Identification of differentially expressed genes of primary spermatocyte against round spermatid isolated from human testis using the laser capture microdissection technique

Overexpression of 18S rRNA methyltransferase CrBUD23 enhances biomass and lutein content in Chlamydomonas reinhardtii

Post-transcriptional modification of nucleic acids including transfer RNA (tRNA), ribosomal RNA (rRNA) and messenger RNA (mRNA) is vital for fine-tunning of mRNA translation. Methylation is one of the most widespread post-transcriptional modifications in both eukaryotes and prokaryotes. HsWBSCR22 and ScBUD23 encodes a 18S rRNA methyltransferase that positively regulates cell growth by mediating ribosome maturation in human and yeast, respectively. However, presence and function of 18S rRNA methyltransferase in green algae are still elusive. Here, through bioinformatic analysis, we identified CrBUD23 as the human WBSCR22 homolog in genome of the green algae model organism Chlamydonomas reinhardtii. CrBUD23 was a conserved putative 18S rRNA methyltransferase widely exited in algae, plants, insects and mammalians. Transcription of CrBUD23 was upregulated by high light and down-regulated by low light, indicating its role in photosynthesis and energy metabolism. To characterize its biological function, coding sequence of CrBUD23 fused with a green fluorescence protein (GFP) tag was derived by 35S promoter and stably integrated into Chlamydomonas genome by glass bead-mediated transformation. Compared to C. reinhardtii wild type CC-5325, transgenic strains overexpressing CrBUD23 resulted in accelerated cell growth, thereby leading to elevated biomass, dry weight and protein content. Moreover, overexpression of CrBUD23 increased content of photosynthetic pigments but not elicit the activation of antioxidative enzymes, suggesting CrBUD23 favors growth and proliferation in the trade-off with stress responses. Bioinformatic analysis revealed the G1177 was the putative methylation site in 18S rRNA of C. reinhardtii CC-849. G1177 was conserved in other Chlamydonomas isolates, indicating the conserved methyltransferase activity of BUD23 proteins. In addition, CrTrm122, the homolog of BUD23 interactor Trm112, was found involved in responses to high light as same as CrBUD23. Taken together, our study revealed that cell growth, protein content and lutein accumulation of Chlamydomonas were positively regulated by the 18S rRNA methyltransferase CrBUD23, which could serve as a promising candidate for microalgae genetic engineering.

The emerging role of mitochondrial derived peptide humanin in the testis

The discovery of mitochondrial derive peptides (MDPs) has spotlighted mitochondria as central hubs in control and regulation of cell viability and metabolism in the testis in response to intracellular and extracellular stresses. MDPs (Humanin, MOTS-c and SHLP-2) are present in testes. Humanin, the first MDP, is predominantly expressed in Leydig cells, and moderately in germ cells and seminal plasma. The administration of synthetic humanin peptide agonist HNG protects male germ cells against apoptosis induced by intratesticular hormonal deprivation, testicular hyperthermia, and chemotherapeutic agents in rodent testes. Humanin interacting with IGFBP-3 and/or Bax (pro-apoptotic proteins) prevents the activation of germ cell apoptosis. Humanin participates in the network of IL-12/IL-27 family of cytokines to exert the immune-modulation of the testicular environment. Humanin and other MDPs may be important in the amelioration of testicular stress and prevention of cell injury with possible implications for male infertility, fertility preservation and contraceptive development.

The role of humanin in the regulation of reproduction

Humanin, a mitochondria-derived peptide, has been found to exert variously protective function in many tissues, especially in the nervous tissues. However, relatively limited studies have focused on the role of humanin in the regulation of reproduction. Current observations indicate that humanin plays an important role in regulating the response of the cell to oxidative stress and apoptosis in ovaries and testes via the modulation of several signaling pathways, especially when the body is in an abnormal state. Even so, the detailed mechanism of humanin function needs to be explored urgently. In this passage, we demonstrate how humanin exerts its protective role in female and male reproduction and raise several questions that need further investigations. Given humanin's new frontier for the design of novel therapeutic approaches for male infertility, male contraception, female infertility, and glucose metabolism in polycystic ovary syndrome, it is worthy of further study on its protective effects and clinical applications in reproductive function.

Reaction model and thermodynamic properties between sulfur-containing active groups and oxygen during coal self-heating

To further study the mechanism of coal self-heating, the reaction sequences and thermodynamic properties between sulfur-containing groups and oxygen during coal self-heating were analyzed. The benzyl mercaptan and diphenyl sulfide were selected as typical sulfur-containing structures existing in coal. Their structural parameters, frontier orbital characteristics, and thermodynamic parameters were analyzed through quantum chemistry calculation and their detailed reaction sequences with oxygen were proposed. The results indicate that the thiol structure in coal can easily react with oxygen at low temperatures and release large amounts of heat (146.70 kJ/mol) during coal self-heating, providing active free radicals and energy for subsequent chain reactions of coal spontaneous combustion. The oxidation reaction between the thioether structure and oxygen cannot occur at room temperature. With the accumulation of heat, thioether gradually becomes active and reacts with oxygen to form sulfoxide and release an enormous amount of heat (248.09 kJ/mol), which can be further oxidized to sulfone with an increase in temperature. The reaction models of thiol and thioether groups during coal self-heating were proposed, which involves eight main reaction sequences (R1∼R8). It indicates that the reactions of thiol and thioether groups play crucial roles during the evolution of coal self-heating, with a slow oxidation stage at low temperatures and an accelerated oxidation stage at high temperatures.

Structures of Pb-BHA Complexes Adsorbed on Scheelite Surface

Previous studies have shown that Pb-BHA complexes (lead complexes of benzohydroxamic acid) have better collecting ability and can be used in flotation experiments with BHA acting as a collector and lead ions acting as activators. However, the structures of Pb-BHA complexes adsorbed on a mineral surface remain unclear. In this work, the adsorption behavior of Pb-BHA complexes on the scheelite surface was studied by flotation experiments and adsorption capacity measurements, and the structures of the adsorbed Pb-BHA complexes were determined using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The adsorption capacity results showed that more BHA was adsorbed on the scheelite surface in Pb-BHA flotation, and the XPS and TOF-SIMS analysis showed that the species of Pb-BHA complexes adsorbed on the scheelite surface were similar in activation flotation and Pb-BHA flotation. Therefore, the different contents of the complexes on the scheelite surface were responsible for the flotation behavior. XPS and TOF-SIMS showed that BHA combined with lead ions to form complexes with different structures, such as five- and four-membered ring structures. Structure fragment inference based on the measurements indicated that lead ions formed monomer complexes with two BHAs, and that lead hydroxide polymers with a certain degree of polymerization bonded with oxygen atoms in the complexes. The Pb-BHA complexes combine with oxygen atoms on the scheelite surface to form an adsorbate, rendering the surface hydrophobic.

Humanin protects against chemotherapy-induced stage-specific male germ cell apoptosis in rats

Humanin (HN) has cytoprotective action on male germ cells after testicular stress induced by heat and hormonal deprivation. To examine whether HN has protective effects on chemotherapy-induced male germ cell apoptosis, we treated four groups of adult rats with (i) vehicle (control), (ii) HN, (iii) cyclophosphamide (CP); or (iv) HN+CP. To investigate whether the protective effects of HN on germ cells require the presence of Leydig cells, another four groups of rats were pre-treated with ethane dimethanesulfonate (EDS), a Leydig cell toxicant, to eliminate Leydig cells. After 3 days, when Leydig cells were depleted by EDS, we administered: (i) vehicle, (ii) HN, (iii) CP; or (iv) HN+CP to rats. All rats were killed 12 h after the injection of HN and/or CP. Germ cell apoptosis was detected by TUNEL assay and quantified by numerical count. Compared with control and HN (alone), CP significantly increased germ cell apoptosis; HN +CP significantly reduced CP-induced apoptosis at early (I-VI) and late stages (IX-XIV) but not at middle stages (VII-VIII) of the seminiferous epithelial cycle. Pre-treatment with EDS markedly suppressed serum and intratesticular testosterone (T) levels, and significantly increased germ cell apoptosis at the middle (VII-VIII) stages. CP did not further increase germ cell apoptosis in the EDS-pre-treated rats. HN significantly attenuated germ cell apoptosis at the middle stages in EDS pre-treated rats. To investigate whether HN has any direct effects on Leydig cell function, adult Leydig cells were isolated and treated with ketoconazole (KTZ) to block testosterone synthesis. HN was not effective in preventing the reduction of T production by KTZ in vitro. We conclude that HN decreases CP and/or EDS-induced germ cell apoptosis in a stage-specific fashion. HN acts directly on germ cells to protect against EDS-induced apoptosis in the absence of Leydig cells and intratesticular testosterone levels are very low.

Identification of male gametogenesis expressed genes from the scallop Nodipecten subnodosus by suppressive subtraction hybridization and pyrosequencing

Despite the great advances in sequencing technologies, genomic and transcriptomic information for marine non-model species with ecological, evolutionary, and economical interest is still scarce. In this work we aimed to identify genes expressed during spermatogenesis in the functional hermaphrodite scallop Nodipecten subnodosus (Mollusca: Bivalvia: Pectinidae), with the purpose of obtaining a panel of genes that would allow for the study of differentially transcribed genes between diploid and triploid scallops in the context of meiotic arrest and reproductive sterility. Because our aim was to isolate genes involved in meiosis and other testis maturation-related processes, we generated suppressive subtractive hybridization libraries of testis vs. inactive gonad. We obtained 352 and 177 ESTs by clone sequencing, and using pyrosequencing (454-Roche) we maximized the identified ESTs to 34,276 reads. A total of 1,153 genes from the testis library had a blastx hit and GO annotation, including genes specific for meiosis, spermatogenesis, sex-differentiation, and transposable elements. Some of the identified meiosis genes function in chromosome pairing (scp2, scp3), recombination and DNA repair (dmc1, rad51, ccnb1ip1/hei10), and meiotic checkpoints (rad1, hormad1, dtl/cdt2). Gene expression analyses in different gametogenic stages in both sexual regions of the gonad of meiosis genes confirmed that the expression was specific or increased towards the maturing testis. Spermatogenesis genes included known testis-specific ones (kelch-10, shippo1, adad1), with some of these known to be associated to sterility. Sex differentiation genes included one of the most conserved genes at the bottom of the sex-determination cascade (dmrt1). Transcript from transposable elements, reverse transcriptase, and transposases in this library evidenced that transposition is an active process during spermatogenesis in N. subnodosus. In relation to the inactive library, we identified 833 transcripts with functional annotation related to activation of the transcription and translation machinery, as well as to germline control and maintenance.

Characterisation of human RING finger protein TRIM69, a novel testis E3 ubiquitin ligase and its subcellular localisation

The E3 ubiquitin ligase activity and subcellular localisation of human TRIM69 (hTRIM69) gene were studied. It was found that hTRIM69 mediated ubiquitination in an E2 conjugating enzyme selective fashion in vitro and an intact RING finger domain was indispensible for the process. Further evidences showed that hTRIM69 could mediate ubiquitination in vivo, which could be enhanced by a proteasome inhibitor. hTRIM69 was found to localise in both the cytoplasm and the nucleus in a speckled aggregating pattern, which also required an intact RING finger domain. Collectively, hTRIM69 is a novel E3 ubiquitin ligase identified from human testis and may function to ubiquitinate its particular substrates during spermatogenesis.

Isolation and analysis of genes mainly expressed in adult mouse heart using subtractive hybridization cDNA library

Subtractive hybridization cDNA library (SHL) is one of the powerful approaches for isolating differentially expressed genes. Using this technique between mouse heart and skeletal muscle (skm) tissues, we aimed to construct a cDNA-library that was specific to heart tissue and to identify the potential candidate genes that might be responsible for the development of cardiac diseases or related pathophysiological conditions. In the first step of the study, we created a cDNA-library between mouse heart and skm tissues. The homologies of the randomly selected 215 clones were analyzed and then classified by function. A total of 146 genes were analyzed for their expression profiles in the heart and skm tissues in published mouse microarray dataset. In the second step, we analyzed the expression patterns of the selected genes by Northern blot and RNA in situ hybridization (RISH). In Northern blot analyses, the expression levels of Myl3, Myl2, Mfn2, Dcn, Pdlim4, mt-Co3, mt-Co1, Atpase6 and Tsc22d1 genes were higher in heart than skm. For first time with this study, expression patterns of Pdlim4 and Tsc22d1 genes in mouse heart and skm were shown by RISH. In the last step, 43 genes in this library were identified to have relationships mostly with cardiac diseases and/or related phenotypes. This is the first study reporting differentially expressed genes in healthy mouse heart using SHL technique. This study confirms our hypothesis that tissue-specific genes are most likely to have a disease association, if they possess mutations.

A novel testis-specific GTPase serves as a link to proteasome biogenesis: functional characterization of RhoS/RSA-14-44 in spermatogenesis

We functionally characterized RhoS/RSA-14-44 as a new member of Rho GTPase subfamily in spermatogenesis, which provides a direct link between Rho family GTPase and the proteasome biogenesis.

Most Rho family GTPases serve as key molecular switches in a wide spectrum of biological processes. An increasing number of studies have expanded their roles to the spermatogenesis. Several members of Rho family have been confirmed to be essential for mammalian spermatogenesis, but the precise roles of this family in male reproduction have not been well studied yet. Here we report a surprising function of an atypical and testis-specific Rho GTPase, RSA-14-44 in spermatogenesis. Featured by unique structural and expressional patterns, RSA-14-44 is distinguished from three canonical members of Rho cluster. Thus, we define RSA-14-44 as a new member of Rho GTPases family and rename it RhoS (Rho in spermatogenic cells). RhoS associates with PSMB5, a catalytic subunit of the proteasome, in a series of stage-specific spermatogenic cells. More importantly, RhoS does not directly modulate the cellular proteasome activity, but participates in regulating the stability of “unincorporated” PSMB5 precursors. Meanwhile, our data demonstrate that the activation of RhoS is prerequisite for negatively regulating the stability of PSMB5 precursors. Therefore, our finding uncovers a direct and functional connection between the Rho GTPase family and the pathway of proteasome biogenesis and provide new clues for deciphering the secrets of spermatogenesis.

Immunolocalization of humanin in human sperm and testis

We have discovered, by immunocytochemistry and immunoelectronmicroscopy, that humanin (HN) is expressed in human ejaculated sperm and testis. In sperm, the HN immunolabeling pattern depends on sperm morphology; in particular, HN is mainly localized in the midpiece of sperm in semen samples with normal morphology and in cytoplasmic residues and entire tail in those with abnormal morphology. We also found HN in the cytoplasm and nucleus of spermatocytes and spermatids and in experimentally uncoiled chromatin of mature ejaculated sperm. Because it has been established that HN has antiapoptotic properties, it is reasonably hypothesized that HN may play an important role in preventing apoptosis in human sperm and testis. Thus, the examination of the HN localization in normal and abnormal sperm could be proposed as an auxiliary test to better define sperm quality.

Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 4: intercellular bridges, mitochondria, nuclear envelope, apoptosis, ubiquitination, membrane/voltage-gated channels, methylation/acetylation, and transcription factors

As germ cells divide and differentiate from spermatogonia to spermatozoa, they share a number of structural and functional features that are common to all generations of germ cells and these features are discussed herein. Germ cells are linked to one another by large intercellular bridges which serve to move molecules and even large organelles from the cytoplasm of one cell to another. Mitochondria take on different shapes and features and topographical arrangements to accommodate their specific needs during spermatogenesis. The nuclear envelope and pore complex also undergo extensive modifications concomitant with the development of germ cell generations. Apoptosis is an event that is normally triggered by germ cells and involves many proteins. It occurs to limit the germ cell pool and acts as a quality control mechanism. The ubiquitin pathway comprises enzymes that ubiquitinate as well as deubiquitinate target proteins and this pathway is present and functional in germ cells. Germ cells express many proteins involved in water balance and pH control as well as voltage-gated ion channel movement. In the nucleus, proteins undergo epigenetic modifications which include methylation, acetylation, and phosphorylation, with each of these modifications signaling changes in chromatin structure. Germ cells contain specialized transcription complexes that coordinate the differentiation program of spermatogenesis, and there are many male germ cell-specific differences in the components of this machinery. All of the above features of germ cells will be discussed along with the specific proteins/genes and abnormalities to fertility related to each topic.

Analysis of the budding yeast pH 4-7 proteome in meiosis

Meiosis, the developmental programme generating haploid gametes from diploid precursors, requires two cell divisions and many innovations. In budding yeast, a large number of genes are expressed exclusively during meiosis while others are repressed compared to vegetative growth. Microarray analysis has shown that gene expression during meiosis is highly regulated, and has been used to classify yeast genes according to meiotic temporal expression pattern. In this study, we have begun to investigate the kinetics of meiotic protein expression using a proteomics approach. 2-D DIGE was used to characterise the temporal protein expression patterns of the budding yeast pH 4-7 proteome in meiosis. More than 1400 meiotic protein spots were visualised and at least 63 spots were temporally regulated during meiosis in a statistically significant manner. Gel spots with significant expression changes were excised and 26 unique proteins were identified using LC-MS/MS. The identified proteins could be classified into functional categories and the genes encoding a number of these were previously shown to be involved in yeast sporulation and meiosis. This data set was used to assemble the first differential 2-D PAGE map of budding yeast meiosis, which can be accessed through a web server. This work represents one of the first quantitative proteomic analyses of meiosis in yeast and will provide a valuable resource for future investigations.

Application of laser-assisted microdissection for gene expression analysis of mammalian germ cells

Laser-assisted microdissection (LAM) is an important method to provide new significant insights into many embryological processes. To understand these processes, it is important to obtain specific populations of cells from complex tissue in an efficient and precise manner and to combine with many different molecular biological methods. During the last few years, the sophistication of the techniques of LAM has increased significantly and made the procedure easy to use. New micro-extraction protocols for DNA, RNA and proteins now allow broad downstream applications in the fields of genomics, transcriptomics and proteomics. In this review, we give a short overview of the application of LAM in combination with quantitative qPCR for the analysis of gene expression in mammalian germ cells.

Screening of genes involved in chromosome segregation during meiosis I: toward the identification of genes responsible for infertility in humans

Prophase I of male meiosis during early spermatogenesis involves dynamic chromosome segregation processes, including synapsis, meiotic recombination and cohesion. Genetic defects in the genes that participate in these processes consistently cause reproduction failure in mice. To identify candidate genes responsible for infertility in humans, we performed gene expression profiling of mouse spermatogenic cells undergoing meiotic prophase I. Cell fractions enriched in spermatogonia, leptotene/zygotene spermatocytes or pachytene spermatocytes from developing mouse testis were separately isolated by density gradient sedimentation and subjected to microarray analysis. A total of 726 genes were identified that were upregulated in leptotene/zygotene spermatocytes. To evaluate the screening efficiency for meiosis-specific genes, we randomly selected 12 genes from this gene set and characterized each gene product using reverse transcription (RT)-PCR of RNA from gonadal tissues, in situ hybridization on testicular tissue sections and subcellular localization analysis of the encoded protein. Four of the 12 genes were confirmed as genes expressed in meiotic stage and 2 of these 4 genes were novel, previously uncharacterized genes. Among the three confirmation methods that were used, RT-PCR appeared to be the most efficient method for further screening. These 726 candidates for human infertility genes might serve as a useful resource for next-generation sequencing combined with exon capture by microarray.

Opposing roles of insulin-like growth factor binding protein 3 and humanin in the regulation of testicular germ cell apoptosis

Modulating germ cell death and survival have significant therapeutic potential for male infertility and contraception. We have shown previously that IGF binding protein 3 (IGFBP3) gene expression is up-regulated in human testis when germ cell apoptosis is induced by intratesticular hormonal deprivation created by testosterone administration. Humanin (HN) is a binding partner of IGFBP3, and both are expressed in rat testes. We therefore hypothesized that IGFBP3, a proapoptotic factor, and HN, an antiapoptotic factor, are important regulators of male germ cell apoptosis. Whereas baseline apoptosis in the testis was equivalent between Igfbp3 knockout and wild-type mice, treatment with GnRH antagonist (GnRH-A) for 2 wk induced germ cell apoptosis in wild type, which was dramatically reduced in Igfbp3 knockout mice. To investigate the direct effects of IGFBP3 and HN on germ cell apoptosis, intratesticular administration of IGFBP3 for 5 d in rats induced a 4.2- and 3.8-fold increase in apoptosis at stages VII-VIII and XIV-I of the seminiferous epithelium cycle, respectively. GnRH-A treatment for 5 d increased apoptosis, mainly at stages VII-VIII. Addition of IGFBP3 to GnRH-A treatment enhanced apoptosis to 39.3-fold at stages VII-VIII, which was higher than either treatment alone. Intratesticular injection of HN significantly decreased GnRH-A-induced apoptosis at stages XIV-I but not stages VII-VIII. We conclude that IGFBP3 and HN play key roles in the coordinated regulation of testicular germ cell homeostasis. Perturbation of this interaction is important in enhancing or preventing germ cell death, providing new targets for future therapies.

Extra-mitochondrial localization and likely reproductive function of a female-transmitted cytochrome c oxidase subunit II protein

Our previous study documented a reproductive function for the male-transmitted mitochondrial DNA (mtDNA)-encoded cytochrome c oxidase subunit II (MCOX2) protein in a unionoid bivalve. Here, immunoblotting, immunohistochemistry and immunoelectron microscopy analyses demonstrate that the female-transmitted protein (FCOX2) is: (i) expressed in both male and female gonads; (ii) maximally expressed in ovaries just prior to the time of the annual fertilization event; (iii) displayed in the cytoplasm and more strongly in the plasma membrane (microvilli), vitelline matrix and vitelline envelope of mature ovarian eggs; and (iv) strongly localized to the vitelline matrix of some eggs just prior to fertilization. These findings represent evidence for the extra-mitochondrial localization of an mtDNA-encoded gene product and are consistent with multifunctionality for FCOX2 in eggs.

A novel testis protein, RSB-66, interacting with INCA1 (inhibitor of Cdk interacting with cyclin A1)

rsb-66 is a novel gene from a suppression subtracted hybridization (SSH) library of round spermatid-specific cDNAs against those of primary spermatocytes. It was found to be specifically expressed in round spermatids. To explore the function of RSB-66, a yeast two-hybrid system was used to screen for potential interacting partners in a human testis cDNA library. HSD45, also known as INCA1 (inhibitor of Cdk interacting with cyclin A1), was identified as one of the positive clones. The interaction between RSB-66 and INCA1 was demonstrated to occur by GST pull down and coimmunoprecipitation. Using immunofluorescence, RSB-66 was found to be specifically expressed in round spermatids, mainly in the cytoplasm. When being transfected into HeLa cells, RSB-66 and INCA1 were found to be co-localized principally in the cytoplasm. The alpha helix in the RSB-66 C terminal and two amino acid residues (tyr117 and his119) appear to be crucial for its function.

Application of laser-capture microdissection to analysis of gene expression in the testis

The isolation and molecular analysis of highly purified cell populations from complex, heterogeneous tissues has been a challenge for many years. Spermatogenesis in the testis is a particularly difficult process to study given the unique multiple cellular associations within the seminiferous epithelium, making the isolation of specific cell types difficult. Laser-capture microdissection (LCM) is a recently developed technique that enables the isolation of individual cell populations from complex tissues. This technology has enhanced our ability to directly examine gene expression in enriched testicular cell populations by routine methods of gene expression analysis, such as real-time RT-PCR, differential display, and gene microarrays. The application of LCM has however introduced methodological hurdles that have not been encountered with more conventional molecular analyses of whole tissue. In particular, tissue handling (i.e. fixation, storage, and staining), consumables (e.g. slide choice), staining reagents (conventional H&E vs. fluorescence), extraction methods, and downstream applications have all required re-optimisation to facilitate differential gene expression analysis using the small amounts of material obtained using LCM. This review will discuss three critical issues that are essential for successful procurement of cells from testicular tissue sections; tissue morphology, capture success, and maintenance of molecular integrity. The importance of these issues will be discussed with specific reference to the two most commonly used LCM systems; the Arcturus PixCell IIe and PALM systems. The rat testis will be used as a model, and emphasis will be placed on issues of tissue handling, processing, and staining methods, including the application of fluorescence techniques to assist in the identification of cells of interest for the purposes of mRNA expression analysis.

Reproductive function for a C-terminus extended, male-transmitted cytochrome c oxidase subunit II protein expressed in both spermatozoa and eggs

Our previous study documented expression of a male-transmitted cytochrome c oxidase subunit II protein (MCOX2), with a C-terminus extension (MCOX2e), in unionoidean bivalve testes and sperm mitochondria. Here, we present evidence demonstrating that MCOX2 is seasonally expressed in testis, with a peak shortly before fertilization that is independent of sperm density. MCOX2 is localized to the inner and outer sperm mitochondrial membranes and the MCOX2 antibody's epitope is conserved across >65 million years of evolution. We also demonstrate the presence of male-transmitted mtDNA and season-specific MCOX2 spatial variation in ovaries. We hypothesize that MCOX2 plays a role in reproduction through gamete maturation, fertilization and/or embryogenesis.

Crypticity and functional distribution of the membrane associated α-L-fucosidase of human sperm

Two distinctive isoforms of the enzyme alpha-L-fucosidase are found within human semen in substantial amounts, suggesting specialized functions during reproduction. The membrane-associated isozyme of human sperm cells was previously characterized biochemically, and here we report on its subcellular localization. Intact, detergent permeabilized, capacitated, and acrosome-reacted sperm were investigated using antifucosidase immunofluorescence, binding of the fluorescent fucosylated glycoconjugate RITC-BSA-fucose (RBF), and enzyme activity in the presence and absence of selected inhibitors. Both immunolocalization and RBF binding show that fucosidase is broadly distributed over the membrane systems of human sperm, but is relatively enriched within the equatorial segment. Upon detergent treatment or induction of acrosome reaction (AR), a portion of enzyme activity is recoverable in the supernatant, presumably associated with released remnants of the outer acrosomal membrane. Surprisingly, cell-bound enzyme activity increases sharply following permeabilization of intact sperm, representing cryptic fucosidase that is relatively stable and corresponds with strong fluorescence in the equatorial segment and other sperm membranes. These observations support the notion that the fucosidase has a role in the intimate species signature interactions between sperm and oocyte.

Anti-apoptotic factor humanin is expressed in the testis and prevents cell-death in leydig cells during the first wave of spermatogenesis

Humanin (HN) is a 24 amino acids peptide with potent neuro-survival properties that protects against damage associated with Alzheimer's disease. In the present report, we have demonstrated by immunohistochemical analysis and Western blotting the pattern of expression of rat humanin (HNr) in the testis of 10- to 60-day-old rats. The Leydig cells of 10- and 40- day-old rats expressed this peptide at high levels; and in the testis of 60-day-old rats the expression of HNr expanded to include Leydig, endothelial, peritubular and germ cells. As monitored by Western blotting, HNr was released into the medium of cultures of Leydig cells isolated from 10-, 40-, and 60-days-old rats. HNr stimulated the incorporation of [(3)H]TdR into DNA of Leydig cells from 10-days-old rats, in a manner that indicated promotion of cell survival rather than an increase in the rate of cell multiplication. This peptide also enhanced steroidogenesis by cultured Leydig cells from 10- to 40-day-old rats both alone and synergistically with IGF-I. The expression of HNr in cultured Leydig cells increased in response to GH and IGF-I. In summary, we demonstrated here that HNr was expressed at all stages of maturation in the rat testis. This peptide promoted the survival of Leydig cells in culture and interacted with IGF-I to stimulate DNA synthesis and steroidogenesis. We propose that HNr is a novel testicular anti-apoptotic factor.

Development and evaluation of a micro- and nanoscale proteomic sample preparation method

Challenges associated with the efficient and effective preparation of micro- and nanoscale (micro- and nanogram) clinical specimens for proteomic applications include the unmitigated sample losses that occur during the processing steps. Herein, we describe a simple "single-tube" preparation protocol appropriate for small proteomic samples using the organic cosolvent, trifluoroethanol (TFE) that circumvents the loss of sample by facilitating both protein extraction and protein denaturation without requiring a separate cleanup step. The performance of the TFE-based method was initially evaluated by comparisons to traditional detergent-based methods on relatively large scale sample processing using human breast cancer cells and mouse brain tissue. The results demonstrated that the TFE-based protocol provided comparable results to the traditional detergent-based protocols for larger, conventionally sized proteomic samples (>100 microg protein content), based on both sample recovery and numbers of peptide/protein identifications. The effectiveness of this protocol for micro- and nanoscale sample processing was then evaluated for the extraction of proteins/peptides and shown effective for small mouse brain tissue samples (approximately 30 microg total protein content) and also for samples of approximately 5000 MCF-7 human breast cancer cells (approximately 500 ng total protein content), where the detergent-based methods were ineffective due to losses during cleanup and transfer steps.

A cDNA macroarray approach to parasite-induced gene expression changes in a songbird host: genetic response of house finches to experimental infection by Mycoplasma gallisepticum

In 1994, the bacterial parasite Mycoplasma gallisepticum expanded its host range and swept through populations of a novel host--eastern US populations of the house finch (Carpodacus mexicanus). This epizootic caused a dramatic decline in finch population numbers, has been shown to have caused strong selection on house finch morphology, and presumably caused evolutionary change at the molecular level as finches evolved enhanced resistance. As a first step toward identifying finch genes that respond to infection by Mycoplasma and which may have experienced natural selection by this parasite, we used suppression subtractive hybridization (SSH) and cDNA macroarray approaches to identify differentially expressed genes regulated by the Mycoplasma parasite. Two subtractive cDNA libraries consisting of 16,512 clones were developed from spleen using an experimentally uninfected bird as the 'tester' and an infected bird as 'driver', and vice versa. Two hundred and twenty cDNA clones corresponding 34 genes with known vertebrate homologues and a large number of novel transcripts were found to be qualitatively up- or down-regulated genes by high-density filter hybridization. These gene expression changes were further confirmed by a high throughout reverse Northern blot approach and in specific cases by targeted Northern analysis. blast searches show that heat shock protein (HSP) 90, MHC II-associated invariant chain (CD74), T-cell immunoglobulin mucin 1 (TIM1), as well as numerous novel expressed genes not found in the databases were up- or down-regulated by the host in response to this parasite. Our results and macroarray resources provide a foundation for molecular co-evolutionary studies of the Mycoplasma parasite and its recently colonized avian host.