Drosophila seminal sex peptide associates with rival as well as own sperm, providing SP function in polyandrous females

When females mate with more than one male, the males’ paternity share is affected by biases in sperm use. These competitive interactions occur while female and male molecules and cells work interdependently to optimize fertility, including modifying the female’s physiology through interactions with male seminal fluid proteins (SFPs). Some modifications persist, indirectly benefiting later males. Indeed, rival males tailor their ejaculates accordingly. Here, we show that SFPs from one male can directly benefit a rival’s sperm. We report that Sex Peptide (SP) that a female Drosophila receives from a male can bind sperm that she had stored from a previous male, and rescue the sperm utilization and fertility defects of an SP-deficient first-male. Other seminal proteins received in the first mating ‘primed’ the sperm (or the female) for this binding. Thus, SP from one male can directly benefit another, making SP a key molecule in inter-ejaculate interaction.

Optimalisasi Pembekuan Sperma Limbah Kauda Epididimis Kambing Lokal dengan Metode Bertahap dan Stabilisasi

Buck slaugthering produce waste such as testicles including epididymis which contain fertile sperm. Utilization of cauda epididymis as the sources of sperm for producing goat frozen sperm was not reported yet. The aims of this study were improving the frozen-thawed sperm using stabilization and multistep methods which recovered from the waste of buck slaughtering as the source of sperma. Cauda epididymis spermatozoa which was washed then diluted using extender 1 (Tris-citrate-antibiotics) and extender 2 (extender 1- glycerol-egg yolk). The extender 2 addition was performed by single or multistep methods then freezed. Modification in the pre freezing proces were performed by comparing the conventional equilibration and stabilization methods. The sperm suspension was incubated in 4°C for 2 hours after filling-sealing into straws on the equilibration group whether the stabilization group was cooled in tube 15 mL. All cooled straws from both groups were placed 4 cm horizontally on liquid nitrogen surface for 10 minutes and then plunged into liquid nitrogen for storage. The evaluation of motility parameters such as pattern of the movement and motility percentation were done followed the standard methodology. The student t-test, correlation and one-way ANOVA were used for data analysis with P<0.05. The results showed that multistep dilution method could increase the motility (25.0 ± 1.8 %) compared with single step (18.3 ± 1.7 %). Pre freezing method with stabilization also resulted higher motility (24.2 ± 2.0 %) than equilibration method (17.5 ± 2.8 %). The pattern of the movement were not different between all methods and its combination. The multistep dilution method and stabilization cooling method as well as its combination seems could increase the quality of frozen-thawed cauda epididymis spermatpzoa of local buck.

How multiple mating by females affects sexual selection

Multiple mating by females is widely thought to encourage post-mating sexual selection and enhance female fitness. We show that whether polyandrous mating has these effects depends on two conditions. Condition 1 is the pattern of sperm utilization by females; specifically, whether, among females, male mating number, m (i.e. the number of times a male mates with one or more females) covaries with male offspring number, o . Polyandrous mating enhances sexual selection only when males who are successful at multiple mating also sire most or all of each of their mates' offspring, i.e. only when Cov ♂ ( m , o ), is positive. Condition 2 is the pattern of female reproductive life-history; specifically, whether female mating number, m , covaries with female offspring number, o . Only semelparity does not erode sexual selection, whereas iteroparity (i.e. when Cov ♀ ( m , o ), is positive) always increases the variance in offspring numbers among females, which always decreases the intensity of sexual selection on males. To document the covariance between mating number and offspring number for each sex, it is necessary to assign progeny to all parents, as well as identify mating and non-mating individuals. To document significant fitness gains by females through iteroparity, it is necessary to determine the relative magnitudes of male as well as female contributions to the total variance in relative fitness. We show how such data can be collected, how often they are collected, and we explain the circumstances in which selection favouring multiple mating by females can be strong or weak.