Seminal plasmin

CRISPR/Cas9 Mediated Disruption of Seminal Fluid Protein Sfp62 Induces Male Sterility in Bombyx mori

Simple Summary

In gamogenetic animals, seminal fluid proteins are essential for male fertility. In this study, we investigated the function of the seminal fluid protein Sfp62 by using the CRISPR/Cas9 system in lepidopteran model insect Bombyx mori. Sfp62 mutation led to male sterility and can be inherited stably. The mutation did not affect growth and developmental nor female fertility. These data indicate that Sfp62 is an ideal target for sterile insect technology (SIT), in which genetically modified insects are released on a large scale to mate with wild-type insects in order to reduce or even eradicate the target pests. The determining factors for the effective implementation of SIT include the strong competitiveness of the modified individuals and multi-generational effects resulting from the mutation. Sfp62 meets these criteria and is therefore a promising target for biological pest control.

Abstract

Seminal fluid proteins provide factors necessary for development, storage, and activation of sperm. Altered expression of seminal fluid proteins can lead to defect in male infertility. We investigated the function of seminal fluid protein Sfp62 in the model lepidopteran insect Bombyx mori using CRISPR/Cas9 mediated mutagenesis. The knockout of BmSfp62 gene led to male sterility but has no effect on female fertility. The mutation did not affect growth and development of the silkworm of both sexes. Motility of sperm in male mutants was decreased and the mRNA expression levels of other genes encoding seminal fluid proteins were altered in BmSfp62 mutants compared to the wild-type controls. The male sterility caused by mutation of BmSfp62 was stably inherited. As the proteins encoded by Sfp62 genes are conserved among lepidopteran species, Sfp62 is a potential target for the biological management of lepidopteran pests.

Seminal plasma and its effect on ruminant spermatozoa during processing

Seminal plasma can both inhibit and stimulate sperm function, making its use as a supportive medium somewhat contradictory. These effects are directed by the multifunctional action of numerous inorganic and organic components, but it is the direct association of seminal plasma proteins with the sperm membrane that is thought to exert the most significant response. In vitro handling of spermatozoa in preparation for artificial insemination may involve washing, dilution, cooling, freezing, re-warming and sex-sorting. These processes can alter proteins of the sperm surface and reduce seminal plasma in the sperm environment. This, among other factors, may destabilize the sperm membrane and reduce the fertilizable lifespan of spermatozoa. Such handling-induced damage may be prevented or reversed through supplementation of seminal plasma, but the effectiveness of this technique differs with species, and the source and subsequent treatment of both spermatozoa and seminal plasma. Seminal plasma appears to act as a protective medium during in vitro processing of ram spermatozoa, but this does not appear to be the case for bull spermatozoa. The reasons for this divergent effect will be discussed with particular emphasis on the influence of the major proteins of ruminant seminal plasma, known as BSP proteins. The biochemical and biophysical properties of these proteins are well documented, and this information has provided greater insight into the signalling pathways of capacitation and the protective action of extender components.

Involvement of Semenogelin-Derived Peptides in the Antibacterial Activity of Human Seminal Plasma1

Mechanisms for protecting spermatozoa, and the testes that produce them, from infection are essential, given the importance of these cells and organs for the fertility of the individual and perpetuation of the species. This is borne out by the publication of numerous papers on this subject over the last 50 years. We extended our work and that of others on the anti-infectious defense system of the male genital tract, using a new strategy for the direct identification of antibacterial molecules in human seminal plasma. We subjected a liquefied seminal plasma cationic fraction to reversed-phase HPLC, monitored microbicidal activity by gel overlay and radial diffusion assays, and identified the proteins and/or peptides present in each active fraction by mass spectrometry. In addition to proteins with known potent microbicidal activity--phospholipase A2, lactoferrin, and lysozyme--we also found that peptides produced by cleavage of semenogelin I, the predominant human semen coagulum protein, had high levels of antibacterial activity.

Induction of autophagic cell death in Leishmania donovani by antimicrobial peptides

We demonstrate that antimicrobial peptides induce an autophagic cell death in the protozoan pathogen, Leishmania donovani. In our study, three antimicrobial peptides, Indolicidin, and two peptides derived from Seminalplasmin exhibit antileishmanial activity with a 50% lethal dose of 3.5 x 10(-5), 3.8 x 10(-4) and 1.7 x 10(-8) microM, respectively. The action of these antimicrobial peptides on the Leishmania cell involves ionic interactions, which are modulated by lipophosphoglycan on the parasite's surface. Peptide treatment caused dissipation of membrane potential and equilibration of intracellular pH with extracellular environment. However, there was no release of intracellular GFP molecules upon peptide treatment of a GFP expressing Leishmania clone. Transmission electron microscopic studies show extensive intracellular damage including cytoplasmic vacuolization and degeneration of cellular organization without disruption of the plasma membrane. These peptides induce cell death via a non-apoptotic process as shown by lack of nuclear fragmentation or DNA laddering and independent of caspase-like activity. Instead, Monodansylcadaverine (MDC), a biochemical marker of autophagy specifically labels the vacuoles induced by peptides. Collectively, these results indicate that in addition to their effects on the leishmanial membrane, these antimicrobial peptides induce pathway(s) for autophagic cell death in L. donovani.

Localization of a proteolytic enzyme within the efferent and deferent duct epithelial cells of the turkey (Meleagris gallopavo) using immunohistochemistry

Turkey seminal plasma contains a serine protease found to be distinct from the spermatozoal acrosin. However, the origin and biological roles of this enzyme are unknown. Our experimental objective was to identify the cellular source of this protease within the male reproductive tract. The enzyme was isolated from seminal plasma using benzamidine-Sepharose 6B chromatography. A synthetic substrate, Nalpha-benzoyl-DL-arginine p-nitroanilide, was used to detect fractions containing the enzyme. The affinity chromatography technique yielded a 150-fold increase in amidase activity. Analysis of the protease by SDS-PAGE revealed two protein bands with relative molecular masses of 37 000 and 61 000. Proteolytic activity was detected within the smaller band as evidenced by casein digestion. Further analysis of the purified protein revealed that the smaller protein band was glycosylated. To determine the cellular source of the protease, a panel of mouse monoclonal antibodies was then developed against the purified protease, and used in immunohistochemistry. Frozen tissue sections from the liver, testis, epididymal region, and deferent duct were fixed in 4% (w/v) paraformaldehyde, permeabilized with 0.2% (v/v) (octylphenoxy)polyethoxyethanol followed by routine immunohistochemistry procedures. Monoclonal antibodies did not bind to tissue sections from either the liver or testis, or to blood plasma proteins. Both the distal portion of the efferent duct and the deferent duct were immunoreactive. We concluded that the protease found in turkey seminal plasma is concentrated to the distal efferent duct and the deferent duct epithelial cells.

The origin and evolution of peptide YY (PYY) and pancreatic polypeptide (PP)

It is generally accepted that the neuropeptide Y (NPY) family of homologous peptides arose as a result of a series of gene duplication events. Recent advances in comparative genomics allow to formulate a hypothesis that explains, at least in part, the complexity of the family. Chromosome mapping studies reveal that the gene encoding PYY may have arisen from a common ancestral gene (termed NYY) in an ancient chromosomal duplication event that also involved the hox gene clusters. A tandem duplication of the PYY gene concomitant with or just before the emergence of tetrapods generated the PPY gene encoding PP. In the primate and ungulate lineages, the PYY-PPY gene cluster has undergone a more recent gene duplication event to create a PYY2-PPY2 gene cluster on the same chromosome. In the human and baboon, this cluster probably does not encode functional NPY family peptides but expression of the bovine PYY2 gene generates seminalplasmin, a major biologically active component of bull semen. An independent duplication of the PYY gene in the lineage of teleost fish has generated peptides of the PY family that are synthesized in the pancreatic islets of Acanthomorpha. The structural organization of the biosynthetic precursors of PYY and PP (preproPYY and preproPP) has been quite well preserved during the evolution of vertebrates but conservative pressure on individual domains in the proteins has not been uniform. The duplication of the PYY gene that generated the PPY gene appears to have resulted in a relaxation of conservative pressure on the functional domain with the result that the amino acid sequences of tetrapod PYYs are more variable than the PYYs of jawed fish. Although the primary structure of PP has been quite strongly conserved in mammals, with the exception of the rodents, the extreme variability in the sequences of amphibian and reptilian PPs means that the peptide is a useful molecular marker to study the branching order in early tetrapod evolution

Drosophila males transfer antibacterial proteins from their accessory gland and ejaculatory duct to their mates

The male fruitfly, Drosophila melanogaster, transfers to his mate proteins that increase his reproductive success by causing changes in her behavior and physiology. Here we show that among the transferred proteins are ones with antibacterial activity. We performed Escherichia coli overlay assays of native PAGE or renatured SDS-PAGE of reproductive tissue extracts of wild-type or transgenic males deficient in accessory gland function. We detected a 28 kDa male accessory gland-derived protein and two ejaculatory duct-derived proteins all with antibacterial activity. Based on its gel mobility and tissue of synthesis, one of the ejaculatory duct proteins is likely to be andropin, a previously-reported 6 kDa antibacterial peptide. All three proteins are transferred to females during mating. Therefore, they could assist in protecting the male's reproductive tract and, after transfer to the female, the female's reproductive tract or eggs against bacterial infection. Since seminal fluid proteins are transferred before the sperm, these antibacterial proteins may also protect sperm from bacterial infection.

Antimicrobial peptides: properties and applicability

All organisms need protection against microorganisms, e. g. bacteria, viruses and fungi. For many years, attention has been focused on adaptive immunity as the main antimicrobial defense system. However, the adaptive immune system, with its network of humoral and cellular responses is only found in higher animals, while innate immunity is encountered in all living creatures. The turning point in the appreciation of the innate immunity was the discovery of antimicrobial peptides in the early eighties. In general these peptides act by disrupting the structural integrity of the microbial membranes. It has become clear that membrane-active peptides and proteins play a crucial role in both the innate and the adaptive immune system as antimicrobial agents. This review is focused on the functional and structural features of the naturally occurring antimicrobial peptides, and discusses their potential as therapeutics.

Interaction of antimicrobial peptides with biological and model membranes: structural and charge requirements for activity

Species right across the evolutionary scale from insects to mammals use peptides as part of their host-defense system to counter microbial infection. The primary structures of a large number of these host-defense peptides have been determined. While there is no primary structure homology, the peptides are characterized by a preponderance of cationic and hydrophobic amino acids. The secondary structures of many of the host-defense peptides have been determined by a variety of techniques. The acyclic peptides tend to adopt helical conformation, especially in media of low dielectric constant, whereas peptides with more than one disulfide bridge adopt beta-structures. Detailed investigations have indicated that a majority of these host-defense peptides exert their action by permeabilizing microbial membranes. In this review, we discuss structural and charge requirements for the interaction of endogenous antimicrobial peptides and short peptides that have been derived from them, with membranes.

Mechanism of antimicrobial action of indolicidin

Indolicidin, a 13-residue antimicrobial peptide isolated from cytoplasmic granules of bovine neutrophils, exhibits activity against Gram-positive and Gram-negative bacteria as well as fungi. Although indolicidin is bactericidal and permeabilizes the bacterial membranes, it does not lyse the bacterial cells. We examined the effect of bactericidal concentrations of indolicidin on the morphology of Escherichia coli cells and found that it induces filamentation. Further investigations showed that indolicidin inhibits DNA synthesis in E. coli cells at concentrations at which RNA and protein synthesis are either partially affected or not affected at all. Since inhibition of DNA synthesis is also known to induce filamentation in E. coli, it appears to contribute to the antimicrobial activity of indolicidin.

Structural features of helical aggregates of antibacterial peptides via simulated annealing and molecular modeling

A 27-residue stretch of amino acids encompassing two putative 13-residue amphiphilic helical segments is an important determinant of activity in the 47-residue antibacterial peptide bovine seminalplasmin. Synthetic peptides corresponding to the 27-residue stretch (P27) SLSRYAKLANRLANPKLLETFLSKWIG as well as the 13-residue segments PKLLETFLSKWIG (SPF),exhibit antimicrobial activity. An analog of SPF where E has been replaced by K(SPFK) showed improved antimicrobial properties as compared to SPF. The peptides have the ability to bind and permeabilize membranes. We have modeled helical bundles of P27 and the two 13-residue peptides SPF and SPFK using simulated annealing via molecular dynamics. Octameric but not hexameric aggregates of P27 can form channels which would allow the passage of ions. In the case of 13-residue peptides, aggregates formed by 6 monomers can conceivably form ion conducting channels. Since the ability to form channels which would allow the passage of ions across the membranes is an important determinant of the biological activities of these peptides, knowledge of the pore forming structures should help in the design of analogs with improved activities.