Multiple paternity in the red-eyed treefrog Agalychnis callidryas (Cope)

DNA fingerprinting of tadpoles from two different ‘one female-two male’ matings of the red-eyed treefrog, Agalychnis callidryas, revealed multiple paternity of offspring. Offspring were assigned paternity based on bands shared with the putative father, but not shared between putative fathers or with the mother. Paternity was split 44/56% and 36/64% in two matings. These results do not support a hypothesis of sperm priority in access to unfertilized eggs by primary males. Multiple paternity may be commonplace in species of anurans with matings by multiple males.     

The transport of morphologically abnormal sperm in the female reproductive tract of mice

Mice of the PL/J strain exhibit a high percentage of morphologically abnormal sperm and provide a model for studying the function of abnormal sperm. The ability of such sperm to reach the site of fertilization within the female reproductive tract has been investigated. We have found a decrease in the percentage of structurally abnormal sperm within the population that reaches the oviduct. This observation suggests either that there is an active selection against abnormal sperm or that they are physiologically disadvantaged in reaching the site of fertilization.     

A phosphorus NMR study of the reaction products of cis-diamminedichloroplatinum (II) with a double-helical oligonucleotide and with DNA

The structural distortion of oligonucleotides upon cis-PtCl2(NH3)2[d(T-C-T-C-G-G-T-C-T-C)-N7(5), N7(6)] reveals shifting of 4 phosphorus resonances due to platination. 3 Resonances could be assigned by selective 31P-irradiation, showing P(6) (P between the two Gs) to be shifted 1.5 ppm to low field. In the concomitant double strands P(6) is shifted 0.9 ppm to lower field. A similar peak has been observed in platinated salmon sperm DNA (37 degrees C), indicating that Pt-binding to GpG-fragments in DNA is similar to that found for the decanucleotide, so the distortion of DNA might be comparable.     

Isolation of a high molecular weight glycoconjugate derived from the surface of S purpuratus eggs that is implicated in sperm adhesion

Sea urchin sperm–egg adhesion is mediated by bindin, a sperm surface protein that has lectin-like activity. Bindin agglutinates eggs, and this interaction has been shown to be inhibited by glycopeptides released from the egg surface by protease treatment. In this study, we report the purification and properties of such an egg surface glycoconjugate that may be involved in sperm adhesion. The glycoconjugate was partially purified by gel filtration and affinity chromatography on bindin particles. Upon gel filtration on Sepharose CL 4-B, the glycoconjugate elutes near the void volume, suggesting that it has a molecular weight in excess of one million. In addition, we have found that the egg surface glycoconjugate agglutinates bindin particles, indicating that it is multivalent. Carbohydrate analysis indicates that the glycoconjugate is composed primarily of fucosc, xylose, galactose, and glucose. This purified egg surface component is the most potent inhibitor of bindin-mediated egg agglutination yet described.     

Effect of the presence and location of corpus luteum on competence of bovine cumulus-oocyte complexes

This study aimed to determine the effect of presence of the corpus luteum (CL) and its influence on cumulus–oocyte complexes (COCs) obtained from the ipsilateral or contralateral ovary in bovine on the recovery and capacity of the oocytes to sustain mono-spermic fertilization, undergo preimplantation development, and develop to the blastocyst stage. Ovaries were collected at a local slaughterhouse and kept in pairs corresponding to the same animal. In the first experiment the variables evaluated were compared between cows with (CCL⁺) and without (CCL^-) CL, and for the second experiment, comparisons were made between ovaries with an ipsilateral (CL⁺), contralateral (CL⁻), and no (NCL). The recovery rate of COCs was higher in ovaries from CCL⁻ cows, and a higher proportion of grade 1 COCs were recovered from this group. A higher proportion of metaphase I oocytes at 7 h of maturation, and a higher rate of cleavage were observed in the CCL⁺ group; however, a higher proportion of embryos were obtained from the CCL⁻ group. Besides, COCs from the CL⁺ group had a lower proportion of grades 1 and 2 morphological qualities, lower rate of metaphase II oocytes at 22 h of maturation, and lower rate of formation of two pronuclei, whereas a higher proportion of unfertilized oocytes after in vitro fertilization. On the other hand, the COCs from the CL⁻ group displayed a lower proportion of oocytes with more than two pronuclei, higher cleavage rate, and higher final blastocyst production were obtained when compared to CL+. Thus, the effects of CL on the competence of bovine COCs are different depending on the anatomical proximity of their location in the animal, negatively affecting the quality of COCs located in the same ovary, but not having negative effects on the competence of COCs in the ovaries contralateral to their location.     

High frequency of polyandry in a lek mating system

The adaptive significance of polyandry by female birds in theabsence of direct benefits remains unclear. We determined thefrequencies of polyandrous mating and multiple paternity inthe ruff, a lekking shorebird with a genetic dimorphism inmale mating behavior. More than half of female ruffs mate with, and have clutches fertilized by, more than one male. Individualfemales mate with males of both behavioral morphs more oftenthan expected. Polyandrous mating was more likely followingcopulation interference, but interference was uncommon. Themultiple paternity rate of ruffs is the highest known for avian lekking species and for shorebirds. The general hypothesis thatpair-bond constraints are the major selective factor favoringmultiple mating in birds does not predict our findings. Activegenetic diversification, which has been widely dismissed asa functional explanation for polyandrous mating in birds, mayapply with respect to the behavioral polymorphism in ruffs becauseof a Mendelian genetic basis for male behavioral morph determinationand aspects of male—male cooperation and female choice.However, rates of multiple paternity in other species of lekkingbirds are higher than generally realized, and the potentialbenefits of diversification in general deserve further consideration.     

Sperm quality, secondary sexual characters and parasitism in roach (Rutilus rutilus L.)

According to sperm competition models, a male spawning in a disfavoured role should have spermatozoa with higher velocity but shorter longevity compared with a male spawning in a favoured role. Moreover, immunosuppressive androgens are needed to produce both secondary sexual characters and sperm cells. The 'sperm protection' hypothesis suggests that the immunosuppressive action of androgens has evolved to protect haploid spermatozoa, which are antigenic, from autoimmune attacks. Therefore, a male with high sexual ornamentation may be more susceptible to diseases but may possess better quality ejaculate than his less ornamented rival. We studied sexual ornamentation (breeding tubercles), ejaculation quality (sperm concentration, longevity and spermatozoal velocity) and intensity of parasitism in the cyprinid, Rutilus rutilus . Sperm longevity and spermatozoal velocity were positively correlated. Males having elaborated sexual ornamentation had longer-lived sperm and more Myxobolus mülleri parasites in the liver compared with males with low ornamentation. However, no difference was found between males with different degrees of ornamentation with respect to sperm concentration, spermatozoal velocity or other parasites. Since the highly ornamented males had higher sperm longevity, the present results are partly consistent with the predictions of the sperm competition models and the 'sperm protection' hypothesis.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 111–117.     

Determinants of sperm transfer in the scorpionfly Panorpa cognate: male variation, female condition and copulation duration

Recent studies suggest that sperm production and transfer may have significant costs to males. Male sperm investment into a current copulation may therefore influence resources available for future matings, which selects for male strategic mating investment. In addition, females may also benefit from actively or passively altering the number of sperm transferred by males. In the scorpionfly Panorpa cognata, the number of sperm transferred during copulation depended on copulation duration and males in good condition (residual weight) copulated longer and also transferred more sperm. Moreover, sperm transferred and stored per unit time was higher in copulations with females in good condition than in copulations with females in poor condition. Males varied greatly and consistently in their sperm transfer rate, indicative of costs associated with this trait. The duration of the pairing prelude also varied between males and correlated negatively with the male's sperm transfer rate, but no other male character correlated significantly with male sperm transfer rate. The results are consistent with strategic mating effort but sperm transfer could also be facilitated by the physical size of females and/or females in good condition may be more cooperative during sperm transfer.     

Homogeneity of recombination rate within a conserved region on BTA3 that contains QTL

The D3S20-D3S34-D3S3 region on BTA3 contains quantitative trait loci (QTL) controlling milk production traits. This region also displays extensive conservation of synteny among several species including cattle, humans, mice and sheep. In this study, we evaluated the adjacent intervals D3S20-D3S34 and D3S34-D3S3 for differences in recombination rate (theta) among bulls in order to assess the suitability of population-based estimates of theta for marker assisted selection and to explore the relationship between variation in theta and chromosome breakpoints associated with mammalian evolution. Using sperm typing, thetaD3S20-D3S34 and theta D3S34-D3S3 were estimated for six triply heterozygous bulls. Recombination frequency ranged from 6.2 to 12.5% and from 9.7 to 19.2% for the D3S20-D3S34 and D3S34-D3S3 intervals, respectively. However, significant variation in theta was not detected between bulls for either interval (D3S20-D3S34 chi(2)5 d.f.=2.59, P < 0.90; D3S34-D3S3 chi(2)5 d.f.=3.72, P < 0.75). The observed differences in theta were most readily attributed to differences in allele-specific amplification efficiencies among bulls. Our results suggest that the positions of QTL in this region can be reliably determined from population data and therefore accurate marker-assisted selection can be performed for desirable alleles without concern for variation in theta. Furthermore, when considered with results of earlier studies, these findings support a correlation between the existence of evolutionary breakpoints or chromosome rearrangements and variation in theta.