Is reduced female survival after mating a by-product of male-male competition in the dung fly <Emphasis Type="Italic">Sepsis cynipsea</Emphasis>?

Background  

In a number of species males damage females during copulation, but the reasons for this remain unclear. It may be that males are trying to manipulate female mating behaviour or their life histories. Alternatively, damage may be a side-effect of male-male competition. In the black scavenger or dung fly Sepsis cynipsea (Diptera: Sepsidae) mating reduces female survival, apparently because males wound females during copulation. However, this damage does not seem to relate to attempted manipulation of female reproduction by males. Here we tested the hypothesis that harming females during mating is an incidental by-product of characters favoured during pre-copulatory male-male competition. We assessed whether males and their sons vary genetically in their ability to obtain matings and harm females, and whether more successful males were also more damaging. We did this by ranking males' mating success in paired competitions across several females whose longevity under starvation was subsequently measured.     

Nicotinamide riboside kinase structures reveal new pathways to NAD+

The eukaryotic nicotinamide riboside kinase (Nrk) pathway, which is induced in response to nerve damage and promotes replicative life span in yeast, converts nicotinamide riboside to nicotinamide adenine dinucleotide (NAD⁺) by phosphorylation and adenylylation. Crystal structures of human Nrk1 bound to nucleoside and nucleotide substrates and products revealed an enzyme structurally similar to Rossmann fold metabolite kinases and allowed the identification of active site residues, which were shown to be essential for human Nrk1 and Nrk2 activity in vivo. Although the structures account for the 500-fold discrimination between nicotinamide riboside and pyrimidine nucleosides, no enzyme feature was identified to recognize the distinctive carboxamide group of nicotinamide riboside. Indeed, nicotinic acid riboside is a specific substrate of human Nrk enzymes and is utilized in yeast in a novel biosynthetic pathway that depends on Nrk and NAD⁺ synthetase. Additionally, nicotinic acid riboside is utilized in vivo by Urh1, Pnp1, and Preiss-Handler salvage. Thus, crystal structures of Nrk1 led to the identification of new pathways to NAD⁺.     

Nicotinamide Riboside Kinase Structures Reveal New Pathways to NAD+

The eukaryotic nicotinamide riboside kinase (Nrk) pathway, which is induced in response to nerve damage and promotes replicative life span in yeast, converts nicotinamide riboside to nicotinamide adenine dinucleotide (NAD⁺) by phosphorylation and adenylylation. Crystal structures of human Nrk1 bound to nucleoside and nucleotide substrates and products revealed an enzyme structurally similar to Rossmann fold metabolite kinases and allowed the identification of active site residues, which were shown to be essential for human Nrk1 and Nrk2 activity in vivo. Although the structures account for the 500-fold discrimination between nicotinamide riboside and pyrimidine nucleosides, no enzyme feature was identified to recognize the distinctive carboxamide group of nicotinamide riboside. Indeed, nicotinic acid riboside is a specific substrate of human Nrk enzymes and is utilized in yeast in a novel biosynthetic pathway that depends on Nrk and NAD⁺ synthetase. Additionally, nicotinic acid riboside is utilized in vivo by Urh1, Pnp1, and Preiss-Handler salvage. Thus, crystal structures of Nrk1 led to the identification of new pathways to NAD⁺.     

Reconstructing the evolution of umbonal sculptures in the Unionida

‘Umbonal sculptures’ of freshwater mussels (Unionida), which ornament the early ontogenetic shell, have long been used for species identification. Specificity of these sculptures to higher taxonomic levels and their value for phylogenetic reconstruction are still under considerable scientific debate. In particular, the distribution of beak sculpture morphotypes across the unionoid phylogeny and, consequently, evolution of this character remain poorly understood. Based on an examination of 187 taxa, covering five of the six extant unionoid families, this study presents a new model of character evolution of umbonal sculptures in the order. Ten morphotypes were recognized and conceptualized into the cladistic characters sculpture presence and category. Optimization of sculpture presence on two recent hypotheses of palaeoheterodont phylogenetic relationships using the program Mesquite indicates a sculptured common ancestor of the extant Unionida, with multiple losses of the umbonal ornament occurring subsequently within the clade. Reconstruction of changes in sculpture category is ambiguous and demonstrates the need for further research into the evolutionary relationships of freshwater mussels in general and of their early ontogenetic sculptures in particular. Ambiguity is reduced in analyses applying a model with unequal costs of transformation between character states, which was derived from observations on intermediate forms and polymorphisms. These analyses suggest ‘V‐shaped’ or ‘nodulous’ sculpture as the plesiomorphic sculptural category for Unionida. The relatively low levels of homoplasy inferred for V‐shaped, pseudo‐radial and double‐looped sculptures suggest that these types may comprise useful guides to relationships within Unionida. The high degree of homoplasy of W‐shaped, pseudo‐concentric, wrinkled and single‐looped sculptures, on the other hand, renders these sculpture types less fit for such purposes.     

One-electron oxidation in the degradation of creosote polycyclic aromatic hydrocarbons by Phanerochaete chrysosporium.

The abilities of whole cultures of Phanerochaete chrysosporium and P. chrysosporium manganese peroxidase-mediated lipid peroxidation reactions to degrade the polycyclic aromatic hydrocarbons (PAHs) found in creosote were studied. The disappearance of 12 three- to six-ring PAHs occurred in both systems. Both in vivo and in vitro, the disappearance of all PAHs was found to be very strongly correlated with ionization potential. This was true even for compounds beyond the ionization potential thresholds of lignin peroxidase and Mn3+. Deviations from this correlation were seen in the cases of PAHs which are susceptible to radical addition reactions. These results thus begin to clarify the mechanisms of non-lignin peroxidase-labile PAH degradation in the manganese peroxidase-lipid peroxidation system and provide further evidence for the ability of this system to explain the in vivo oxidation of these compounds.     

Global diversity of freshwater mussels (Mollusca, Bivalvia) in freshwater

The term freshwater bivalve is very inclusive and not very informative. There are representatives of at least 19 families that have at least one representative living in freshwater. This suggests at least 14 different invasions of freshwater. At least nine families have small to large radiations in the freshwater environment: Corbiculidae, Sphaeriidae, Dreissenidae, and the unioniforme families: Hyriidae, Margaritiferidae, Unionidae, Etheriidae, Iridinidae, and Mycetopodidae. The unioniforme families contain at least 180 genera and about 800 species. This order is characterized by the unique parasitic larval stage on the gills, fins or the body of a particular host fish. This order of freshwater bivalves is suffering a very high rate of extinction, with about 37 species considered presumed extinct in North America alone. The level of endangerment and extinction facing these animals is primarily the result of habitat destruction or modification. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

Ultrasonic pregnancy diagnosis in the camel

Application of ultrasound for pregnancy diagnosis has been tested and evaluated in 15 Iranian camels (Camelus dromedarius), all of which ultimately calved. Transabdominal examinations were unsuccessful, while intrapelvic application resulted in the reception of sounds characteristic for foetal life, similar to those found in other domestic animals. Signals of foetal heart, pulse of umbilical vessels and uterine artery as well as foetal movement could be recognized as distinct sounds and have been recorded for further studies. An attempt was made to verify the findings of the ultrasonic diagnosis through rectal palpation. The ultrasonic technique resulted in 12 correct and three incorrect diagnoses.     

Molecular evolution of the mammalian ribosomal protein gene, RPS14

Ribosomal protein S14 genes (RPS14) in eukaryotic species from protozoa to primates exhibit dramatically different intron-exon structures yet share homologous polypeptide-coding sequences. To recognize common features of RPS14 gene architectures in closely related mammalian species and to evaluate similarities in their noncoding DNA sequences, we isolated the intron-containing S14 locus from Chinese hamster ovary (CHO) cell DNA by using a PCR strategy and compared it with human RPS14. We found that rodent and primate S14 genes are composed of identical protein-coding exons interrupted by introns at four conserved DNA sites. However, the structures of corresponding CHO and human RPS14 introns differ significantly. Nonetheless, individual intron splice donor, splice acceptor, and upstream flanking motifs have been conserved within mammalian S14 homologues as well as within RPS14 gene fragments PCR amplified from other vertebrate genera (birds and bony fish). Our data indicate that noncoding, intronic DNA sequences within highly conserved, single-copy ribosomal protein genes are useful molecular landmarks for phylogenetic analysis of closely related vertebrate species.