Showing papers on "Sperm published in 2009"

Sperm morphological diversity

Abstract: Publisher Summary This chapter reviews the current knowledge of variation in sperm morphology over several levels of biological organization: variation within males (both within and across ejaculates), among males, among populations, and among species, along with prevailing hypotheses addressing the adaptive significance of such variation. With regard to developmental mechanisms, three aspects of the physiology of sperm production serve to limit within-ejaculate variation in sperm phenotypes. First, the location of the testes and numerous aspects of testicular physiology of some taxa are clearly adaptations to maintain a homeostatic developmental environment for sperm. Second, developing spermatids may share cytoplasm. Third, sperm phenotypes are predominantly determined by testicular gene expression and hence the diploid genome of the male. Variation across ejaculates but within males can involve several traits including sperm numbers, overall semen quality and individual sperm quality. A special case of intramale variation in sperm form is found in species with sperm heteromorphism, in which different sperm forms are regularly produced by individuals. Differences among males in sperm morphology may derive from both genetic and environmental influences. Theories of condition-dependence basically posit that fitness-related traits are to a large extent dependent on an organism's underlying condition. Conclusions drawn from studies of sperm diversification between natural populations are reinforced by experimental evolution studies of sperm morphology in laboratory populations, as these studies address the evolvability of sperm traits and the nature of selection underlying sperm diversification. Furthermore, a discussion of evolutionary causes and consequences of sperm diversification, along with suggestions of fruitful areas for future exploration is presented.

Sperm biology : an evolutionary perspective

Abstract: This book represents the first analysis of the evolutionary significance of sperm phenotypes and derived sperm traits and the possible selection pressures responsible for sperm-egg coevolution. An understanding of sperm evolution is fast developing and promises to shed light on many topics from basic reproductive biology to the evolutionary process itself as well as the sperm proteome, the sperm genome and the quantitative genetics of sperm. The Editors have identified 15 topics of current interest and biological significance to cover all aspects of this bizarre, fascinating and important subject. It comprises the most comprehensive and up-to-date review of the evolution of sperm and pointers for future research, written by experts in both sperm biology and evolutionary biology. The combination of evolution and sperm is a potent mix, and this is the definitive account. * The first review survey of this emerging field * Written by experts from a broad array of disciplines from the physiological and biomedical to the ecological and evolutionary * Sheds light on the intricacies of reproduction and the coevolution of sperm, egg and reproductive behavior

Cryopreservation of domestic animal sperm cells

Abstract: Sperm cells are the endpoint of male spermatogenesis and have particular anatomic and metabolic features. Sperm cryopreservation and storage currently require liquid nitrogen or ultralow refrigeration methods for long or short term storage, which requires routine maintenance and extensive space requirements. Conserving sperms have several purposes such as artificial reproductive technologies (ART), species conservation and clinical medicine. The combinations of storage temperature, cooling rate, chemical composition of the extender, cryoprotectant concentration, reactive oxygen species (ROS), seminal plasma composition and hygienic control are the key factors that affect the life-span of spermatozoa. Sperm preservation protocols vary among animal species owing to their inherent particularities that change extenders used for refrigeration and freezing. Extenders for freezing sperm cells contain buffers, carbohydrates (glucose, lactose, raffinose, saccharose and trehalose), salts (sodium citrate, citric acid), egg yolk and antibiotics. The use of different cryoprotectants, like trehalose or glycerol, as well as different concentrations of egg yolk and other constituents in semen extenders are being studied in our laboratory. Several cooling rates have been tested to freeze sperm cells. The use of faster rates (15-60 degrees C/min) gives rise to best sperm survivals after freezing-thawing, but more studies are needed to find the adequate cooling rates for each animal species. Sheep and goat males of some native breeds are being used in studies performed in EZN. Semen from those males has been frozen and stored as part of the Portuguese Animal Germplasm Bank. In small ruminants, individual variations in the quality of frozen semen have been observed, suggesting specific differences in sperm susceptibility to freezing methods, particularly obvious in goat males. Best quality frozen semen from small ruminants is being used in cervical artificial insemination studies aiming to increase productive parameters in selected flocks.

Disruption of the pollen-expressed FERONIA homologs ANXUR1 and ANXUR2 triggers pollen tube discharge.

Abstract: The precise delivery of male to female gametes during reproduction in eukaryotes requires complex signal exchanges and a flawless communication between male and female tissues. In angiosperms, molecular mechanisms have recently been revealed that are crucial for the dialog between male (pollen tube) and female gametophytes required for successful sperm delivery. When pollen tubes reach the female gametophyte, they arrest growth, burst and discharge their sperm cells. These processes are under the control of the female gametophyte via the receptor-like serine-threonine kinase (RLK) FERONIA (FER). However, the male signaling components that control the sperm delivery remain elusive. Here, we show that ANXUR1 and ANXUR2 (ANX1, ANX2), which encode the closest homologs of the FER-RLK in Arabidopsis, are preferentially expressed in pollen. Moreover, ANX1-YFP and ANX2-YFP fusion proteins display polar localization to the plasma membrane at the tip of the pollen tube. Finally, genetic analyses demonstrate that ANX1 and ANX2 function redundantly to control the timing of pollen tube discharge as anx1 anx2 double-mutant pollen tubes cease their growth and burst in vitro and fail to reach the female gametophytes in vivo. We propose that ANX-RLKs constitutively inhibit pollen tube rupture and sperm discharge at the tip of growing pollen tubes to sustain their growth within maternal tissues until they reach the female gametophytes. Upon arrival, the female FER-dependent signaling cascade is activated to mediate pollen tube reception and fertilization, while male ANX-dependent signaling is deactivated, enabling the pollen tube to rupture and deliver its sperm cells to effect fertilization.

Mitochondrial glutathione peroxidase 4 disruption causes male infertility

Abstract: Selenium is linked to male fertility. Glutathione peroxidase 4 (GPx4), first described as an antioxidant enzyme, is the predominant selenoenzyme in testis and has been suspected of being vital for spermatogenesis. Cytosolic, mitochondrial, and nuclear isoforms are all encoded by the same gene. While disruption of entire GPx4 causes early embryonic lethality in mice, inactivation of nuclear GPx4 does not impair embryonic development or fertility. Here, we show that deletion of mitochondrial GPx4 (mGPx4) allows both normal embryogenesis and postnatal development, but causes male infertility. Infertility was associated with impaired sperm quality and severe structural abnormalities in the midpiece of spermatozoa. Knockout sperm display higher protein thiol content and recapitulate features typical of severe selenodeficiency. Interestingly, male infertility induced by mGPx4 depletion could be bypassed by intracytoplasmic sperm injection. We also show for the first time that mGPx4 is the prevailing GPx4 product in male germ cells and that mGPx4 disruption has no effect on proliferation or apoptosis of germinal or somatic tissue. Our study finally establishes that mitochondrial GPx4 confers the vital role of selenium in mammalian male fertility and identifies cytosolic GPx4 as the only GPx4 isoform being essential for embryonic development and apoptosis regulation.

Role of antioxidants in the treatment of male infertility

Abstract: Male infertility continues to be a clinical challenge of increasing significance. While male factors such as decreased semen quality are responsible for 25% of all infertility issues, the etiology of suboptimal semen quality is poorly understood. Many physiological, environmental, and genetic factors have been implicated, including oxidative stress. Oxidative stress is induced by reactive oxygen species (ROS), or free radicals, and although ROS are required for critical aspects of sperm function, excessive levels of ROS can negatively impact sperm quality. The origin of ROS generation, and the etiologies of increased ROS in men with suboptimal sperm quality have only recently been elucidated, offering multiple targets for potential therapy. Here, we present a critical review of the literature describing the role of oxidative stress on decreased sperm function, as well as the role of antioxidants in the treatment of male factor infertility.

Reduced amounts and abnormal forms of phospholipase C zeta (PLCzeta) in spermatozoa from infertile men.

Abstract: human infertility appear to be caused by failure of the sperm to activate and this may be due to specific defects in PLCz. methods and results: Immunofluorescence studies showed PLCz to be localized in the equatorial region of sperm from fertile men, but sperm deficient in oocyte activation exhibited no specific signal in this same region. Immunoblot analysis revealed reduced amounts of PLCz in sperm from infertile men, and in some cases, the presence of an abnormally low molecular weight form of PLCz .I n one non-globozoospermic case, DNA analysis identified a point mutation in the PLCz gene that leads to a significant amino acid change in the catalytic region of the protein. Structural modelling suggested that this defect may have important effects upon the structure and function of the PLCz protein. cRNA corresponding to mutant PLCz failed to induce calcium oscillations when microinjected into mouse oocytes. Injection of infertile human sperm into mouse oocytes failed to activate the oocyte or trigger calcium oscillations. Injection of such infertile sperm followed by two calcium pulses, induced by assisted oocyte activation, activated the oocytes without inducing the typical pattern of calcium oscillations. conclusions: Our findings illustrate the importance of PLCz during fertilization and suggest that mutant forms of PLCz may underlie certain types of human male infertility.

Female promiscuity promotes the evolution of faster sperm in cichlid fishes.

Abstract: Sperm competition, the contest among ejaculates from rival males to fertilize ova of a female, is a common and powerful evolutionary force influencing ejaculate traits. During competitive interactions between ejaculates, longer and faster spermatozoa are expected to have an edge; however, to date, there has been mixed support for this key prediction from sperm competition theory. Here, we use the spectacular radiation of cichlid fishes from Lake Tanganyika to examine sperm characteristics in 29 closely related species. We provide phylogenetically robust evidence that species experiencing greater levels of sperm competition have faster-swimming sperm. We also show that sperm competition selects for increases in the number, size, and longevity of spermatozoa in the ejaculate of a male, and, contrary to expectations from theory, we find no evidence of trade-offs among sperm traits in an interspecific analysis. Also, sperm swimming speed is positively correlated with sperm length among, but not within, species. These different responses to sperm competition at intra- and interspecific levels provide a simple, powerful explanation for equivocal results from previous studies. Using phylogenetic analyses, we also reconstructed the probable evolutionary route of trait evolution in this taxon, and show that, in response to increases in the magnitude of sperm competition, the evolution of sperm traits in this clade began with the evolution of faster (thus, more competitive) sperm.

Understanding the molecular basis of sperm capacitation through kinase design

Abstract: Thirty years ago, on July 25, Steptoe and Edwards reported the birth of Louise Joy Brown, the first successful “Test-Tube” baby (1). This achievement followed a lack of success of in vitro fertilization experiments for almost 80 years since the first attempts in 1878. These early failures were due mainly to a lack of comprehension of sperm physiology. In the early 1950s, Chang (2) and Austin (3) demonstrated independently that sperm had to be in the female reproductive tract for a finite period before acquiring fertilizing capacity. This phenomenon is known as sperm capacitation. What made this finding a necessary step for the consequent development of in vitro fertilization was the understanding that certain factors in the female were needed for the sperm to become fertile. A logical follow-up of the discovery of sperm capacitation occurred some years later when Chang demonstrated mammalian in vitro fertilization conclusively by showing that eggs from a black rabbit fertilized in vitro by capacitated sperm from a black male, and transferred to a white female, resulted in the birth of a litter of black offspring (4).

6 – Sperm competition and sperm phenotype

Abstract: Publisher Summary Sperm competition is the competition between the ejaculates of different males for the fertilization of a given set of ova. Charles Darwin (1871) proposed sexual selection as a process that operates on variation in male ability to compete with other males for access to reproductive opportunities, and which promotes traits that confer an advantage in reproductive competition. In most taxa individual females may copulate (or spawn) with multiple males (i.e., are polyandrous). As a consequence, the ejaculates of different males may co-occur around a set of ova at the time of fertilization, resulting in sperm competition. Sperm competition introduces variation in male reproductive success determined by the relative competitive fertilizing efficiency of the ejaculates of different males, and generates postcopulatory, intrasexual selection, which promotes traits that increase the fertilization success of an ejaculate under competitive conditions. A second consequence of polyandry is the potential for intersexual selection to continue after copulation through mechanisms that enable females (or ova) to bias the outcome of sperm competition in favor of the sperm of certain males, a process known as sperm selection or cryptic female choice. The past three decades have seen an explosion of interest in postcopulatory sexual selection that has highlighted the importance of sperm competition and cryptic female choice as engines of evolutionary change. This chapter reviews recent empirical and theoretical advances to discuss various ways in which sperm competition may shape the evolution of sperm and ejaculate traits.

Oxidative DNA damage impairs global sperm DNA methylation in infertile men.

Abstract: Purpose Methylation of sperm DNA is impaired in many infertile men potentially adversely effecting reproductive outcomes. In somatic cells oxidative damage to DNA and hyperhomocysteinaemia are linked with DNA hypomethylation. The objective of this study was to investigate if these pathologies also impair sperm DNA methylation.

Sperm morphology and sperm velocity in passerine birds

Abstract: Sperm velocity is one of the main determinants of the outcome of sperm competition Since sperm vary considerably in their morphology between and within species, it seems likely that sperm morphology is associated with sperm velocity Theory predicts that sperm velocity may be increased by enlarged midpiece (energetic component) or flagellum length (kinetic component), or by particular ratios between sperm components, such as between flagellum length and head size However, such associations have rarely been found in empirical studies In a comparative framework in passerine birds, we tested these theoretical predictions both across a wide range of species and within a single family, the New World blackbirds (Icteridae) In both study groups, sperm velocity was influenced by sperm morphology in the predicted direction Consistent with theoretical models, these results show that selection on sperm morphology and velocity are likely to be concomitant evolutionary forces

Epididymis seleno-independent glutathione peroxidase 5 maintains sperm DNA integrity in mice

Abstract: The mammalian epididymis provides sperm with an environment that promotes their maturation and protects them from external stresses. For example, it harbors an array of antioxidants, including non-conventional glutathione peroxidase 5 (GPX5), to protect them from oxidative stress. To explore the role of GPX5 in the epididymis, we generated mice that lack epididymal expression of the enzyme. Histological analyses of Gpx5-/- epididymides and sperm cells revealed no obvious defects. Furthermore, there were no apparent differences in the fertilization rate of sexually mature Gpx5-/- male mice compared with WT male mice. However, a higher incidence of miscarriages and developmental defects were observed when WT female mice were mated with Gpx5-deficient males over 1 year old compared with WT males of the same age. Flow cytometric analysis of spermatozoa recovered from Gpx5-null and WT male mice revealed that sperm DNA compaction was substantially lower in the cauda epididymides of Gpx5-null animals and that they suffered from DNA oxidative attacks. Real-time PCR analysis of enzymatic scavengers expressed in the mouse epididymis indicated that the cauda epididymidis epithelium of Gpx5-null male mice mounted an antioxidant response to cope with an excess of ROS. These observations suggest that GPX5 is a potent antioxidant scavenger in the luminal compartment of the mouse cauda epididymidis that protects spermatozoa from oxidative injuries that could compromise their integrity and, consequently, embryo viability.

Ca2+-stores in sperm: their identities and functions

Abstract: Intracellular Ca2+ stores play a central role in the regulation of cellular [Ca2+](i) and the generation of complex [Ca2+] signals such as oscillations and waves. Ca2+ signalling is of particular significance in sperm cells, where it is a central regulator in many key activities (including capacitation, hyperactivation, chemotaxis and acrosome reaction) yet mature sperm lack endoplasmic reticulum and several other organelles that serve as Ca2+ stores in somatic cells. Here, we review i) the evidence for the expression in sperm of the molecular components (pumps and channels) which are functionally significant in the activity of Ca2+ stores of somatic cells and ii) the evidence for the existence of functional Ca2+ stores in sperm. This evidence supports the existence of at least two storage organelles in mammalian sperm, one in the acrosomal region and another in the region of the sperm neck and midpiece. We then go on to discuss the probable identity of these organelles and their discrete functions: regulation by the acrosome of its own secretion and regulation by membranous organelles at the sperm neck (and possibly by the mitochondria) of flagellar activity and hyperactivation. Finally, we consider the ability of the sperm discretely to control mobilisation of these stores and the functional interaction of stored Ca2+ at the sperm neck/midpiece with CatSper channels in the principal piece in regulation of the activities of mammalian sperm.

Removal of spermatozoa with externalized phosphatidylserine from sperm preparation in human assisted medical procreation: effects on viability, motility and mitochondrial membrane potential

Abstract: Externalization of phosphatidylserine (EPS) occurs in apoptotic-like spermatozoa and could be used to remove them from sperm preparations to enhance sperm quality for assisted medical procreation. We first characterized EPS in sperms from infertile patients in terms of frequency of EPS spermatozoa as well as localization of phosphatidylserine (PS) on spermatozoa. Subsequently, we determined the impact of depleting EPS spermatozoa on sperm quality. EPS were visualized by fluorescently-labeled annexin V binding assay. Double staining with annexin V and Hoechst differentiates apoptotic from necrotic spermatozoa. We used magnetic-activated cell sorting using annexin V-conjugated microbeads (MACS-ANMB) technique to remove EPS spermatozoa from sperm prepared by density gradient centrifugation (DGC). The impact of this technique on sperm quality was evaluated by measuring progressive motility, viability, and the integrity of the mitochondrial membrane potential (MMP) by Rhodamine 123. Mean percentages of EPS spermatozoa were 14% in DGC sperm. Four subpopulations of spermatozoa were identified: 70% alive, 3% early apoptotic, 16% necrotic and 11% late apoptotic or necrotic. PS were localized on head and/or midpiece or on the whole spermatozoa. MACS efficiently eliminates EPS spermatozoa. MACS combined with DGC allows a mean reduction of 70% in EPS and of 60% in MMP-disrupted spermatozoa with a mean increase of 50% in sperm survival at 24 h. Human ejaculates contain EPS spermatozoa which can mostly be eliminated by DGC plus MACS resulting in improved sperm long term viability, motility and MMP integrity. EPS may be used as an indicator of sperm quality and removal of EPS spermatozoa may enhance fertility potential in assisted medical procreation.

The presence of bacteria species in semen and sperm quality.

Abstract: To verify the prevalence of semen bacterial contamination and whether the contamination could decrease sperm quality. Spermiogram, semen culture, and sperm transmission electron microscopy (TEM) analysis were performed. TEM data were elaborated using a mathematical formula that calculates a fertility index (FI)—able to define patients as fertile or infertile—and the percentage of sperm apoptosis, immaturity and necrosis. We aligned the amino acid sequence of beta-tubulin with protein of the most frequent species isolated from semen. Patients were divided according to the contaminating species; in each group, we observed fertile individuals, in whom the semen quality was similar to that of controls and infertile men whose sperm quality was significantly decreased, in terms of motility, FI, apoptosis and necrosis. Partial homology between β-tubulin and bacterial proteins was observed. Sperm bacterial contamination is quite frequent and could contribute to the deterioration of the sperm quality of infertile men.

Reactive Oxygen Species and Boar Sperm Function

Abstract: Boar spermatozoa are very susceptible to reactive oxygen species (ROS), but ROS involvement in damage and/or capacitation is unclear. The impact of exposing fresh boar spermatozoa to an ROS-generating system (xanthine/xanthine oxidase; XA/XO) on sperm ROS content, membrane lipid peroxidation, phospholipase (PL) A activity, and motility, viability, and capacitation was contrasted to ROS content and sperm function after cryopreservation. Exposing boar sperm (n = 4-5 ejaculates) to the ROS-generating system for 30 min rapidly increased hydrogen peroxide (H2O2) and lipid peroxidation in all sperm, increased PLA in dead sperm, and did not affect intracellular O2- (flow cytometry of sperm labeled with 2',7'-dichlorodihydrofluorscein diacetate, BODIPY 581/591 C11, bis-BODIPY-FL C11, hydroethidine, respectively; counterstained for viability). Sperm viability remained high, but sperm became immotile. Cryopreservation decreased sperm motility, viability, and intracellular O2- significantly, but did not affect H2O2. As expected, more sperm incubated in capacitating media than Beltsville thawing solution buffer underwent acrosome reactions and protein tyrosine phosphorylation (four proteins, 58-174 kDa); which proteins were tyrosine phosphorylated was pH dependent. Pre-exposing sperm to the ROS-generating system increased the percentage of sperm that underwent acrosome reactions after incubation in capacitating conditions (P < 0.025), and decreased capacitation-dependent increases in two tyrosine-phosphorylated proteins (P < or = 0.035). In summary, H2O2 is the major free radical mediating direct ROS effects, but not cryopreservation changes, on boar sperm. Boar sperm motility, acrosome integrity, and lipid peroxidation are more sensitive indicators of oxidative stress than viability and PLA activity. ROS may stimulate the acrosome reaction in boar sperm through membrane lipid peroxidation and PLA activation.

Zinc is an essential trace element for spermatogenesis

Abstract: Zinc (Zn) plays important roles in various biological activities but there is little available information regarding its functions in spermatogenesis. In our current study, we further examined the role of Zn during spermatogenesis in the Japanese eel (Anguilla japonica). Human CG (hCG) was injected into the animals to induce spermatogenesis, after which the concentration of Zn in the testis increased in tandem with the progression of spermatogenesis. Staining of testicular cells with a Zn-specific fluorescent probe revealed that Zn accumulates in germ cells, particularly in the mitochondria of spermatogonia and spermatozoa. Using an in vitro testicular organ culture system for the Japanese eel, production of a Zn deficiency by chelation with N,N,N′,N′-tetrakis (2-pyridylemethyl)ethylenediamine (TPEN) caused apoptosis of the germ cells. However, this cell death was rescued by the addition of Zn to the cultures. Furthermore, an induced deficiency of Zn by TPEN chelation was found to inhibit the germ cell proliferation induced by 11-ketotestosterone (KT), a fish specific androgen, 17α,20β-dihydroxy-4-pregnen-3-one (DHP), the initiator of meiosis in fish, and estradiol-17β (E2), an inducer of spermatogonial stem-cell renewal. We also investigated the effects of Zn deficiency on sperm motility and observed that TPEN treatment of eel sperm suppressed the rate and duration of their motility but that co-treatment with Zn blocked the effects of TPEN. Our present results thus suggest that Zn is an essential trace element for the maintenance of germ cells, the progression spermatogenesis, and the regulation of sperm motility.

Speciation and the evolution of gamete recognition genes: pattern and process

Abstract: Proteins on gamete surfaces are major determinants of fertilization success, particularly in free-spawning animals. Molecular analyses of these simple genetic systems show rapid evolution, positive selection, accelerated coalescence and, sometimes, extensive polymorphism. Careful analysis of the behavior of sperm produced by males with different gamete alleles shows that these alleles can deliver significant functional differences. Three forms of allele-specific fertilization advantage have been shown: assortative mating based on gamete type, rare allele advantage and heterozygote superiority. Models suggest that sperm and egg proteins may be coevolutionary partners that can alternate between directional selection for high fertilization ability and cyclic adaptation of eggs and sperm driven by sexual conflict. These processes act within allopatric populations and may accelerate their divergence if gamete adaptations in separate demes reduce cross-fertilization. Reproductive character displacement by reinforcement may play a diversifying role when previously allopatric populations rejoin. In circumstance that might prove to be common, divergence in sympatry can be driven by sexual conflict or by association of mating types with ecological differences. The ecology of fertilization, especially the degree of sperm competition and egg death via polyspermy, are important determinants of the strength and direction of selection on gametes. Free-spawning animals allow careful analysis of gamete recognition -from the behavior of adults and interactions of gametes, to molecular patterns of allele divergence. Future research efforts on the evolutionary consequences of fertilization ecology, and the interaction between extensive variation in egg surface proteins and sperm fertilization ability, are particularly needed.

Cigarette smoke extract immobilizes human spermatozoa and induces sperm apoptosis.

Abstract: Cigarette smoking by the male partner adversely affects assisted reproductive techniques, suggesting that it may damage sperm chromatin/DNA and consequently embryo development. The effects of graded concentrations of research cigarettes smoke extract (CSE) on motility, mitochondrial membrane potential (MMP), chromatin integrity and apoptosis were evaluated in spermatozoa obtained from 13 healthy, non-smoking men with normal sperm parameters, by flow cytometry. CSE suppressed sperm motility in a concentration- and time-dependent manner and increased the number of spermatozoa with low MMP, the main source of energy for sperm motility. In addition, CSE had a detrimental effect on sperm chromatin condensation and apoptosis. Indeed, it increased the number of spermatozoa with phosphatidylserine externalization, an early apoptotic sign, and fragmented DNA, a late apoptotic sign, in a concentration- and time-dependent manner. These effects of CSE were of similar or even greater magnitude to those obtained following incubation with tumour necrosis factor-α, a cytokine known for its negative impact on sperm function, used as positive control. Since transmission of smoking-induced sperm DNA alterations has been found in pre-implantation embryos, and this may predispose offspring to a greater risk of malformations, cancer and genetic diseases, men seeking to father a child are recommended to give up smoking.

Ejaculate–female and sperm–female interactions

Abstract: Publisher Summary The mechanisms of sexual reproduction are expected to be complex and evolutionarily dynamic in internally fertilizing species, where numerous biochemical, physiological, morphological, and behavioral mechanisms mediate insemination, sperm migration, sperm storage, the maintenance of sperm viability, and sperm modification, all of which must be properly executed before fertilization can begin. This situation provides the opportunity for postcopulatory sexual selection, which is predicted to further enhance complexity and diversification in genes contributing to differential male fertilization success and female control over paternity. It is becoming increasingly clear that sperm and ejaculate constituents evolve in response to selection pressures imposed by the female reproductive tract. Ejaculate–female interactions (EFIs) can determine whether or not a reproductive attempt is successful and can influence the outcome of sperm competition within populations. Evolutionary diversification of EFIs may further determine the extent of reproductive isolation and gene introgression between closely related species. This chapter aims to illustrate the pervasiveness of EFIs by discussing different types and what is known about their underlying mechanisms, and it considers the evolutionary significance of EFIs. Furthermore the chapter reviews evidence for rapid evolutionary diversification of EFI genes, correlated evolution of sex-specific EFI traits, and the relationship between genetic compatibility, male–female interactions, and patterns of sperm precedence.

Sperm cell proteomics.

Abstract: The spermatozoon is an accessible cell which can be easily purified and therefore it is particularly well suited for proteomic analysis. It is also an extremely differentiated cell with very marked genetic, cellular, functional and chromatin changes as compared to other cells, and has profound implications for fertility, embryo development and heredity. The recent developments in MS have boosted the potential for identification and study of the sperm proteins. Catalogues of hundreds to thousands of spermatozoan proteins in human and in model species are becoming available setting up the basis for subsequent research, diagnostic applications and the development of specific treatments. The present article reviews the available scientific publications dealing with the composition and function of the sperm cell using an MS proteomic approach.

A plant germline-specific integrator of sperm specification and cell cycle progression.

Abstract: The unique double fertilisation mechanism in flowering plants depends upon a pair of functional sperm cells. During male gametogenesis, each haploid microspore undergoes an asymmetric division to produce a large, non-germline vegetative cell and a single germ cell that divides once to produce the sperm cell pair. Despite the importance of sperm cells in plant reproduction, relatively little is known about the molecular mechanisms controlling germ cell proliferation and specification. Here, we investigate the role of the Arabidopsis male germline-specific Myb protein DUO POLLEN1, DUO1, as a positive regulator of male germline development. We show that DUO1 is required for correct male germ cell differentiation including the expression of key genes required for fertilisation. DUO1 is also necessary for male germ cell division, and we show that DUO1 is required for the germline expression of the G2/M regulator AtCycB1;1 and that AtCycB1:1 can partially rescue defective germ cell division in duo1. We further show that the male germline-restricted expression of DUO1 depends upon positive promoter elements and not upon a proposed repressor binding site. Thus, DUO1 is a key regulator in the production of functional sperm cells in flowering plants that has a novel integrative role linking gametic cell specification and cell cycle progression.