in the strata below the Earth’s surface.
  • Researchers discovered a population of methanogenic and sulfate-reducing organisms in deep buried marine sediment.
  • Methanogenic organisms produce methane as a metabolic byproduct in low oxygen conditions.[1]
  • Sulfate-reducing organisms can perform anaerobic respiration by using sulfate as terminal electron acceptor and reducing it to hydrogen sulfide.[2]
  • The IODP (International Ocean Discovery Program) Expedition 370 drilled and collected sediment cores in the Nankai Trough subduction zone just south of Japan.
  • The Nankai Trough subduction zone can reach temperatures of about 120 °C.
  • Subduction zone is the place where two plates of the Earth come together, one is found over the other.[3]
  • Researchers utilized a considerable suite of radiotracer experiments.
  • Radiotracers is a compound that contains a radioactive element and can be used to study the mechanism of chemical reactions.[4]
  • The small microbes discovered from the Nankai Trough subduction zone survived with high potential cell-specific rates of energy metabolism, similar to the rates in active surface microbes and laboratory cultures.
  • Researchers initially expected that the metabolic rates in the deep subseafloor will be extremely low.
  • The cells appear to expend almost all of their energy to repair damages from the high temperature.
  • At the same time, the cells are forced to balance between supporting themselves at a minimum level near the thermal barrier for life and a rich source of substrates and energy from the reactions of the sedimentary organic matter caused by the high temperature environment.

Sources:

Beulig, F., Schubert, F., Adhikari, R.R. et al. Rapid metabolism fosters microbial survival in the deep, hot subseafloor biosphere. Nat Commun 13, 312 (2022). https://doi.org/10.1038/s41467-021-27802-7

[1] https://en.wikipedia.org/wiki/Methanogen

[2] https://en.wikipedia.org/wiki/Sulfate-reducing_microorganism

[3] https://earthquake.usgs.gov/learn/glossary/?term=subduction%20zone

[4] https://www.iaea.org/topics/radiotracers


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Research Highlights: Broccoli Contains Compound That Can Kill Yeast


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green broccoli vegetable on brown wooden table
Photo by Pixabay on Pexels.com

Broccoli Contains Compound That Can Kill Yeast

  • Broccoli is a common edible green plant in the family Brassicaceae with all of the parts eaten as vegetable.[1]
  • A compound called 3,3’-diindolylmethane or DIM can be obtained from the digestion of indole-3-carbinol, found in broccoli.
  • DIM promotes cell death and autophagy in some human cancer.
  • Autophagy refers to the natural process of cell degradation by which unnecessary or non-functional cellular components are removed or recycled.
  • DIM extends lifespan in the yeast called Schizosaccharomyces pombe.
  • S. pombe, often called fission yeast, is a species of yeast used in traditional brewing.[3]
  • However, the way by which DIM promotes cell destruction in humans and extends lifespan in S. pombe are not very well understood.
  • Researchers show that DIM promotes cell destruction in log-phase cells which is dose-dependent.
  • .Log-phase is the period by which cells exponentially increase in number.
  • Researchers discovered that when high concentration of DIM was added, the cell’s nuclear envelope was disrupted and the chromosome tightly packed at an early stage.
  • On the other hand, when low concentration of DIM was added, cells were degraded but did not cause disruption on the nuclear envelope.
  • Cells defective in autophagy were more vulnerable to the low concentration of DIM which suggest the autophagic pathway contributes to the cell’s survival against DIM.
  • Additionally, researchers discovered that the cells with lem2 mutation are more sensitive to DIM.
  • Lem2 is a protein that regulates the size of the cell’s nuclear envelope.[2]
  • The nuclear envelope of cells with lem2 mutation was disrupted even at low DIM concentration.
  • The results highlight the importance of autophagic pathway and nuclear envelope integrity in maintaining cell viability during exposure to low DIM concentration.
  • Researchers speculated that the process of cell death and autophagy induce by DIM are conserved in humans and S. pombe.
  • Future studies are needed to understand more about the DIM being able to induce cell death and autophagy in humans and S. pombe.

Sources:

Emami P, Ueno M (2021) 3,3’-Diindolylmethane induces apoptosis and autophagy in fission yeast. PLoS ONE 16(12): e0255758. https://doi.org/10.1371/journal.pone.0255758

[1] https://en.wikipedia.org/wiki/Broccoli

[2] https://www.nature.com/articles/s41467-019-09623-x

[3] https://en.wikipedia.org/wiki/Schizosaccharomyces_pombe


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Research Highlights: Why Giant Pandas Remain Chubby Despite Low-Fat Diet?


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panda bear eating bamboo leaves in zoo
Photo by Alotrobo on Pexels.com

Why Giant Pandas Remain Chubby Despite Low-Fat Diet?

  • Changes in diet can lead to changes in the characteristics of gut microbiome.
  • However, the effects of gut microbiome characteristic changes remain unclear.
  • Researchers performed fecal microbiota transplantation or FMT of diet-specific feces from a giant panda into a germ-free mouse.
  • Researchers discovered that the bacterium Clostridium butyricum was greater in number when the giant panda ate more bamboo shoots than bamboo leaves.
  • C. butyricum is an anaerobic endospore-forming Gram-positive bacteria that produces butyrate.[1]
  • Eating more bamboo shoots was also correlated with significant increase in body mass.
  • After the stool transplant, the gut microbiome of the mouse resembled that of the giant panda.
  • Mice transplanted with stool microbiota from giant panda who ate more bamboo shoots grew faster and became more chubby.
  • Researchers discovered that butyrate extended the activity of a hepatic circadian gene which then increases the production of phospholipids.
  • Phospholipid is a fatty phosphorus-containing molecule that play important structural/metabolic roles in cells.[2]
  • The research study highlights the effects of seasonal shifts in the gut microbiome on host’s growth performance and allows an in-depth understanding of host-bacteria interactions in wild animals.

Sources:

Guangping Huang, Le Wang, Jian Li, Rong Hou, Meng Wang, Zhilin Wang, Qingyue Qu, Wenliang Zhou, Yonggang Nie, Yibo Hu, Yingjie Ma, Li Yan, Hong Wei, Fuwen Wei. Seasonal shift of the gut microbiome synchronizes host peripheral circadian rhythm for physiological adaptation to a low-fat diet in the giant panda. Cell Reports, 2022; 38 (3): 110203 DOI: 10.1016/j.celrep.2021.110203

[1] https://en.wikipedia.org/wiki/Clostridium_butyricum

[2] https://www.britannica.com/science/phospholipid


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Research Highlights: Evidence Shows Sixth Mass Extinction Is In Progress


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Evidence Shows Sixth Mass Extinction Is In Progress

  • The history of Earth’s biodiversity already went five Mass Extinctions.
  • All previous mass extinction events were all caused by natural phenomena.
  • Scientists claim that the Sixth Mass Extinction may be in progress, but this time caused by humans.
  • There are numerous signals suggesting the presence of biodiversity crisis which includes increasing extinction and decreasing abundances.
  • However, some speculated that these signals could not be the Sixth Mass Extinction.
  • Scientists usually use the IUCN Red List to support their stance on extinction.
  • Opponents of the theory of Sixth Mass Extinction argued that the rate of species loss is the same as the background extinction rate or the normal extinction rate.
  • Proponents suggest that the IUCN Red List is significantly biased and that the IUCN Red List mostly contains birds and mammals, and only a small portion of invertebrates have been evaluated against conservation criteria.
  • Proponents said that if we include estimates of the true number of invertebrate extinctions, species loss rate will exceed the background rate suggesting that the Sixth Mass Extinction is underway.
  • Researchers reviewed extinction rate according to realms.
  • Marine organisms face significant threats; however, marine biota crisis has not reached the same level as the non-marine biota crisis.
  • Island species have suffered more compared to continental species.
  • Although there are clues that plants may have suffered lower extinction rate, plants face similar conservation biases as with invertebrates.
  • Other extinction crisis believers thought that these evidences could be a new trajectory of evolution because humans are part of the natural world.
  • Humans are the only species capable of manipulating the Earth on a grand scale, and they let the current crisis to happen.
  • Numerous conservation efforts have been implemented at different levels; however, most are not species oriented and specific measures to protect every extant species individually are simply inconvenient.
  • Researchers encourage the nurturing of the innate human appreciation of biodiversity, but assert strongly that biodiversity is disappearing at an unprecedented rate.
  • With the mounting crisis, scientists should embrace the practices of preventive archaeology and document as many species before they go extinct.
  • Without crisis intervention, we could pave the way for the Earth to carry on its unfortunate trajectory towards a Sixth Mass Extinction.

Source:

Cowie, R. H., Bouchet, P., & Fontaine, B. (2022). The Sixth Mass Extinction: fact, fiction or speculation?. Biological reviews of the Cambridge Philosophical Society, 10.1111/brv.12816. Advance online publication. https://doi.org/10.1111/brv.12816


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Research Highlights: Pathogenic Fungus On Infected Dead Female Flies Fools Male Flies To Mate


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By © Hans Hillewaert, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=6665971

Pathogenic Fungus On Infected Dead Female Flies Fools Male Flies To Mate

  • The recognition species concept is an idea that a species is characterized by a unique fertilization system that restricts gene-flow with other species.[3]
  • When males and females meet, mating competition and mating preferences may lead to low-quality decisions during mating.
  • Certain flowers exploit the willingness of an insect to mate by using sexual imitation to attract pollinator insects.
  • Some obligate pathogens can increase their chance for transmission when their host mate with the opposite conspecific member.
  • Also, many parasites and pathogens control the behavior of their host to ensure dispersal.
  • However, it is not normal for pathogens to rely on both behavioral manipulation and sexual imitation.
  • Researchers from the University of Copenhagen and the Swedish University of Agricultural Sciences show that the fungus, Entomophthora muscae, produces a chemical compound that alters the cuticular hydrocarbons of dead infected female house fly.[4]
  • E. muscae is a pathogenic fungus that causes disease in adult flies and has been identified as a potential biological agent for many years.
  • Cuticular hydrocarbons are primarily a moisture-saving agent present on the surface of an insect and are thought to play a role in insect communication.[2]
  • When the fungus alters the cuticular hydrocarbons of the dead female house fly, the male house flies respond to the compound produced by the fungi and are attracted into mating with the dead female.
  • This allows a higher probability of the fungus to infect the male flies due to its close proximity.
  • The research highlights the evolution of an extended phenotypic trait that exploit male flies’ tendency to mate and benefit the fungus by changing the behavior of uninfected male house flies.

Related Video

Sources:

Naundrup, A., Bohman, B., Kwadha, C., Jensen, A., Becher, P., De Fine Licht, H. (2021). A pathogenic fungus uses volatiles to entice male flies into fatal matings with infected female cadavers. bioRxiv. 0.1101/2021.10.21.465334. https://www.biorxiv.org/content/10.1101/2021.10.21.465334v1

[2] Drijfhout, Falko & Kather, R. & Martin, Stephen. (2013). The role of cuticular hydrocarbons in insects. Behavioral and Chemical Ecology. 91-114. https://www.researchgate.net/publication/286303349_The_role_of_cuticular_hydrocarbons_in_insects

[3] https://www.oxfordreference.com/view/10.1093/oi/authority.20110803100408187

[4] https://biocontrol.entomology.cornell.edu/pathogens/entomophagamuscae.php


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Research Highlights: A Roundworm May Help Us Explain How We Perceive Gravity


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A Roundworm May Help Us Explain How We Perceive Gravity

  • Humans depend on gravity to determine orientation and maintain balance.
  • Gravity is important for life to exist on Earth.
  • However, the effect of gravity at the molecular level is poorly understood.
  • Among animals, anatomical differences are clearly evident but there is notable conservation across different animals at the molecular level.
  • Caenorhabditis elegans is appropriate for discovering genes that may help identify gravity sensing mechanism at the molecular level.
  • C. elegans is a free-living nematode or roundworm that lives in temperate soil environments.[1]
  • Half of C. elegans‘ genes are similar to humans which allows genetic studies to determine genes responsible for the similar traits in humans.
  • No study has been reported that C. elegans can detect the direction of gravity.
  • A team in Penn Engineering led by Professor Haim Bau and Professor David Raizen did a research that may explain the mystery of gravity sensing.
  • Researchers found that motile C. elegans swim in the direction of gravity while immobile C. elegans do not.
  • Regardless of the density of a solution, C. elegans position themselves downward.
  • Gravitaxis is not significantly affected by the animal’s gait but requires sensory cilia, dopamine transmission, as well as motility.
  • Gravitaxis is the directional movement of an organism in response to gravity.[2]
  • Gravitaxis does not require genes related to body touch response.
  • Gravitaxis is not mediated by passive forces like the hydrodynamics of the solutions where the C. elegans are swimming in.
  • The results suggest that gravitaxis is mediated by active neural processes that involve dopamine and sensor cilia.
  • C. elegans can be used as a genetically tractable system for research studies involving molecular and neural mechanisms of sensing gravity.

Related Video

Sources:

Chen, WL., Ko, H., Chuang, HS. et al. Caenorhabditis elegans exhibits positive gravitaxis. BMC Biol 19, 186 (2021). https://doi.org/10.1186/s12915-021-01119-9

https://phys.org/news/2021-09-microscopic-worm-gravity.html

[1] https://en.wikipedia.org/wiki/Caenorhabditis_elegans

[2] https://www.biologyonline.com/dictionary/gravitaxis


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