Opening a can of centipedes: new insights into mechanisms of body segmentation

The search for a common developmental genetic mechanism of body segmentation appears to become more difficult, and more interesting, as new segmented organisms are added to the roster. Recent work in this journal by Brena and Akam on segmentation of the geophilomorph centipede Strigamia maritima, an arthropod distantly related to the standard insect models, contains developmental and evolutionary surprises that highlight the importance of a wider sampling of phyla.See research article: http://www.biomedcentral.com/1741-7007/11/112     

Proteasome inhibition,the pursuit of new cancer therapeutics,and the adaptor molecule p130Cas

Current interest in proteasome inhibitors for cancer therapy has stimulated considerable research efforts to identify the molecular pathway to their cytotoxicity with a view to identifying the mechanisms of sensitivity and resistance as well as informing the development of new drugs. Zhao and Vuori describe this month in BMC Biology experiments indicating a novel role of the adaptor protein p130Cas in sensitivity to apoptosis induced not only by proteasome inhibitors but also by the unrelated drug doxorubicin.See research article: http://www.biomedcentral.com/1741-7007/9/73     

A novel deconvolution method for modeling UDP-N-acetyl-D-glucosamine biosynthetic pathways based on 13C mass isotopologue profiles under non-steady-state conditions

This article is a response to Wang and Luo. See correspondence article http://www.biomedcentral.com/1741-7007/10/30/ [WEBCITE] and the original research article http://www.biomedcentral.com/1741-7007/9/24 [WEBCITE].     

Segmental structure in banded mongoose calls

In complex animal vocalizations, such as bird or whale song, a great variety of songs can be produced via rearrangements of a smaller set of 'syllables', known as 'phonological syntax' or 'phonocoding' However, food or alarm calls, which function as referential signals, were previously thought to lack such combinatorial structure. A new study of calls in the banded mongoose Mungos mungo provides the first evidence of phonocoding at the level of single calls. The first portion of the call provides cues to the identity of the caller, and the second part encodes its current activity. This provides the first example known in animals of something akin to the consonants and vowels of human speech.See research article http://www.biomedcentral.com/1741-7007/10/97     

The Rabs: A family at the root of metazoan evolution

This paper is a response to Pecinka A, Fang W, Rehmsmeier M, Levy AA, Mittelsten Scheid, O: Polyploidization increases meiotic recombination frequency in Arabidopsis. BMC Biology 2011, 9:24. See research article at http://www.biomedcentral.com/1741-7007/9/24     

Tackling thermosensation with multidimensional phenotyping

Ring species, in which two different forms coexist in one region while being connected by a long chain of interbreeding populations encircling a geographic barrier, provide clear demonstrations of the evolution of one species into two. Known ring species are rare, but now Monahan et al. propose an intriguing new approach to discovering them: focus first on geography to find potential barriers. See research article http://www.biomedcentral.com/1741-7007/10/20     

Difficult phylogenetic questions: more data, maybe; better methods, certainly

The combination of molecular sequence data and bioinformatics has revolutionized phylogenetic inference over the past decade, vastly increasing the scope of the evolutionary trees that we are able to infer. A recent paper in BMC Biology describing a new phylogenomic pipeline to help automate the inference of evolutionary trees from public sequence databases provides another important tool in our efforts to derive the Tree of Life. See research article: http://www.biomedcentral.com/1741-7007/9/55     

Single-nucleotide polymorphism,linkage disequilibrium and geographic structure in the malaria parasite <Emphasis Type="Italic">Plasmodium vivax</Emphasis>: prospects for genome-wide association studies

Background

The ideal malaria parasite populations for initial mapping of genomic regions contributing to phenotypes such as drug resistance and virulence, through genome-wide association studies, are those with high genetic diversity, allowing for numerous informative markers, and rare meiotic recombination, allowing for strong linkage disequilibrium (LD) between markers and phenotype-determining loci. However, levels of genetic diversity and LD in field populations of the major human malaria parasite P. vivax remain little characterized.

Results

We examined single-nucleotide polymorphisms (SNPs) and LD patterns across a 100-kb chromosome segment of P. vivax in 238 field isolates from areas of low to moderate malaria endemicity in South America and Asia, where LD tends to be more extensive than in holoendemic populations, and in two monkey-adapted strains (Salvador-I, from El Salvador, and Belem, from Brazil). We found varying levels of SNP diversity and LD across populations, with the highest diversity and strongest LD in the area of lowest malaria transmission. We found several clusters of contiguous markers with rare meiotic recombination and characterized a relatively conserved haplotype structure among populations, suggesting the existence of recombination hotspots in the genome region analyzed. Both silent and nonsynonymous SNPs revealed substantial between-population differentiation, which accounted for ~40% of the overall genetic diversity observed. Although parasites clustered according to their continental origin, we found evidence for substructure within the Brazilian population of P. vivax. We also explored between-population differentiation patterns revealed by loci putatively affected by natural selection and found marked geographic variation in frequencies of nucleotide substitutions at the pvmdr-1 locus, putatively associated with drug resistance.

Conclusion

These findings support the feasibility of genome-wide association studies in carefully selected populations of P. vivax, using relatively low densities of markers, but underscore the risk of false positives caused by population structure at both local and regional levels.See commentary: http://www.biomedcentral.com/1741-7007/8/90

     

From taxonomic literature to cybertaxonomic content

In the ubiquitin-proteasome system, a subset of ubiquitylated proteins requires the AAA+ ATPase p97 (also known as VCP or Cdc48) for extraction from membranes or protein complexes before delivery to the proteasome for degradation. Diverse ubiquitin adapters are known to link p97 to its client proteins, but two recent papers on the adapter protein UBXD7, including one by Bandau et al. in BMC Biology, suggest that rather than simply linking p97 to ubiquitylated proteins, this adapter may be essential to coordinate ubiquitylation and p97-mediated extraction of the proteasome substrate. These findings add to growing indications of richly diverse roles of adapters in p97-mediated signaling functions. See research article: http://www.biomedcentral.com/1741-7007/10/36     

Hsp90 depletion goes wild

Hsp90 reveals phenotypic variation in the laboratory, but is Hsp90 depletion important in the wild? Recent work from Chen and Wagner in BMC Evolutionary Biology has discovered a naturally occurring Drosophila allele that downregulates Hsp90, creating sensitivity to cryptic genetic variation. Laboratory studies suggest that the exact magnitude of Hsp90 downregulation is important. Extreme Hsp90 depletion might reactivate transposable elements and/or induce aneuploidy, in addition to revealing cryptic genetic variation.See research article http://wwww.biomedcentral.com/1471-2148/12/25     

In search of noise-induced bimodality

Many biological studies are carried out on large populations of cells, often in order to obtain enough material to make measurements. However, we now know that noise is endemic in biological systems and this results in cell-to-cell variability in what appears to be a population of identical cells. Although often neglected, this noise can have a dramatic effect on system responses to environmental cues with significant and often counter-intuitive biological outcomes. A recent study in BMC Systems Biology provides an example of this, documenting a bimodal distribution of activated extracellular signal-regulated kinase in a population of cells exposed to epidermal growth factor and demonstrating that the observed bimodality of the response is induced purely by noise.See research article: http://www.biomedcentral.com/1752-0509/6/109     

Interspecific responses of wild African carnivores to odour of 3-mercapto-3-methylbutanol,a component of wildcat and leopard urine

The scent of 3-mercapto-3-methylbutanol (3-M-3-MB), a volatile component of leopard (Panthera pardus) and domestic cat (Felis silvestris catus) urine, released at about 10 ng/s from slow-release dispensers, elicited scent-marking from African civet (Civettictis civetta), small-spotted genet (Genetta genetta) and slender mongoose (Galerella sanguinea), as well as African wildcat (F. s. cafra). A female leopard was apparently repelled by the scent. The scent-marking and scent-rubbing by species other than African wildcats and leopards were unexpected and have important implications for the design of studies to investigate chemical communication between wild mammals and the use of camera traps to estimate animal numbers. Videos showing the behaviours referred to in this article are available at; http://www.momo-p.com/showdetail-e.php?movieid=momo161223fs01a; http://www.momo-p.com/showdetail-e.php?movieid=momo161223gs01a; http://www.momo-p.com/showdetail-e.php?movieid=momo161223gg01a.     

The Year of the Wisent

Delving into European prehistory, two recent studies analyze ancient DNA from bison species depicted by our ancestors on the walls of their caves. The DNA tells a story of migrations driven by climate change but leaves some mystery clouding the genetic descent and climate preference of the still-extant wisent, otherwise known as the European bison.See research articles: https://bmcbiol.biomedcentral.com/articles/10.1186/s12915-016-0317-7 http://www.nature.com/articles/ncomms13158     

Darcin: a male pheromone that stimulates female memory and sexual attraction to an individual male's odour

Background

Among invertebrates, specific pheromones elicit inherent (fixed) behavioural responses to coordinate social behaviours such as sexual recognition and attraction. By contrast, the much more complex social odours of mammals provide a broad range of information about the individual owner and stimulate individual-specific responses that are modulated by learning. How do mammals use such odours to coordinate important social interactions such as sexual attraction while allowing for individual-specific choice? We hypothesized that male mouse urine contains a specific pheromonal component that invokes inherent sexual attraction to the scent and which also stimulates female memory and conditions sexual attraction to the airborne odours of an individual scent owner associated with this pheromone.

Results

Using wild-stock house mice to ensure natural responses that generalize across individual genomes, we identify a single atypical male-specific major urinary protein (MUP) of mass 18893Da that invokes a female's inherent sexual attraction to male compared to female urinary scent. Attraction to this protein pheromone, which we named darcin, was as strong as the attraction to intact male urine. Importantly, contact with darcin also stimulated a strong learned attraction to the associated airborne urinary odour of an individual male, such that, subsequently, females were attracted to the airborne scent of that specific individual but not to that of other males.

Conclusions

This involatile protein is a mammalian male sex pheromone that stimulates a flexible response to individual-specific odours through associative learning and memory, allowing female sexual attraction to be inherent but selective towards particular males. This 'darcin effect' offers a new system to investigate the neural basis of individual-specific memories in the brain and give new insights into the regulation of behaviour in complex social mammals.See associated Commentary http://www.biomedcentral.com/1741-7007/8/71

     

Analyses of density-dependent effects are needed to understand how and when <Emphasis Type="Italic">Wolbachia</Emphasis> can control dengue vectors

Releases of Wolbachia-infected mosquitoes have been shown to be an effective method of controlling Aedes aegypti, the main vector of dengue fever, in Australia. A study in BMC Biology from Penelope Hancock and others shows that incorporation of density-dependent effects into population models can provide major improvements in understanding how and when the infected populations can become established.See research article: https://bmcbiol.biomedcentral.com/articles/10.1186/s12915-016-0319-5.     

Is sex necessary?

Fungal sexual reproductive modes have markedly high diversity and plasticity, and asexual species have been hypothesized to arise frequently from sexual fungal species. A recent study on the red yeasts provides further support for the notion that sexual ancestors may give rise to shorter-lived asexual species. However, presumed asexual species may also be cryptically sexual, as revealed by other recent studies.See research article: http://www.biomedcentral.com/1471-2148/11/249     

Optimization and control in bacterial Lag phase

The lag phase of bacterial growth is important from a medical and food safety perspective, but difficult to study due to the low density and metabolic rate of cells. A new study by Alon and colleagues reveals that the gene expression program during early lag phase prioritizes carbon source utilization enzymes over genes responsible for biomass accumulation. This cellular strategy ultimately maximizes growth, making the best long-term use of the new nutrient-rich environment.See research article: http://www.biomedcentral.com/1752-0509/7/136     

Lateral gene transfer in eukaryotes: tip of the iceberg or of the ice cube?

Lateral gene transfer (LGT) is the transmission of genes, sometimes across species barriers, outwith the classic vertical inheritance from parent to offspring. LGT is recognized as an important phenomenon that has shaped the genomes and biology of prokaryotes. Whether LGT in eukaryotes is important and widespread remains controversial. A study in BMC Biology concludes that LGT in eukaryotes is neither continuous nor prevalent and suggests a rule of thumb for judging when apparent LGT may reflect contamination.See research article: http://bmcbiol.biomedcentral.com/articles/10.1186/s12915-016-0315-9.     

Mating and aggressive behaviour of <Emphasis Type="Italic">Brachyrhaphis olomina</Emphasis> (Cyprinodontiformes: Poeciliidae)

Despite the increasing interest in the use of intromittent male genitalia and coercive mating behaviour in poeciliids, detailed studies of the mating behaviour of most species in this family are lacking. We describe here the mating and aggressive behaviours of Brachyrhaphis olomina, and correlate them with the condition of the female’s ovum and embryos (immature, mature and pregnant). B. olomina performed a wide range of aggressive (sidle spread, tail beating, coordinate) and mating behaviours (approximation, touch, lateral display, touch-lateral display). Some behaviours (e.g. tail beating) are shared with other poeciliids, but two sexual behaviours (touch and lateral display) and one aggressive (coordinate) behaviour may be unique to B. olomina and were not reported in a previous study. Differences in male behaviour when paired with a female with mature ovum (more mating displays, no agonistic movements) suggest that males detect the female’s reproductive condition from some distance. The distinctive nature of mating behaviour in B. olomina highlights the importance of studying different species to have a better understanding of the evolution of mating and aggressive behaviours in poeciliids. Digital video images related to the article are available at http://www.momo-p.com/showdetail-e.php?movieid=momo170720bo01a, http://www.momo-p.com/showdetail-e.php?movieid=momo170720bo02a and http://www.momo-p.com/showdetail-e.php?movieid=momo170720bo03a.     

The scent of your enemy is my friend? The acquisition of large carnivore scent by a smaller carnivore

Scent marking is critical to intraspecific communication in many mammal species, but little is known regarding its role in communication among different species. We used 4 years of motion-triggered video to document the use of scent marking areas—termed “community scrapes”—by pumas (Puma concolor) (http://www.momo-p.com/showdetail-e.php?movieid=momo160812pc01a) and other carnivore species. We found that gray foxes (Urocyon cinereoargenteus) routinely rubbed their cheeks on puma scrapes (http://www.momo-p.com/showdetail-e.php?movieid=momo160812uc01a), and tested a series of hypotheses to determine its function. We found that gray foxes selected puma scrapes over other objects, and cheek rubbing by foxes was also correlated with how recently a puma had visited the scrape, suggesting that foxes were intent upon accumulating fresh puma scent. Cheek rubbing by foxes was not correlated with their breeding season or with how recently another fox had visited the site. Finally we found a cascading pattern in the occurrence of pumas, coyotes (Canis latrans) and gray foxes at community scrapes, suggesting that gray foxes may use puma scent to deter predation. This is the first published study to find evidence of a subordinate species using the scent of a dominant species to communicate with heterospecifics. The behavioral cascade we found in scent marking patterns also suggests that scent marking could be a mechanism that impacts the distribution and abundance of species. Additional videos pertaining to this article include http://www.momo-p.com/showdetail-e.php?movieid=momo160812uc02a, and http://www.momo-p.com/showdetail-e.php?movieid=momo160812uc03a.