Dynamic mate-searching tactic allows female satin bowerbirds Ptilonorhynchus violaceus to reduce searching

Females can maximize the benefits of mate choice by finding high-quality mates while using search tactics that limit the costs of searching for mates. Mate-searching models indicate that specific search tactics would best optimize this trade-off under different conditions. These models do not, however, consider that females may use information from previous years to improve mate searching and reduce search costs in subsequent years. We followed female satin bowerbirds Ptilonorhynchus violaceus during mate searching and reconstructed their search patterns. We found that females who chose very attractive males typically mated with the same male in the following year, resulting in these females sampling fewer males than those who switched mates. In contrast, females who mated with less attractive males typically rejected their previous mates and searched longer for more attractive mates in the following mating season. A potential cost to mate searching is suggested by the observed increase in the likelihood of force-copulation attempts from marauding males with increased searching. Our results suggest that by using past experiences to adjust their search tactics, females may obtain high-quality mates while limiting search costs. These results emphasize the need to consider historical effects in studies of sexual selection, especially for long-lived species with stable display sites.     

Kin selection may contribute to lek evolution and trait introgression across an avian hybrid zone

Understanding the mechanism(s) that favour cooperation among individuals competing for the same resources provides direct insights into the evolution of grouping behaviour. In a hybrid zone between golden-/yellow-collared (Manacus vitellinus) and white-collared (Manacus candei) manakins, males form aggregations composed of white and yellow males solely to attract females ('mixed leks'). Previous work shows that yellow males in these mixed leks experience a clear mating advantage over white males, resulting in the preferential introgression of yellow plumage allele(s) into the white species. However, the yellow male mating advantage only occurs in mixed leks with high frequencies of yellow males, and only a few of these males probably mate. Hence, it remains unclear why unsuccessful males join leks. Here, we used microsatellite markers to estimate pairwise relatedness among males within and between leks to test whether indirect genetic benefits of helping kin ('kin selection') can promote grouping. We found that yellow males are significantly more related to each other within than between leks, while relatedness among white males did not differ within and between leks. This suggests that yellow males may indirectly enhance their own reproductive success by preferentially lekking with relatives because yellow plumage is under positive frequency-dependent selection (positive FDS). Our results are consistent with the hypothesis that kin selection may promote grouping and facilitate positive FDS for yellow males, mediating the movement of yellow plumage across this hybrid zone.     

Signaling via histamine receptors in cat duodenal smooth muscle cells

Histamine produced concentration-dependent contractions in cat duodenal smooth muscle cells that were obtained by enzymatic digestion of smooth muscle with collagenase F. Pyrilamine, an H1 receptor antagonist, inhibited the contractile response while famotidine, an H2 receptor antagonist, augmented it. In cells with selectively preserved H1 receptors, produced by pretreatment with pyrilamine followed by inactivation of all unprotected receptors with N-ethylmaleimide, histamine-induced contraction was significantly augmented as compared with control cells. Pertussis toxin (PTX) had no effect on contraction, suggesting that the H1 receptor is coupled to a PTX-insensitive G protein. Gi2, Gi3, Go, Gs, and Gq subunits were present in cat duodenum, and histamine-induced contraction was inhibited by Gq antibody after cell permeabilization. Neomycin, a PLC inhibitor, inhibited the histamine-induced cell contraction, but not rhoCMB, a PLD inhibitor, or DEDA, a PLA2 inhibitor. Heparin, an IP3 receptor inhibitor, inhibited contraction whereas chelerythrine, a PKC inhibitor, had no effect. We conclude that histamine-induced contraction in cat duodenal smooth muscle cells is mediated by H1 receptors coupled to a PTX-insensitive Gq protein and results in activation of phosphatidylinositol-specific phospholipase C (PI-PLC).     

The Signaling Mechanism of Contraction Induced by ATP and UTP in Feline Esophageal Smooth Muscle Cells

P2 receptors are membrane-bound receptors for extracellular nucleotides such as ATP and UTP. P2 receptors have been classified as ligand-gated ion channels or P2X receptors and G protein-coupled P2Y receptors. Recently, purinergic signaling has begun to attract attention as a potential therapeutic target for a variety of diseases especially associated with gastroenterology. This study determined the ATP and UTP-induced receptor signaling mechanism in feline esophageal contraction. Contraction of dispersed feline esophageal smooth muscle cells was measured by scanning micrometry. Phosphorylation of MLC₂₀ was determined by western blot analysis. ATP and UTP elicited maximum esophageal contraction at 30 s and 10 μM concentration. Contraction of dispersed cells treated with 10 μM ATP was inhibited by nifedipine. However, contraction induced by 0.1 μM ATP, 0.1 μM UTP and 10 μM UTP was decreased by {"type":"entrez-nucleotide","attrs":{"text":"U73122","term_id":"4098075","term_text":"U73122"}}U73122, chelerythrine, ML-9, PTX and GDPβS. Contraction induced by 0.1 μM ATP and UTP was inhibited by Gαi₃ or Gαq antibodies and by PLCβ₁ or PLCβ₃ antibodies. Phosphorylated MLC₂₀ was increased by ATP and UTP treatment. In conclusion, esophageal contraction induced by ATP and UTP was preferentially mediated by P2Y receptors coupled to Gαi₃ and G q proteins, which activate PLCβ₁ and PLCβ₃. Subsequently, increased intracellular Ca²⁺ and activated PKC triggered stimulation of MLC kinase and inhibition of MLC phosphatase. Finally, increased pMLC₂₀ generated esophageal contraction.     

Importance of phosphoenolpyruvate carboxylase of Corynebacterium glutamicum during the temperature triggered glutamic acid fermentation

To give clues about the respective importance of phosphoenol-pyruvate carboxylase (PEPc) and pyruvate carboxylase (Pc) in Corynebacterium glutamicum metabolism during a temperature triggered glutamic acid fermentation, PEPc activity was genetically amplified and Pc activity was suppressed by biotin limitation in the culture medium. In absence of Pc activity, glutamate production was dramatically reduced whereas lactate excretion was strongly increased. Whereas PEPc amplification in excess of biotin (4 mg/L) only slightly modified the cell kinetics, under biotin limiting conditions this amplification strongly improved the glutamate production (4 microg/L). When Pc was absent, PEPc activity was sufficient to allow up to 70% of the maximal glutamate production rate and seemed to have an important anaplerotic role, especially at the beginning of the production phase. In contrast, Pc was predominant during the remainder of the glutamate fermentation.     

Anti-fertilization activity of a spirocyclic sesquiterpene isocyanide isolated from the marine sponge Geodia exigua and related compounds

(-)-10-epi-Axisonitrile-3, a spirocyclic sesquiterpene isocyanide obtained from the marine sponge Geodia exigua, immobilized sperm of sea urchin and starfish to block fertilization at the minimum effective concentration of 0.4 microg/ml. On the other hand, fertilized eggs developed normally to the gastrula stage in the presence of a 250-times higher concentration of the isocyanide. Analysis by (31)P NMR revealed an accumulation of phosphocreatine and a depletion of inorganic phosphate in the isocyanide-treated sperm, suggesting that (-)-10-epi-axisonitrile-3 inhibited the phosphocreatine shuttle participating in the high-energy phosphate metabolism, thereby immobilizing sperm to block fertilization. No analogs of (-)-10-epi-axisonitrile-3 containing different functionalities or isocyanides with different carbon skeleton exhibited such activity.     

The role of phosphatidylcholine and deoxycholic acid in inflammation

Aims

Phosphatidylcholine with deoxycholic acid (PC/DA) is widely used to reduce localized fat deposits with mild adverse effects. We previously demonstrated that PC induces lipolysis with mild PMN infiltration, while DA induces adipose tissue damage. Therefore, the aim of this study was to extend our understanding of the pro-inflammatory responses of PC, DA, and PC/DA.

Main methods

We evaluated the level of edema and polymononuclear (PMN) infiltration by histopathological examination. Myeloperoxidase (MPO) activity was analyzed using an MPO activity assay kit. Levels of inflammatory cytokines (IL-1β and IL-6) and PGE2 were measured by ELISA.

Key findings

A low and high dose of PC failed to induce an inflammatory response, whereas DA led to an intense inflammatory response in a dose dependent manner. Combined PC/DA treatment resulted in a mild inflammatory response that was notably less severe than higher DA. Together, these results demonstrated that DA plays a role in inflammation caused by combined PC/DA. Histopathological examination and measurement of MPO activity indicated that DA was the primary cause of edema and PMN infiltration. Further, increased levels of cytokines (IL-1β and IL-6) and PGE2 demonstrated that DA might directly induce inflammation, whereas PC alone has no effect on inflammation.

Significance

These results indicate that DA rather than PC is responsible for inflammation, and that PC may not aggravate inflammatory responses induced by DA. Thus, the results of this study suggest that the adverse effects of PC/DA during localized fat treatment may be solely due to DA.     

Genetic diversity and structure of the tropical seagrass Cymodocea serrulata spanning its central diversity hotspot and range edge

Aquatic Ecology - Persistence of populations at their distributional ranges relies on local population dynamics and the fitness of species with low dispersal potential. We analyzed the population...