Social group composition modulates the role of last male sperm precedence in post-copulatory sexual selection

In many species, the order in which males mate with a female explains much of the variation in paternity arising from post-copulatory sexual selection. Research in Drosophila suggests that mating order may account for the majority of the variance in male reproductive success. However, the effects of mating order on paternity bias might not be static but could potentially vary with social or environmental factors. To test this idea, we used an existing dataset, collated from an experiment we previously published (Morimoto et al., PLoS One, 11, 2016, e0154468), with the addition of unpublished data from the same experiment. These previous experiments manipulated larval density in Drosophila melanogaster which generated variation in male and female body size, assembled groups of individuals of different sizes, and measured the mating success and paternity share of focal males. The data presented here provides information on each focal male's mating order and the frequency in which focal males remated with same females (‘repetitive matings’). We combined this information with our previously reported focal male reproductive success to partition variance in paternity into male mating order and repetitive matings across groups that differed in the body size composition of males and females. We found, as expected, that male mating order explained a considerable portion of the variance in male paternity. However, we also found that the impact of male mating order on male paternity was influenced by the body size composition of groups. Specifically, males that tended to mate last had a greater paternity advantage, and displayed lower variance, in groups containing a heterogenous mixture male body sizes than in groups with a single male body size. Repetitive mating only had a minor contribution to the variance in male paternity share across all experiments. Overall, our findings contribute to the growing body of research showing that post-copulatory sexual selection is subject to socio-ecological influences.     

Randomised controlled trial of oxytocin alone versus oxytocin and ergometrine in active management of third stage of labour.

OBJECTIVE--To compare intramuscular oxytocin alone and intramuscular oxytocin with ergometrine (Syntometrine) for their effect in reducing the risk of postpartum haemorrhage when both are used as part of the active management of the third stage of labour. DESIGN--Double blind, randomised controlled trial. SETTING--Two metropolitan teaching hospitals in Perth, Western Australia. SUBJECTS--All women who expected a vaginal birth during the period of the trial. Informed consent was obtained. MAIN OUTCOME MEASURES--Postpartum haemorrhage, nausea, vomiting, and increased blood pressure. RESULTS--3497 women were randomly allocated to receive oxytocin-ergometrine (n = 1730) or oxytocin (n = 1753). Rates of postpartum haemorrhage (> or = 500 ml or > or = 1000 ml) were similar in both arms (odds ratio 0.90 (0.82); 95% confidence interval 0.75 to 1.07 (0.59 to 1.14) at 500 ml (1000 ml) threshold). The use of oxytocin-ergometrine was associated with nausea, vomiting, and increased blood pressure. CONCLUSIONS--There are few advantages but several disadvantages for the routine use of oxytoxinergometrine when prophylactic active management of the third stage of labour is practised. Further investigation of dose-response for oxytocin may be warranted.     

Arabidopsis carotenoid mutants demonstrate that lutein is not essential for photosynthesis in higher plants.

Lutein, a dihydroxy beta, epsilon-carotenoid, is the predominant carotenoid in photosynthetic plant tissue and plays a critical role in light-harvesting complex assembly and function. To further understand lutein synthesis and function, we isolated four lutein-deficient mutants of Arabidopsis that define two loci, lut1 and lut2 (for lutein deficient). These loci are required for lutein biosynthesis but not for the biosynthesis of beta, beta-carotenoids. The lut1 mutations are recessive, accumulate high levels of zeinoxanthin, which is the immediate precursor of lutein, and define lut1 as a disruption in epsilon ring hydroxylation. The lut2 mutations are semidominant, and their biochemical phenotype is consistent with a disruption of epsilon ring cyclization. The lut2 locus cosegregates with the recently isolated epsilon cyclase gene, thus, providing additional evidence that the lut2 alleles are mutations in the epsilon cyclase gene. It appears likely that the epsilon cyclase is a key step in regulating lutein levels and the ratio of lutein to beta,beta-carotenoids. Surprisingly, despite the absence of lutein, neither the lut1 nor lut2 mutation causes a visible deleterious phenotype or altered chlorophyll content, but both mutants have significantly higher levels of beta, beta-carotenoids. In particular, there is a stable increase in the xanthophyll cycle pigments (violaxanthin, antheraxanthin, and zeaxanthin) in both lut1 and lut2 mutants as well as an increase in zeinoxanthin in lut1 and beta-carotene in lut2. The accumulation of specific carotenoids is discussed as it pertains to the regulation of carotenoid biosynthesis and incorporation into the photosynthetic apparatus. Presumably, particular beta, beta-carotenoids are able to compensate functionally and structurally for lutein in the photosystems of Arabidopsis.     

The cellular pathway of sucrose transport in developing cotyledons ofVicia faba L. andPhaseolus vulgaris L.: a physiological assessment

The cellular pathway of sugar uptake in developing cotyledons of Vicia faba L. and Phaseolus vulgaris L. seed was evaluated using a physiological approach. The cotyledon interface with the seed coat is characterised by a specialised dermal cell complex. In the case of Vicia faba cotyledons, the epidermal component of the dermal cell complex is composed of transfer cells. Sucrose is the major sugar presented to the outer surface of both cotyledons and it is taken up from the apoplasm unaltered. Estimated sucrose concentrations within the apparent free space of Vicia and Phaseolus cotyledons were 105 and 113 mM respectively. Rates of in-vitro uptake of [¹⁴C]sucrose by cotyledon segments or by whole cotyledons following physical removal or porter inactivation of the outer cells demonstrated that, for both Vicia and Phaseolus cotyledons, the dermal cell complexes are the most intense sites of sucrose uptake. Accumulation of [¹⁴C]sucrose in the storage parenchyma of whole cotyledons was directly affected by experimental manipulation of uptake by the outer cell layers and plasmolytic disruption of the interconnecting plasmodesmata. These findings indicated that sucrose accumulated by the dermal cell complexes is transported symplasmically to the storage parenchyma. Overall, it is concluded that the dermal cell complexes of the developing legume embryo, irrespective of the presence or absence of wall ingrowths, are the major sites for the uptake of sucrose released from the maternal tissues to the seed apoplasm. Thereafter, the accumulated sucrose is transported radially inward through the symplast to the storage parenchyma.Abbreviations AFS apparent free space - CF 5-(6)-carboxyfluorescein - CFDA 5-(6)-carboxyfluorescein diacetate - Mes 2-(N-morpholino)ethanesulfonic acid - PCMBS p-chloromercuribenzenesulfonic acid - SRG sulphorhodamine G The investigation was supported by funds from the Research Management Committee, The University of Newcastle and the Australian Research Council. One of us, R. McDonald, gratefully acknowledges the support of an Australian Postgraduate Research Award. We are grateful to Stella Savoury for preparing the photomicrographs.     

Sperm motility in the presence of boundaries

The fluid dynamics of sperm motility near both rigid and elastic walls is studied using the immersed boundary method. Simulations of both single and interacting organisms are presented. In particular, we find that nearby organisms originally undulating with a 90° phase shift may adjust their relative swimming velocities and phase-lock. Comparisons with previous analytical results are also discussed. The tendency of a near-wall to attract organisms is demonstrated.     

Tyrosine phosphorylation of phosphatase inhibitor 2

Inhibitor 2 is a heat-stable protein that complexes with the catalytic subunit of type-1 protein phosphatase. The reversible phosphorylation of Thr 72 of the inhibitor in this complex has been shown to regulate phosphatase activity. Here we show that inhibitor 2 can also be phosphorylated on tyrosine residues. Inhibitor 2 was ³²P-labeled by the insulin receptor kinase in vitro, in the presence of polylysine. Phosphorylation of inhibitor 2 was accompanied by decreased electrophoretic mobility. Dephosphorylation of inhibitor 2 by tyrosine phosphatase 1B, restored normal electrophoretic mobility. Phosphotyrosine in inhibitor 2 was detected by immunoblotting with antiphosphotyrosine antibodies and phosphoamino acid analysis. In addition, following tryptic digestion, one predominant phosphopeptide was recovered at the anode. The ability of inhibitor 2 to inhibit type-1 phosphatase activity was diminished with increasing phosphorylation up to a stoichiometry of 1 mole phosphate incorporated/mole of inhibitor 2, where inhibitory activity was completely lost. These data demonstrate that inhibitor 2 can be phosphorylated on tyrosine residues by the insulin receptor kinase, resulting in a molecule with decreased ability to inhibit type-1 phosphatase activity.     

Influence of carbon and nitrogen sources on glutathione catabolic enzymes inCandida albicans during dimorphism

The effect of carbon sources, glucose and sucrose, and nitrogen sources such as ammonia, glutamate andl-citrulline on the activities of glutathione metabolic enzymes has been studied. Yeast and mycelial cells were used to identify changes in activity levels of glutathione reductase (GSSGR), glutathione transferase (GST), glutathione peroxidase (GPX) and -glutamyl transpeptidase (GGT). Enzyme activities from cells grown in sucrose media were lower than in glucose media regardless of the enzyme tested, morphological form, or the growth interval. In all enzymes except GST, activity was higher in yeast form than in mycelia, regardless of nitrogen source, with lower activity from 24 to 72 h than at 96 h. In citrulline media, yeast form showed the maximum GST, GGT, and GPX activity. In ammonia-amended media, mycelia showed maximum activity in GGT, whereas in glutamate media, mycelia showed the maximum activity in GST. Also, the type of nitrogen source had no effect on GPX activity in the mycelial form. Finally, changing the nitrogen source showed no significant effect on GSSGR activity, either in the yeast or mycelial form.     

Intraspecific variation of spectral sensitivity in threespine stickleback (Gasterosteus aculeatus) from different photic regimes

To examine the influence of the spectral characteristics of underwater light on spectral sensitivity of the ON and OFF visual pathways, compound action potential recordings were made from retinal ganglion cells of threespine stickleback from different photic regimes. In fish from a red-shifted photic regime (P₅₀ 680 nm for downwelling light at 1m), peak sensitivity of both the ON and OFF pathways was limited to long wavelength light (_max 600–620). In contrast, the ON pathway of fish from a comparatively blue-shifted (P₅₀ 566 nm) photic regime exhibited sensitivity to medium (_max 540–560) and long (_max 600 nm) wavelengths, while the OFF pathway exhibited peak sensitivity to only medium (_max 540 nm) wavelength light. In a third population, where the the ambient light is moderately red-shifted (P₅₀ 629 nm), the ON pathway once again exhibited only a long wavelength sensitivity peak at 620 nm, while the OFF pathway exhibited sensitivity to both medium (_max 560 nm) and long (_max 600–620 nm) wavelength light. These findings suggest that the photic environment plays an integral role in shaping spectral sensitivity of the ON and OFF pathways.     

Endotoxin shock: prevented by naloxone in intact but not hypophysectomized rats

Previous studies established that naloxone reverses hypotension in endotoxin, hemorrhagic, and spinal shock. We studied endotoxin shock in hypophysectomized (Hx) rats, which have little circulating beta-endorphin. Hx or intact rats received surgically implanted jugular catheters for drug injection and aortic catheters for arterial blood pressure (MAP) recording. On the second day after implantation, rats were pretreated with either naloxone or saline. Two minutes later each rat received endotoxin. Following endotoxin, all rats showed a brief biphasic hypertensive-hypotensive response followed by stabilization of MAP near baseline. Within 20 min, all Hx rats, regardless of pretreatment, and the saline-treated intact rats, showed progressive hypotension (P less than 0.005). Only the naloxone-pretreated intact rats maintained a stable MAP. Plasma endorphin measured at 20 min was undetectable in Hx rats in contrast to intact rats (P less than 0.001); plasma corticosterone levels were likewise suppressed in the Hx rats (P less than 0.01). Thus (1) naloxone protected only the rats with an intact pituitary-adrenal-sympathetic system, and (2) pituitary endorphin is not required to generate endotoxin shock in hypophysectomized rats.     

Prostaglandin-mediated hyperemia and renin-mediated hypertension during acute ureteral obstruction

Acute elevation of ureteral pressure to 100 mm Hg in anesthetized dogs (n=7) resulted in an increase (P<0.005) in systemic blood pressure from 151±7 to 163 ± 7 mm Hg, a transient (15 min) increase (P<0.05) in renal blood flow from 413 ± 27 to 465 ± 27 ml/min C and a rise (P<0.05) in plasma renin activity from 6.0 ± 1.6 to 10.3 ± 2.1 ng/ml/hr. Pretreatment with a competitive inhibitor of angiotensin II, i.e. sar¹gly⁸AII, abolished the hypertensive response to acute ureteral obstruction, and pretreatment with 2 mg/kg of either indomethacin (n=6) or meclofenamate (n=3), 15 min before obstruction, prevented the hyperemic response. These results suggest that acute ureteral obstruction leads to hypertension via activation of the renin-angiotensin system and hyperemia via a prostaglandin-initiated mechanism.