Is the hook of muroid rodent's sperm related to sperm train formation?

Competition between spermatozoa of rival males to gain fertilizations has led to a wide array of modifications in sperm structure and function. Sperm cells of most muroid rodents have hook‐shaped extensions in the apical–ventral tip of the head, but the function of this structure is largely unknown. These ‘hooks’ may facilitate aggregation of spermatozoa in so‐called ‘trains’, as an adaptation to sperm competition, because sperm in trains may swim faster than free‐swimming cells. However, there is controversy regarding the role of the hook in train formation, and in relation to whether it is selected by sperm competition. We examined spermatozoa from muroid rodents with varying levels of sperm competition to assess whether (i) sperm aggregates are common in these taxa, (ii) presence of a hook relates to the formation of sperm aggregations, and (iii) formation of sperm aggregations is explained by sperm competition. Our analyses in 25 muroid species revealed that > 92% of spermatozoa swim individually in all species, with the exception of the wood mouse, Apodemus sylvaticus, which has ~50% spermatozoa swimming freely. Species with hooked spermatozoa had higher sperm competition levels and longer sperm than species whose sperm lack a hook. Neither the presence of hook nor sperm competition levels were related to the percentage of sperm in aggregations. Thus, (i) sperm aggregates in muroid rodents are an exceptional trait found only in a few species, (ii) evolution of the sperm hook is associated to sperm competition levels, but (iii) the hook is unlikely to be related to the formation of sperm aggregates. The evolutionary significance of the sperm head hook thus remains elusive, and future studies should examine potential roles of this pervasive structure in sperm's hydrodynamic efficiency and sperm–female tract interactions.     

When do sperm of the sea urchin,Pseudocentrotus depressus,undergo the acrosome reaction at fertilization?

Jelly coats of the sea urchin, Pseudocentrotus depressus, were stripped off the eggs, and the eggs were “inseminated.” After penetration through the isolated jelly hull, sperm swarmed in the cavity previously occupied by the egg. Electron microscopic examination could not detect any sperm with reacted acrosome. Observation was also made of the sperm penetrating through the intact jelly coat-egg complex. Although a number of sperm were examined in ultrathin sections, only those attached to the vitelline layer had undergone the acrosome reaction; those sperm embedded in jelly but not attached to the vitelline layer had not undergone the acrosome reaction. The sequence of events in fertilization of this species and of other echinoids is discussed.     

The physiological acquisition of amoeboid motility in nematode sperm: Is the tail the only thing the sperm lost?

Nematode spermatozoa are highly specialized amoeboid cells that must acquire motility through the extension of a single pseudopod. Despite morphological and molecular differences with flagellated spermatozoa (including a non‐actin‐based cytoskeleton), nematode sperm must also respond to cues present in the female reproductive tract that render them motile, thereby allowing them to locate and fertilize the egg. The factors that trigger pseudopod extension in vivo are unknown, although current models suggest the activation through proteases acting on the sperm surface resulting in a myriad of biochemical, physiological, and morphological changes. Compelling evidence shows that pseudopod extension is under the regulation of physiological events also observed in other eukaryotic cells (including flagellated sperm) that involve membrane rearrangements in response to extracellular cues that initiate various signal transduction pathways. An integrative approach to the study of nonflagellated spermatozoa will shed light on the identification of unique and conserved processes during fertilization among different taxa. Mol. Reprod. Dev. 77: 739–750, 2010. © 2010 Wiley‐Liss, Inc.     

GalNAcβ1,3-linked paragloboside carries the epitope of a sperm maturation-related glycoprotein that is recognized by the monoclonal antibody MC121

The functional maturation of spermatozoa during epididymal transit in mammals accompanies the changes in their plasma membrane due to the binding or removal of proteins or interactions with the proteases, glycosidases and glycosyltransferases present in the epididymis. In order to study the surface changes in spermatozoa during their maturation in the epididymis, we previously established several monoclonal antibodies against the 54 kDa sialoglycoprotein of mouse cauda epididymal spermatozoa, which gradually increased the expression of antigenic determinants during epididymal transit. One of these monoclonal antibodies, MC121, reacted with mouse sperm glycoproteins on a polyvinylidene fluoride membrane after desialylation of the glycoproteins, and the treatment of the desialylated sperm glycoproteins with β-N-acetylhexosaminidase greatly decreased the expression of the antigenic determinants. In addition to reacting with mouse cauda epididymal spermatozoa, MC121 reacted with human red blood cells (hRBCs). MC121 induced agglutination of sialidase-treated hRBCs and stained hRBCs fixed with formalin vapor much more heavily than it stained hRBCs fixed with methanol. The thin layer chromatography (TLC) immunostaining of the sialidase-treated lipids of hRBCs with MC121 suggested that the epitope-bearing molecule is a glycosphingolipids (GSL), and that MC121 reacts with a pentaose-GSL. Analysis of sialidase-treated GSLs by TLC-Blot-Matrix Assisted Laser Desorption Ionization Time-of-Flight mass spectrometry (MALDI TOF MS) revealed that the GSL bound by MC121 was [HexNAc][HexNAc + Hex][Hex][Hex]-Cer. The lipid band stained with mAb TH2, which is specific for a GSL, GalNAcβ1-3Galβ1-4GlcNAcβ1-3Galβ1-4Glcβ1-ceramide. These results indicated that the epitope to which MC121 binds is present in a neolacto-series GSL, IV³GalNAcβ-nLc₄Cer² sequence.     

基于cas9/gRNA创制毛果杨PtrFLA31/34突变体

束状阿拉伯半乳聚糖蛋白（FLA）对植物生长发育都起着重要作用。基于生物信息学分析,我们识别毛果杨FLA家族有46个成员;进化分析显示毛果杨FLA家族分为A、B、C、D 4个亚族,且PtrFLA31和PtrFLA34处在进化树的一个小分支。半定量RT-PCR分析表明,PtrFLA31和PtrFLA34在毛果杨木质组织特异性、高水平表达。为了鉴定PtrFLA31和PtrFLA34在木材形成上的功能,我们用Cas9/gRNA技术敲除PtrFLA31/34,获得3株毛果杨fla31/34敲除双基因突变体材料。     

Inhibiting sperm motility for male contraception: will the sperm tail be its "Achilles heel"?

Blocking sperm motility has great appeal as a male contraceptive. A drug that targets sperm motility might have a very rapid onset of action, possibly allowing for administration immediately prior to intercourse and minimizing concerns about compliance. Promising sperm motility targets include transmembrane calcium channels, a unique adenylyl cyclase, and novel flagellar proteins. Future efforts directed towards effectively antagonizing the activities of these or other such targets will be required to completely impair sperm production, function, or both and create a usable male "pill."     

How is a giant sperm ejaculator formed? Development of the Zenker organ after the last moult in Pseudocandona marchica (Crustacea,Ostracoda, Candonidae)

‘Giant sperm’, in terms of exceptionally long spermatozoa, occur in various taxa in the animal kingdom, particularly in arthropods. In freshwater ostracods (Cypridoidea) reproducing with giant sperm, males are equipped with a pair of specialized ejaculators, or Zenker organs, located in the distal part of vas deferens.     

Is the sperm type of the Nemertodermatida close to that of the ancestral Platyhelminthes?

Results from a transmission electron microscope study of the spermiogenesis and spermatozoon of Meara stichopi (Nemertodermatida, Platyhelminthes) indicate that the sperm type of the Nemertodermatida has evolved from the primitive metazoan sperm type rather than from an aberrant biflagellar sperm type as found in many other flatworms. The spirally coiled mitochondrial derivative in the mature spermatozoon develops from two large oval mitochondria in the early spermatid stages. A single flagellum grows out from a peripheral basal body adjacent to a perpendicularly placed accessory centriole. The basal body moves to a distal depression of the nucleus, and becomes equipped with an anchoring fibre apparatus. Most of the flagellum becomes axially incorporated into the developing spermatid. No trace of a second flagellum was found in any stage of the spermiogenesis. Rounded vesicles appear around the proximal, tapering end of the elongating nucleus. Most probably these vesicles form a thin acrosomal structure in the mature spermatozoon. No dense bodies, characteristic of many other ‘turbellarian’ flatworm sperm types, were found. This revised version was published online in July 2006 with corrections to the Cover Date.     

What affects fertility of sexed bull semen more, low sperm dosage or the sorting process?

Until now it has been unclear to what extent the reduced fertility with sexed semen in the dairy industry is caused by too few sperm per AI dose, or by the effect of flow cytometric sorting, which is the established procedure for sexing semen. Therefore, we evaluated the effects of low sperm numbers per dose with and without sorting on non-return rates after 56 days (NRR56); in addition, we evaluated the effects of bulls, in order to further optimize use of sexed semen.Based on results of using sexed semen from seven Holstein bulls, an overall numerical decline of 13.6% in NRR56 was observed (P < 0.05). About two-thirds of this decline (8.6%) was due to the low dose (P < 0.05), and a third (5.0%) due to the process of sorting (P < 0.05). The effect of low dosage and sorting differed among bulls. We observed a sex ratio of 91.6% females for sexed semen from the first 131 calves born.Currently the best way to increase fertility of sexed semen is by closely monitoring fertility so that the highest fertility bulls are used, and by improving farm animal management. However, to make substantial progress, more in depth studies are needed on the sexing technology, especially on aspects such as sorting procedures and sperm dosage.     

Cloning of rat sp56,the homologue of mouse sperm ZP3 receptor—sp56

Mouse sp56 is considered as one of the candidates for mouse zona pellucida 3(mZP3)receptor,Up to date,its homologue has only been cloned from guinea pig,namely,AM67.Based on the cDNA sequence of mouse sp56,we designed a pair of primer to amplify its homologue from rat testis cDNA.Using RT-PCR, two tragments of 743 bp and 938 bp were amplified.The PCR products show very high homology to mouse sp56.However,the 743 bp product completely lacks one of the seven Sushi domains of mouse sp56.Using the 743 bp product as the probe to detect the expression profile of sp56 in rat tissues,Northern blot shows that a-2.0kb mRNA expresses specifically in testis.Employed the RACE method,two full cDNA sequences of rat sp56 were obtained.A Mr-42KD band was detected in denatured and non-reducing protein sample of rat testis and sperm with anti-mouse sp56 monoclonal antibody by Western blot method.Rat sp56 was localized on rat sperm head by the indirect immunofluorescence method.Rat sp56 immunoreactivity was detected from the early pachytene spermatocytes and throughout the spermatogenesis.Its cloning will further our understanding of the mechanism of the sperm-egg recognition and binding.     

Is there sperm storage in the clam shrimp Eulimnadia texana?

Abstract. Androdioecy is a rare form of mating system in which species comprise males and hermaphrodites. One recently described case of androdioecy is the freshwater crustacean Eulimnadia texana. A mathematical model of the mating system of this shrimp suggests that males and hermaphrodites should only coexist under limited circumstances. One possible factor not considered in this model would extend the conditions for coexistence: the possibility of sperm storage in the hermaphrodites. Here we use genetically marked matings between males and hermaphrodites to determine if hermaphrodites can store male sperms. Eggs were collected from hermaphrodites both in the presence of a male and after the male was removed. A total of 30 of these matings had successful hatches, but only 14 of these 30 could be used to test for sperm storage. In these 14 cases, an average of 35% of the eggs were outcrossed when males were present, but only 0.4% were outcrossed after males were removed. Thus, sperm storage by hermaphrodites was an insignificant factor in the production of offspring. These data suggest that sperm storage cannot help explain the coexistence of males and hermaphrodites in natural populations of this crustacean.     

Morphology of the male reproductive system,sperm ultrastructure and γ-irradiation of the red palm weevil Rhynchophorus ferrugineus Oliv. (Coleoptera: Dryophthoridae)

In the present study we describe the morphology of the male reproductive apparatus and sperm ultrastructure of the red palm weevil – an invasive pest of several palm tree species – as well as the most important steps of spermatogenesis. The reproductive apparatus consists of a pair of testes (each formed by two lobes) a long tube-like accessory gland, a prostate gland and a small accessory gland. Characteristic features of the sperm are 90–100 μm total length, 10 μm nucleus, two mitochondrial derivatives, two accessory bodies, one well-developed puff-like structure and a typical insect 9+9+2 flagellar axoneme. One of the methods used for the biological control of pests is the Sterile Insect Technique (SIT), for the evaluation of which we make a preliminary comparison of the sperm ultrastructure of non-irradiated and irradiated weevils (at a dose of 80 Gray).     

Identification of sperm morphometric subpopulations in the canine ejaculate: do they reflect different subpopulations in sperm chromatin integrity?

A statistical approach using sequentially principal component analysis (PCA) clustering and discriminant analysis was developed to disclose morphometric sperm subpopulations. In addition, we used a similar approach to disclose subpopulations of spermatozoa with different degrees of DNA fragmentation. It is widely accepted that sperm morphology is a strong indicator of semen quality and since the sperm head mainly comprises the sperm DNA, it has been proposed that subtle changes in sperm head morphology may be related to abnormal DNA content. Semen from four mongrel dogs (five replicates per dog) were used to investigate DNA quality by means of the sperm chromatin structure assay (SCSA), and for computerized sperm morphometry (ASMA). Each sperm head was measured for nine primary parameters: head area (A), head perimeter (P), head length (L), head width (W), acrosome area (%), midpiece width (w), midpiece area (a), distance (d) between the major axes of the head and midpiece, angle (theta) of divergence of the midpiece from the head axis; and four parameters of head shape: FUN1 (L/W), FUN2 (4pi A/P2), FUN3 ((L - W)/(L + W)) and FUN 4 (pi LW/4A). The data matrix consisted of 2361 observations, (morphometric analysis on individual spermatozoa) and 63,815 observations for the DNA integrity. The PCA analysis revealed five variables with Eigen values over 1, representing more than 79% of the cumulative variance. The morphometric data revealed five sperm subpopulations, while the DNA data gave six subpopulations of spermatozoa with different DNA integrity. Significant differences were found in the percentage of spermatozoa falling in each cluster among dogs (p < 0.05). Linear regression models including sperm head shape factors 2, 3 and 4 predicted the amount of denatured DNA within each individual spermatozoon (p < 0.001). We conclude that the ASMA analysis can be considered a powerful tool to improve the spermiogram.     

GAR22β regulates cell migration,sperm motility,and axoneme structure

Spatiotemporal cytoskeleton remodeling is pivotal for cell adhesion and migration. Here we investigated the function of Gas2-related protein on chromosome 22 (GAR22β), a poorly characterized protein that interacts with actin and microtubules. Primary and immortalized GAR22β^−/− Sertoli cells moved faster than wild-type cells. In addition, GAR22β^−/− cells showed a more prominent focal adhesion turnover. GAR22β overexpression or its reexpression in GAR22β^−/− cells reduced cell motility and focal adhesion turnover. GAR22β–actin interaction was stronger than GAR22β–microtubule interaction, resulting in GAR22β localization and dynamics that mirrored those of the actin cytoskeleton. Mechanistically, GAR22β interacted with the regulator of microtubule dynamics end-binding protein 1 (EB1) via a novel noncanonical amino acid sequence, and this GAR22β–EB1 interaction was required for the ability of GAR22β to modulate cell motility. We found that GAR22β is highly expressed in mouse testes, and its absence resulted in reduced spermatozoa generation, lower actin levels in testes, and impaired motility and ultrastructural disorganization of spermatozoa. Collectively our findings identify GAR22β as a novel regulator of cell adhesion and migration and provide a foundation for understanding the molecular basis of diverse cytoskeleton-dependent processes.