Isolation and Characterization of Autosomal Male Sterile Mutants in \u3cem\u3eDrosophila melanogaster\u3c/em\u3e

In order to study the genetic control of spermiogenesis, recessive, male-sterile, autosomal mutants of Drosophila melanogaster were induced with ethyl methanesulfonate. A total of 31 mutants were recovered, 15 of which were located on the second chromosome and 16 on the third chromosome. Eight second- and 6 third-chromosome mutants demonstrating sterility in all homozygous males were used for further analysis. Complementation tests showed that 2 of the 8 second chromosome mutants (and none of the 6 third chromosome mutants) were noncomplementing, indicating that two of the mutants produced were alleles of the same locus. Mapping of the second chromosome mutants indicated a clustering near the heterochromatin in the left arm. In 2 of the mutants, spermiogenesis was studied with the light and electron microscopes. Mutant C2-3 has an anomaly associated with cytokinesis accompanying meiosis. The primary spermatocyte undergoes nuclear division, but a failure of cytokinesis leaves 4 spermatids to develop within a common cytoplasm. The mitochondria fuse, usually forming a single large nebenkern, which then divides into two approximately equal parts, as normal nebenkern does. In the mutant these two mitochodrial derivatives usually undergo further division generally giving rise to 8 or fewer mitochondrial derivatives. Multiple paracrystalline bodies are often observed in the primary mitochondrial derivatives. Up to 4 paracrystalline bodies may form, one at each contact point between the membranes of the primary mitochondrial derivative and the membranes around the four axonemes contained in the common cytoplasmic unit. The groups of 4 spermatids almost complete maturation before the bundles degenerate. Mutant C2-10 is characterized by two anomalies: (1) disruption of the axonemal complex, and (2) formation of multiple paracrystalline bodies within the primary mitochondrial derivative. This mutant undergoes limited elongation with some variation between bundles of maturing spermatids. Axonemal complexes apparently complete differentiation even through disrupted and scattered in the cytoplasm. Mitochondrial derivatives are often very large and contain several paracrystalline bodies. The paracrystalline bodies form within the primary mitochondrial derivatives at contact points between the membranes of the derivative and the cytoplasmic membranes. Abnormally large numbers of microtubules are observed within spermatids containing large mitochondrial derivatives and appear to be rather uniformly distributed around the derivatives. The large derivative size is presumed to be due to failure of normal elongation. Spermatids degenerate rather late in the maturation process

The SAMR Model as a Framework for Evaluating mLearning

As mobile devices become more prominent in the lives of students, the use of mobile devices has the potential to transform learning. Mobile learning, or mLearning, is defined as learning that is personalized, situated, and connected through the use of a mobile device. As mLearning activities are developed, there is a need for a framework within which mLearning activities can be evaluated. The SAMR Model (Puentadura, 2012) provides such a framework. This paper reviews recent literature on mLearning and provides examples of activities that fall within each of the four classifications of the SAMR Model: substitution, augmentation, modification, and redefinition

Development of an in vitro test system for assessment of male, reproductive toxicity.

yesThere is a need for improved reproductive toxicology assays that do not require large numbers of animals but are sensitive and informative. Therefore, Staput velocity-sedimentation separation followed by culture of specific mouse testicular cells was used as such a system. The specificity of separation was assessed using immunocytochemistry to identify spermatids, spermatocytes and spermatogonia. The efficacy of the system to detect toxicity was then evaluated by analysing the effects of hydrogen peroxide (H2O2) by the terminal uridine-deoxynucleotide end-labelling (TUNEL) assay to show the rate of apoptosis induced among the different types of germ cells. We found that 2 h of treatment at both 1 and 10 μM induced increases of over ∼10-fold in the percentage of apoptotic cells (p ≤ 0.001), confirming that testicular germ cells are prone to apoptosis at very low concentrations of H2O2. It was also demonstrated for the first time for this compound that spermatogonia are significantly more susceptible than spermatocytes, which are more affected than spermatids. This reflects the proportion of actively dividing cells in these cell types, suggesting a mechanism for the differential sensitivity. The approach should thus form the basis of a useful test system for reproductive and genetic toxicology in the future

Testosterone therapy in men with Parkinson disease : results of the TEST-PD study

Background: Testosterone deficiency has been reported in patients with Parkinson disease (PD), Alzheimer disease, and Huntington disease. It is not known whether testosterone therapy (TT) in men with borderline hypogonadism and neurodegenerative diseases will be of substantial benefit. Previously, we reported that testosterone deficiency is more common in patients with PD compared with age-matched control subjects, and we also reported in 2 small open-label studies that some nonmotor symptoms responded favorably to TT. Objective To define the effects of TT on nonmotor and motor symptoms in men with PD and probable testosterone deficiency. Design: Double-masked, placebo-controlled, parallel-group, single-center trial. Patients: Two experimental groups: patients with PD who were receiving either TT or placebo. Interventions: Participants received either the study drug by intramuscular injection (200 mg/mL of testosterone enanthate every 2 weeks for 8 weeks) or placebo (isotonic sodium chloride solution injections). In patients in each group, the testosterone serum concentration was obtained at each study visit. During 2 study visits, testosterone levels were blindly evaluated and the intramuscular testosterone dose was increased by 200 mg/mL if the free testosterone value failed to double from the baseline value. Main Outcome Measures: The primary outcome variable was the St Louis Testosterone Deficiency Questionnaire, and secondary outcome measures included measures of mood, cognition, fatigue, motor function, and frequency of adverse events. At the end of the double-blind phase, all patients were offered open-label TT and were followed up after 3 and 6 months. Results: Fifteen patients in the placebo group (mean age, 69.9 years), receiving a mean total levodopa equivalent dose of 924 mg/d, had a baseline free testosterone level of 47.91 pg/mL, compared with 15 patients in the TT group (mean age, 66.7 years), receiving an average total levodopa equivalent dose of 734 mg/d, who had a baseline free testosterone level of 63.49 pg/mL. Testosterone was generally well tolerated. More subjects in the TT group experienced lower extremity edema (40% vs 20%). In 2 patients, 1 in each group, prostate-specific antigen levels were elevated from baseline. The improvement in the TT group compared with the placebo group (1.7 vs 1.1) on the St Louis Testosterone Deficiency Scale was not statistically significant. In addition, there were no significant differences in motor and nonmotor features of PD between the 2 groups, although a few subscales showed improvements (Hopkins Verbal Learning Test, P<.04; and Backward Visual Span subtrial, P<.03). However, long-term open-label TT resulted in delayed but sustained improvement in subjects in the TT group who continued to receive treatment (n = 6) compared with subjects in the placebo group who elected not to receive TT (n = 3). Conclusions: Testosterone therapy was generally well tolerated in elderly men with PD and probable testosterone deficiency. While there was no significant difference in the motor and nonmotor scales between the TT and placebo groups at the end of 8 weeks compared with baseline, this may be due to several study limitations, including small sample size, a strong placebo effect with intramuscular therapy, and short follow-up that did not allow measurement of delayed effects of TT in some subjects. Until more definitive studies are reported, practitioners should be particularly cautious in treatment of low testosterone concentrations in men with PD and borderline testosterone deficiency, and careful consideration should be given to the risks vs the benefits of TT

Acid Glycohydrolases in Rat Spermatocytes, Spermatids and Spermatozoa: Enzyme Activities, Biosynthesis and Immunolocalization

Mammalian sperm acrosome contains several glycohydrolases thought to aid in the dispersion and digestion of vestments surrounding the egg. In this study, we have used multiple approaches to examine the origin of acrosome-associated glycohdyrdolases. Mixed spermatogenic cells, prepared from rat testis, were separated by unit gravity sedimentation. The purified germ cells (spermatocytes [SP], round spermatids [RS], and elongated/condensed spermatids [E/CS]) contained several glycohydrolase activities. Metabolic labeling in the cell culture, immunoprecipitation, and autoradiographic approaches revealed that β-D-galactosidase was synthesized in SP and RS in 88/90 kDa forms which undergo processing in a cell-specific manner. Immunohistochemical approaches demonstrated that the enzyme was localized in Golgi membranes/vesicles, and lysosome-like structures in SP and RS, and forming/formed acrosome of E/CS

Ultra-Fast and Optimized Method for the Preparation of Rodent Testicular Cells for Flow Cytometric Analysis

Homogeneity of cell populations is a prerequisite for the analysis of biochemical and molecular events during male gamete differentiation. Given the complex organization of the mammalian testicular tissue, various methods have been used to obtain enriched or purified cell populations, including flow cell sorting. Current protocols are usually time-consuming and may imply loss of short-lived RNAs, which is undesirable for expression profiling. We describe an optimized method to speed up the preparation of suitable testicular cell suspensions for cytometric analysis of different spermatogenic stages from rodents. The procedure takes only 15 min including testis dissection, tissue cutting, and processing through the Medimachine System (Becton Dickinson). This method could be a substitute for the more tedious and time-consuming cell preparation techniques currently in use

Haploid accumulation and translational control of phosphoglycerate kinase-2 messenger RNA during mouse spermatogenesis

The intracellular location of the mRNA for the testis-specific isozyme of phosphoglycerate kinase-2 (PGK-2) has been determined for two spermatogenic cell types. The mRNA activity for PGK-2 from the polysomal and nonpolysomal fractions of pachytene primary spermatocytes or round spermatids has been assayed by cell-free translation with the polypeptide products monitored by immunoprecipitation, followed by one-dimensional or two-dimensional electrophoresis and fluorography. The results reveal that the majority of PGK-2 mRNA activity of round spermatids was present in the polysomal fraction while the relatively less abundant PGK-2 mRNA of pachytene primary spermatocytes was present in the nonpolysomal fraction. No PGK-2 mRNA activity was observed in the cytoplasmic RNA from primitive type A spermatogonia or prepubertal Sertoli cells. These data indicate that mature PGK-2 mRNA first appears in the cytoplasm of spermatogenic cells during the prophase of meiosis and increases in amount after meiosis. Although mature PGK-2 mRNA is present in meiotic cells it is not actively translated until after meiosis has been completed. Thus, mRNA accumulation and translational mechanisms are involved in the control of phosphoglycerate kinase-2 synthesis during spermatogenesis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25153/1/0000589.pd

An Essential Role for Katanin p80 and Microtubule Severing in Male Gamete Production

Katanin is an evolutionarily conserved microtubule-severing complex implicated in multiple aspects of microtubule dynamics. Katanin consists of a p60 severing enzyme and a p80 regulatory subunit. The p80 subunit is thought to regulate complex targeting and severing activity, but its precise role remains elusive. In lower-order species, the katanin complex has been shown to modulate mitotic and female meiotic spindle dynamics and flagella development. The in vivo function of katanin p80 in mammals is unknown. Here we show that katanin p80 is essential for male fertility. Specifically, through an analysis of a mouse loss-of-function allele (the Taily line), we demonstrate that katanin p80, most likely in association with p60, has an essential role in male meiotic spindle assembly and dissolution and the removal of midbody microtubules and, thus, cytokinesis. Katanin p80 also controls the formation, function, and dissolution of a microtubule structure intimately involved in defining sperm head shaping and sperm tail formation, the manchette, and plays a role in the formation of axoneme microtubules. Perturbed katanin p80 function, as evidenced in the Taily mouse, results in male sterility characterized by decreased sperm production, sperm with abnormal head shape, and a virtual absence of progressive motility. Collectively these data demonstrate that katanin p80 serves an essential and evolutionarily conserved role in several aspects of male germ cell development

Acoustic emission weld monitoring of nuclear components

Acoustic emission monitoring augments other nondestructive testing methods and is sometimes applicable when other tests cannot be applied. This is, in part, due to the high sensitivity of acoustic emission monitoring. Acoustic emission monitoring is only sensitive to active flaw-growth, however, and will not detect a flaw in equilibrium. This paper describes the application of acoustic emission monitoring to nuclear reactor fuel pin end closure welds and other weldments of the reactor piping