Egg presence, egg loss, and female mate preferences in the sand goby (Pomatoschistus minutus)

We studied the effect of egg presence on female mate choicein a fish with paternal care. Females who were allowed a freechoice between two males mated within a shorter time than femaleswho were randomly assigned to a particular male. When a secondfemale was allowed to choose among the males, she preferredthe same male as the previous female. This result shows thatfemales are concordant in their mate choice. When the initialfemale was randomly assigned to mate with one of two males (forcedchoice), the second female mated randomly with respect to thefirst one. Thus females do not prefer males with eggs. If theinitial female was given a free choice, but the eggs were removedfrom the chosen male, the test female mated randomly. When boththe males initially had mated but one randomly determined male'seggs were removed, the test female preferred the male who wasstill guarding eggs. These experiments show that females avoidspawning in unsuccessful nests. When the females in the freechoice/egg removal experiment mated with the unsuccessful malethere was a considerably bigger size difference in favor ofthis male than when the females mated with the other male. Weconclude that female sand gobies show clear mate preferences,but that they do not prefer males with eggs over males withouteggs. They do, however, avoid mating with males guarding unsuccessfulnests. We therefore suggest that egg loss could be an importantfactor selecting for egg preference.     

Degradation of acetylcholine receptor in diaphragms of rats with experimental autoimmune myasthenia gravis.

The degradation of acetylcholine receptor observed in denervated and innervated normal rat diaphragms in organ culture is stimulated by exogenous antireceptor serum. In this paper we demonstrate that diaphragms from rats with experimental autoimmune myasthenia gravis contain reduced amounts of acetylcholine receptor. Acetylcholine receptor from myasthenic, but not from normal, rats has antibody bound to it and is degraded at an accelerated rate. We conclude that in the chronic phase of experimental autoimmune myasthenia gravis increased acetylcholine receptor degradation can be accounted for by a mechanism involving antigenic modulation, and that such a process can contribute to the clinical symptoms of impaired neuromuscular transmission.     

Effect of major surgery on the release of interferon gamma by peripheral blood mononuclear cells: an investigation at the single cell level using the reverse haemolytic plaque assay.

The release of interferon gamma (IFN-gamma) by peripheral blood mononuclear cells from patients undergoing abdominal aortic aneurysm repair was measured using the reverse haemolytic plaque assay. The plasma of these patients was also assayed for interferon gamma using enzyme-linked immunosorbent assay (ELISA). Peripheral blood mononuclear cells from the surgical patients released significantly more IFN-gamma by 9 hours after incision than that released prior to surgery (P less than 0.001). This change persisted up to 9 days after surgery. Plasma IFN-gamma was not detectable using either of two different ELISA techniques. The increased secretion of IFN-gamma by peripheral blood mononuclear cells following major surgery may be a beneficial component of the host's immune response to injury.     

Functional equivalence of monomeric and dimeric forms of purified acetylcholine receptors from Torpedo californica in reconstituted lipid vesicles

Acetylcholine receptors from Torpedo californica electric organ were solubilized and purified under conditions which prevent inactivation of the agonist-regulated cation channels. The dimer form of the receptors was preserved during purification. Treatment with reducing agents converted dimers into monomers. Receptor monomers and dimers were separately reconstituted into soybean lipid vesicles by the cholate dialysis technique. Reconstituted monomers and dimers were functionally equivalent with respect to their carbamylcholine-induced dose-dependent uptake of 22Na+, the total flux of 22Na+ per receptor during the permeability response, and the occurrence of desensitization. Evidence against non-covalent association of monomers to produce dimeric functional units was obtained using glutaraldehyde as a crosslinking agent. These results show that both the acetylcholine-binding sites and the agonist-regulated cation-specific channel are contained within the alpha 2 beta gamma delta subunit structure of the acetylcholine receptor monomer.     

Dispersal, edaphic fidelity and speciation in species-rich Western Australian shrublands: evaluating a neutral model of biodiversity

Over evolutionary time, the number of species in a community reflects the balance between the rate of speciation and the rate of extinction. Over shorter time‐scales local species richness is also affected by how often species move into and out of the local community. These processes are at the heart of Hubbell's ‘unified neutral theory of biodiversity’ ( Hubbell 2001 ). Hubbell's spatially implicit, dispersal‐limited neutral model is the most widely used of the many implementations of neutral theory and it provides an estimate of the rate of speciation in a metacommunity (if metacommunity size is known) and the rate at which species migrate into the local community from the wider metacommunity. Recently, this neutral model has been used to compare rates of speciation and migration in the species‐rich fynbos of South Africa and in neotropical forests. Here we use new analytical methods for estimating the neutral model's parameters to infer speciation and dispersal rates for three sites in species‐rich sclerophyll shrublands (equivalent to fynbos) in Western Australia (WA). Our estimates suggest that WA shrublands are intermediate between fynbos and tropical rainforest in terms of speciation and dispersal. Although a weak test, the model predicts species abundance distributions and species accumulation curves similar to those observed at the three sites. The neutral model's predictions also remain plausible when confronted with independent data describing: (1) known edaphic relationships between sites, (2) estimates of metacommunity species richness and (3) rates of speciation among resprouters and nonsprouters. Two of the site pairs, however, show species turnovers significantly different from those predicted by the spatially implicit form of the neutral model that we use. This suggests that non‐neutral processes, in this case probably edaphic specialisation, are important in the WA shrubland metacommunity. The neutral model predicts similar rates of speciation in resprouter and sprouter taxa, a finding supported by recent molecular phylogenies. Finally, when converted into temporally scaled speciation rates and species longevities, the estimates produced by the neutral model seem implausible. The apparent departure from neutrality in the turnover of species between some sites and the implausible temporal dynamics may be due to the particular model chosen and does not reduce the significance of our other results, which confirm that local dispersal limitation, coupled with broader scale edaphic fidelity, combine to structure this biodiverse metacommunity.     

Vaginal microbiome-hormonal contraceptive interactions associate with the mucosal proteome and HIV acquisition

Alterations to the mucosal environment of the female genital tract, such as genital inflammation, have been associated with increased HIV acquisition in women. As the microbiome and hormonal contraceptives can affect vaginal mucosal immunity, we hypothesized these components may interact in the context of HIV susceptibility. Using previously published microbiome data from 685 women in the CAPRISA-004 trial, we compared relative risk of HIV acquisition in this cohort who were using injectable depot medroxyprogesterone acetate (DMPA), norethisterone enanthate (NET-EN), and combined oral contraceptives (COC). In women who were Lactobacillus-dominant, HIV acquisition was 3-fold higher in women using DMPA relative to women using NET-EN or COC (OR: 3.27; 95% CI: 1.24–11.24, P = 0.0305). This was not observed in non-Lactobacillus-dominant women (OR: 0.95, 95% CI: 0.44–2.15, P = 0.895) (interaction P = 0.0686). Higher serum MPA levels associated with increased molecular pathways of inflammation in the vaginal mucosal fluid of Lactobacillus-dominant women, but no differences were seen in non-Lactobacillus dominant women. This study provides data suggesting an interaction between the microbiome, hormonal contraceptives, and HIV susceptibility.