Scientists Trace Origin and Evolution of GPCR Kinases

20 03 2012

G protein-coupled receptor (GPCR) kinases (GRKs) are important in regulating many signaling pathways in the bodies of animals.  Both under and over regulation of GRKs has been implicated in a variety of human illnesses, including heart disease, Parkinson’s disease, and depression.

Reporting in an article published on March 19, in the online journal PLoS One (Public Library of Science One), a team of scientists from the United States has traced the origins and evolution of these kinases.  Based on their study, the team concludes that GPCRs are very old, having appeared before the rise of Metazoa and expanded rapidly among true metazoans.  They hypothesize that this rapid expansion was the result of the need for quick signalling adjustments in fast-moving animals.  They note that this “lifestyle requires the ability to reset and re-engage the environmental sensors frequently, which calls for [a] rapid shut-off mechanism.  A dedicated system for quick deactivation of GPCR may have been one of the factors profoundly determining the metazoan lifestyle.”  For the full paper, see here.

G Protein-Coupled Receptor Kinase

Crystal structure of G protein coupled receptor kinase 1 (GRK1) bound to ATP (Credit: Image is from Wikipedia Commons and is by the Jmol development team. It is used under a GNU Free License.)





New Genus and Species of Pterosaur Discovered in Morocco

27 05 2010

An international team of paleontologists has discovered a new genus and species of pterosaur in the Kem Kem formation of southeastern Morocco.  Published May 26, in the online journal Public Library of Science One (PLoS One), it is named Alanqa saharica, and according to the authors is “the first clear evidence for the presence of azhdarchids in Gondwana at the start of the Late Cretaceous.”

The remains discovered at the site, along with other specimens now ascribed to the new species, represent animals with wingspans of approximately three to four meters.  However, a vertebra discovered that probably belongs to the same species indicates that a wingspan of six meters was possible.

The discovery adds to our knowledge of pterosaurs from Africa, which has been severely limited until recently, and even now is represented only by a number of fragmentary specimens.

The article can be read in its entirety at the following link: 
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0010875.





Simulation Study Indicates “Non-Negligible” Natural Selection on Alleles Affecting Human Longevity and Late-Life Disease

5 04 2010

This article, by Fotios Drenos and Thomas B. L. Kirkwood, both of the Institute for Ageing and Health at Newcastle University, Newcastle Upon Tyne, Tyne, United Kingdom, that appeared on March 31, 2010, in the online journal PloS One, uses computer simulation to show that the effects of natural selection on genes affecting health in old age can be significant.  Below is the abstract from the article.  To read the complete article, please see the following URL:  http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0010022.

Abstract

It is often claimed that genes affecting health in old age, such as cardiovascular and Alzheimer diseases, are beyond the reach of natural selection. We show in a simulation study based on known genetic (apolipoprotein E) and non-genetic risk factors (gender, diet, smoking, alcohol, exercise) that, because there is a statistical distribution of ages at which these genes exert their influence on morbidity and mortality, the effects of selection are in fact non-negligible. A gradual increase with each generation of the ε2 and ε3 alleles of the gene at the expense of the ε4 allele was predicted from the model. The ε2 allele frequency was found to increase slightly more rapidly than that for ε3, although there was no statistically significant difference between the two. Our result may explain the recent evolutionary history of the epsilon 2, 3 and 4 alleles of the apolipoprotein E gene and has wider relevance for genes affecting human longevity.





Scientists use Mitochondrial DNA to Identify Recently Diverged Mouse Lemur Lineages

5 04 2010
This image is copyrighted under the creative commons attribution license by Weisrock D.W., Rasoloarison R.M., Fiorentino I., Ralison J.M., Goodman S.M., et al. (2010) for the article “Delimiting Species without Nuclear Monophyly in Madagascar's Mouse Lemurs”. Appearing in PLoS ONE 5(3): e9883. doi:10.1371/journal.pone.0009883.

The island of Madagascar, showing the areas of sampling used in this study.

An international team of researchers has used mitochondrial DNA (mtDNA) to help distinguish between a group of Madagascar Mouse Lemurs who have recently begun to diverge.

One of the issues associated with delineating species that have recently diverged from common ancestors is that often there has not been sufficient time for the usual cues of speciation, such as morphological differences, reproductive isolation, and monophyly within the gene tree to have become settled and readily evident.  Writing in the online journal, PLoS One, seven scientists from the United States, Germany, and Madagascar used multiple lines of evidence from mtDNA and nuclear DNA (nDNA) to identify “cryptically diverged” population-level mouse lemur lineages from throughout Madagascar.  It is believed to represent the most thorough sample of mouse lemur species ever conducted.

The result was the identification of a large number of geographically-defined clades.  These were strongly supported by the initial mtDNA evidence, as well as additionally supported by nDNA patterns.  The clades thus identified, are also supported by population divergence estimates based on genealogical exclusivity estimates.  The paper concludes that “Mouse lemur lineage diversity is reflected in both a geographically fine-scaled pattern of population divergence within established and geographically widespread taxa, as well as newly resolved patterns of micro-endemism revealed through expanded field sampling into previously poorly and well-sampled regions.”

For more information, please see the original article at the following URL: http://www.plosone.org/article/info:doi/10.1371/journal.pone.0009883





Energy Expenditure and Body Composition in Two Sympatric Lemurs does NOT Support Theories Accounting for Unusual Socio-Ecological Traits and Life History Features

27 03 2010
This image is from Wikimedia Commons and is in the Public Domain

Lemur Catta, also known as the Ring-tailed Lemur

In an article published March 25, in the Online journal PLoS one, researchers present evidence showing no support for the theory that energy conservation behaviors and mechanisms are the result of evolutionary adaptation in response to unusual socio-ecological traits and life history features of those species.

Following is the abstract from the article.  For the complete article, please see the following URL:
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0009860.

Abstract

Background

Evolutionary theories that account for the unusual socio-ecological traits and life history features of group-living prosimians, compared with other primates, predict behavioral and physiological mechanisms to conserve energy. Low energy output and possible fattening mechanisms are expected, as either an adaptive response to drastic seasonal fluctuations of food supplies in Madagascar, or persisting traits from previously nocturnal hypometabolic ancestors. Free ranging ring-tailed lemurs (Lemur catta) and brown lemurs (Eulemur sp.) of southern Madagascar have different socio-ecological characteristics which allow a test of these theories: Both gregarious primates have a phytophagous diet but different circadian activity rhythms, degree of arboreality, social systems, and slightly different body size.

Methodology and Results

Daily total energy expenditure and body composition were measured in the field with the doubly labeled water procedure. High body fat content was observed at the end of the rainy season, which supports the notion that individuals need to attain a sufficient physical condition prior to the long dry season. However, ring-tailed lemurs exhibited lower water flux rates and energy expenditure than brown lemurs after controlling for body mass differences. The difference was interpreted to reflect higher efficiency for coping with seasonally low quality foods and water scarcity. Daily energy expenditure of both species was much less than the field metabolic rates predicted by various scaling relationships found across mammals.

Discussion

We argue that low energy output in these species is mainly accounted for by low basal metabolic rate and reflects adaptation to harsh, unpredictable environments. The absence of observed sex differences in body weight, fat content, and daily energy expenditure converge with earlier investigations of physical activity levels in ring-tailed lemurs to suggest the absence of a relationship between energy constraints and the evolution of female dominance over males among lemurs. Nevertheless, additional seasonal data are required to provide a definitive conclusion.