Interstrain differences in testicular responses to hCG: effects of a female exposition

It is known that among many animal species, including laboratory mice, a short-time exposition to a female causes activation of the pituitary-testicular axis in males, which then rapidly decreases. Effects of a prolonged female exposition on the testicular testosterone output in response to hCG injections were investigated in adult males of two inbred mice strains CBA/Lac and PT. The males of both genotypes kept with females for 5 days were injected subcutaneously with 10 IU of hCG 120 minutes before decapitation. Males of the same genotype and similar age keeping alone were served as control. The serum testosterone concentration and its testicular content were measured with immune-enzyme assay. It has been shown that the hCG increased the testosterone concentration and its testicular content in control males of both strains, but the testosterone output was expressed more significantly in PT males in comparison with CBA/Lac. The prolonged exposition of a female itself did not influence the testosterone output in males of both strains. However, it increased significantly the testicular response to hCG in PT strain. The data obtained suggest that a long-term exposition of a female could reinforce the testicular reactivity to hCG in genotype-dependent manner.     

Overt and covert competition in a promiscuous mammal: the importance of weaponry and testes size to male reproductive success

Male contests for access to receptive females are thought to have selected for the larger male body size and conspicuous weaponry frequently observed in mammalian species. However, when females copulate with multiple males within an oestrus, male reproductive success is a function of both pre- and postcopulatory strategies. The relative importance of these overt and covert forms of sexual competition has rarely been assessed in wild populations. The Soay sheep mating system is characterized by male contests for mating opportunities and high female promiscuity. We find that greater horn length, body size and good condition each independently influence a male's ability to monopolize receptive females. For males with large horns at least, this behavioural success translates into greater siring success. Consistent with sperm-competition theory, we also find that larger testes are independently associated with both higher copulation rates and increased siring success. This advantage of larger testes emerges, and strengthens, as the number of oestrous females increases, as dominant males can no longer control access to them all. Our results thus provide direct quantitative evidence that male reproductive success in wild populations of mammals is dependent upon the relative magnitude of both overt contest competition and covert sperm competition.     

Kinetic and autoradiographic studies on binding of hCG to the testicular LH receptors of neonatal rats

The properties of hCG binding to LH receptors of the neonatal (5-day-old) rat testis were analysed and compared with those of the adult testis. The equilibrium association constants (Ka) of hCG-binding were similar at both ages, 2-4 X 10(10) M-1. In contrast, kinetic binding studies revealed that the association and dissociation rate constants of hCG binding were more rapid in the neonatal testis. Likewise, it was observed that the progression from loose (easily dissociable) to tight (non-dissociable) binding was less complete in the young than in the adult testis. Autoradiography of 125I-labelled hCG binding to interstitial cell suspensions at the two ages showed that the gonadotrophin binding per Leydig cell was about 50% lower in the neonatal testis. Conversely, since the surface area of adult Leydig cells was about 4-fold larger, the receptor density appeared to be higher in the neonatal Leydig cells. The rapid recovery of LH receptors after hCG stimulation, typical of the neonatal cells, was due to rapid replenishment of binding in the cells initially occupied by the injected hormone, rather than to an hCG-induced increase of Leydig cell number. Finally, in-vivo experiments with cycloheximide revealed that the rapid recovery of LH receptors was dependent on protein synthesis. These differences in the kinetics of neonatal testicular LH receptor turnover may be involved in the unique functional features of the fetal-neonatal growth phase of rat testicular Leydig cells.     

Expression of intermediate filaments and other special markers by testicular germ cell tumors. With reference to embryogenesis.

Distribution of intermediate filament proteins (IFs) and several special markers was studied in 39 testicular germ cell tumors and 8 embryos and foetuses. The similarity and difference between development of germ cell tumor and embryogenesis were immunohistochemically investigated. Seminoma and embryonal carcinoma, as tumoral counterparts of undifferentiated germ cells, were characterized by little IF expression. This study revealed that the maturing and differentiating process in germ cell tumor is different from normal embryonal development and the tumor cells showed leaping maturing steps in tumorigenesis. Immunostaining for IFs helped to discover the further differentiation occurring in embryonal carcinoma and to demonstrate heterogeneous elements in non-seminoma germ cell tumors, which sometimes might not be apparent by light microscopical observation of H&E staining section. According to the findings, two patterns in mixed germ cell tumors are suggested; i.e., combined and diffuse types. The mechanism of tumorigenesis of the two types is supposed to be different. Clinically, the prognosis of most patients with testicular germ cell tumor is fairly good because of the improved chemotherapies that are dependent on histological diagnosis.     

The nucleotide sequence of a small cryptic plasmid found in Staphylococcus aureus and its relationship to other plasmids

The nucleotide sequence of a small (1273 bp) plasmid (pOX1000) of Staphylococcus aureus has been determined and compared with similar plasmids. The sequence includes a single open reading frame; two large palindromes and a 22 bp palindrome that is contiguously repeated three times upstream of the open reading frame. Composite plasmids of pE194ts and pOX1000 were constructed with pUC18 separately inserted into five different sites on pOX1000 and used to analyse the replication functions of the cryptic plasmid.     

Division of constricted and urethane-treated sand dollar eggs: a test of the polar stimulation hypothesis

In spherical cells with a central mitotic apparatus, the centers of the asters are closer to the poles than to the equator. This circumstance is basic to several hypothetical explanations of the way in which the mitotic apparatus establishes the division mechanism. This investigation was designed to determine whether that geometrical relationship is necessary for division. Fertilized, mechanically denuded sand dollar eggs were inserted into glass loops, which reduced the diameter in the constriction plane from the normal 142 to 78-80 microns and partly constricted the cell into equal parts. The mitotic apparatus straddled the constriction, and its length was not significantly changed. The manipulation increased the distance from the astral centers to the poles and decreased the distance from the astral centers to the equator to a degree that reversed the normal distance relations. These cells divided normally. Ethyl urethane (0.06 M) reduces the size of the mitotic apparatus and blocks cleavage in spherical cells. When treated cells are confined in 80-microns i.d. capillaries, they divide. Treated cells also divide when they are constricted by an 80-microns i.d. glass loop if the mitotic apparatus straddles the constriction. An equal degree of constriction in the subfurrow and subpolar areas did not reverse the effect of urethane. The results demonstrate that cleavage does not depend on the normal distance relation between the mitotic apparatus and the poles, and that the urethane effect can be remedied only by reducing the distance between the mitotic apparatus and the equatorial surface. Both findings are inconsistent with the polar stimulation hypothesis.     

Sheep testicular gonadotropin binding sites: characterization and changes with surgical shortening of the scrotum

Gonadotropin receptors in previously frozen (-70 degrees C) sheep testicular tissue were characterized, and methods of assessment of receptor binding activity were established and applied to an investigation of testicular function in the short scrotum ram. Binding of 125I-labelled ovine luteinizing hormone (125I-oLH) and 125I-labelled ovine follicle-stimulating hormone (125I-oFSH) to testicular membranes was highly specific and saturable. Uptake of labelled gonadotropins was proportional to the amount of membrane protein, with 125I-oFSH showing greater specific binding. Initial association of 125I-oLH with binding sites was comparable at 4, 25, and 34 degrees C; with prolonged incubation, maximal binding occurred at 4 degrees C. Equilibrium was achieved in 8 h at 34 degrees C and in 16 h at 25 and 4 degrees C. In contrast, the temperature-dependent association of LH with rat testicular membranes was greater at 25 than at 4 degrees C. The rate of association of 125I-oFSH to binding sites was proportional to incubation temperature, with equilibrium being achieved in 2 h at 34 degrees C and in 16 h at 25 degrees C; binding at 4 degrees C; was slow and still increasing by 48 h. Binding of radioactive and nonradioactive oLH and oFSH was hormone specific and increased in a dose-dependent manner until saturation occurred. Shortening the scrotum of adult rams led to reductions (p less than 0.05) in testicular weight (60%) and in the number of LH (55%) and FSH (90%) binding sites per testis, with no apparent change in serum testosterone concentration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Tumefactive multiple sclerosis requiring emergent biopsy and histological investigation to confirm the diagnosis: a case report

Introduction

Tumefactive multiple sclerosis is a demyelinating disease that demonstrates tumor-like features on magnetic resonance imaging. Although diagnostic challenges without biopsy have been tried by employing radiological studies and cerebrospinal fluid examinations, histological investigation is still necessary for certain diagnosis in some complicated cases.

Case presentation

A 37-year-old Asian man complaining of mild left leg motor weakness visited our clinic. Magnetic resonance imaging demonstrated high-signal lesions in bilateral occipital forceps majors, the left caudate head, and the left semicentral ovale on fluid-attenuated inversion recovery and T2-weighted imaging, and these lesions were enhanced by gadolinium-dimeglumin. Tumefactive multiple sclerosis was suspected because the enhancement indistinctly extended along the corpus callosum on magnetic resonance imaging and scintigraphy showed a low malignancy of the lesions. But oligoclonal bands were not detected in cerebrospinal fluid. In a few days, his symptoms fulminantly deteriorated with mental confusion and left hemiparesis, and steroid pulse therapy was performed. In spite of the treatment, follow-up magnetic resonance imaging showed enlargement of the lesions. Therefore, emergent biopsy was performed and finally led to the diagnosis of demyelinating disease. The enhanced lesion on magnetic resonance imaging disappeared after one month of prednisolone treatment, but mild disorientation and left hemiparesis remained as sequelae.

Conclusions

Fulminant aggravation of the disease can cause irreversible neurological deficits. Thus, an early decision to perform a biopsy is necessary for exact diagnosis and appropriate treatment if radiological studies and cerebrospinal fluid examinations cannot rule out the possibility of brain tumors.     

Bioconversion of the androgen precursors by pre- and post-pubertal rat testes with special reference to local irradiation and gonadotropin stimulation

Pubertal changes in the testicular steroid enzyme activities, responsible for the androgen production, were studied in rats in relation to the effects of testicular irradiation, followed by gonadotropin stimulation and cyproterone suppression. Five groups of pro-pubertal and adult rats were used in this study. The $\text{in vitro}$ bioconversion from progesterone-4-14C and 17-hydroxyprogesterone-44C to testosterone, androstenedione, androstanediol, dihydrotestosterone and androsterone, demonstrated the effect of age in all cases of drug response investigations. The sexually immature animals in the control group had higher levels of androstenedione than testosterone, in contrast to the findings in the adults. With irradiation, androgen biosynthesis was suppressed in both age groups, which did not recover, under gonadotropin stimulation, in spite of the generation of new cells caused by the treatment. The irradiated adult testes demonstrated ‘pre-pubertal’ type bioconversion by catabolizing the substrates more towards 5α-reduced androgens, like androstanediol (5α-androstane-3α 17β-diol) and androsterone. With cyproterone the 17α-hydroxylase activities were found to be diminished.     

L-cell growth stimulation by a beta-casein peptide: the importance of its phosphorylation site for activity.

L-cell proliferation was markedly enhanced by addition to the medium of a synthetic peptide corresponding to residues 1-18 of human beta-casein. Experiments using several synthetic peptides of decreasing length demonstrated that L-S-S-S-E-E (residues 7-12), a major phosphorylation site in beta-casein, appeared to be important for the activity. The phosphorylated beta-casein peptide showed no activity. Recent findings have demonstrated that a similar sequence, S-E-E-E or S-D-D-E, is commonly present in many oncoproteins derived from nuclear oncogenes such as myc, myb and E1A, and plays an important role in transformation functions. The beta-casein peptide may affect mammalian cell proliferation through a modification of of the oncoprotein functions.     

Assessing the scale-specific importance of niches and other spatial processes on beta diversity: a case study from a temperate forest

Niche processes and other spatial processes, such as dispersal, may simultaneously control beta diversity, yet their relative importance may shift across spatial and temporal scales. Although disentangling the relative importance of these processes has been a continuing methodological challenge, recent developments in multi-scale spatial and temporal modeling can now help ecologists estimate their scale-specific contributions. Here we present a statistical approach to (1) detect the presence of a space–time interaction on community composition and (2) estimate the scale-specific importance of environmental and spatial factors on beta diversity. To illustrate the applicability of this approach, we use a case study from a temperate forest understory where tree seedling abundances were monitored during a 9-year period at 40 permanent plots. We found no significant space–time interaction on tree seedling composition, which means that the spatial abundance patterns did not vary over the study period. However, for a given year the relative importance of niche processes and other spatial processes was found to be scale-specific. Tree seedling abundances were primarily controlled by a broad-scale environmental gradient, but within the confines of this gradient the finer scale patchiness was largely due to other spatial processes. This case study illustrates that these two sets of processes are not mutually exclusive and can affect abundance patterns in a scale-dependent manner. More importantly, the use of our methodology for future empirical studies should help in the merging of niche and neutral perspectives on beta diversity, an obvious next step for community ecology. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Nitrogen inputs to a marine embayment: the importance of groundwater

We examined the importance of nitrogen inputs from groundwater and runoff in a small coastal marine cove on Cape Cod, MA, USA. We evaluated groundwater inputs by three different methods: a water budget, assuming discharge equals recharge; direct measurements of discharge using bell jars; and a budget of water and salt at the mouth of the Cove over several tidal cycles. The lowest estimates were obtained by using a water budget and the highest estimates were obtained using a budget of water and salt at the Cove mouth. Overall there was more than a five fold difference in the freshwater inputs calculated by using these methods. Nitrogen in groundwater appears to be largely derived from on site septic systems. Average nitrate concentrations were highest in the region where building density was greatest. Nitrate in groundwater appeared to behave conservatively in sandy sediments where groundwater flow rates were high (> 11/m²/h), indicating that denitrification was not substantially reducing external nitrogen loading to the Cove. Nitrogen inputs from groundwater were approximately 300 mmol-N/m³/y of Cove water. Road runoff contributed an additional 60 mmol/m³/y. Total nitrogen inputs from groundwater and road runoff to this cove were similar in magnitude to river dominated estuaries in urbanized areas in the United States.     

Deme formation in scale insects: a test with the pinyon needle scale and a review of other evidence

ABSTRACT. 1. Deme formation is the transformation of a generalist population into one which is adapted to its local conditions. This adaptation has been inferred from many things but should be inferred from higher survival or fecundity of scale insects on their natal tree compared to that of immigrant scales on the same tree.
2. Transfers of the scale insect Matsucoccus acalyptus Herbert within and between infested host trees ( Pinus monophylla (Torr. & Frem.) resulted in significant differences in scale survivorship among recipient trees. Survival on individual trees was correlated across years, indicating stable differences in tree susceptibility to scale.
3. A significant natal tree colonized tree interaction was observed for late stage scale survival in one experiment but the interaction was not caused by superior survivorship of scales transferred back to the natal tree. Hence, we found no evidence of deme formation in M.acalyptus.
4. Previous studies have concluded that deme formation occurs in the black pineleaf scale based on a significant natal tree by colonized tree interaction in scale survival. We question this conclusion because the experimental design employed did not include transfers back onto the natal tree. Other indirect evidence for deme formation in scale insects is critically discussed.     

Transport of threonine and tryptophan by rat brain slices: relation to other amino acids at concentrations found in plasma

Threonine content of brain decreases in young rats fed a threonine-limiting, low protein diet containing a supplement of small neutral amino acids (serine, glycine and alanine), which are competitors of threonine transport in other systems (Tews et al., 1977). Threonine transport by brain slices was inhibited more by a complex amino acid mixture resembling plasma from rats fed the small neutral amino acid supplement than by mixtures resembling plasma from control rats or from rats fed a supplement of large neutral amino acids. Greater inhibition was seen with mixtures containing only the small neutral amino acids than with mixtures containing only large neutral amino acids. On an equimolar basis, serine and alanine were the most inhibitory; large neutrals were moderately so; and glycine and lysine were without effect. Threonine transport was also strongly inhibited by α-amino-n-butyric acid and homoserine, less so by α-aminoisobutyric acid, and not at all by GABA. The complex amino acid mixtures strongly inhibited α-aminoisobutyric acid transport by brain or liver slices but, in contrast to effects in brain, the extent of the inhibition in liver was not much affected by altering the composition of the mixture. Tryptophan accumulation by brain slices was effectively inhibited by other large neutral amino acids in physiologically occurring concentrations. Threonine, or a mixture of serine, glycine and alanine only slightly inhibited tryptophan uptake; basic amino acids were without effect and histidine stimulated tryptophan transport slightly. These results support the conclusion that a diet-induced decrease in the concentration in brain of a specific amino acid may be related to increased inhibition of its transport into brain by increases in the concentrations of transport-related, plasma amino acids.     

A test of mink microsatellite markers in the ferret: amplification and sequence comparisons

Short tandem repeats are a source of highly polymorphic markers in mammalian genomes. Genetic variation at these hypervariable loci is extensively used for linkage analysis and to identify individuals, and is very useful for interpopulation and interspecies studies. Fifty-nine microsatellite markers from American mink were tested in the ferret, under the same conditions as for the mink. Of the 59, 43 of them (73.5%) amplified a ferret sequence; 5 amplification products differed in size from the respective mink sequences. Ten amplified fragments from ferret were sequenced. The sequences that were identical in size to those from mink displayed a high degree of conservation, with some differences at the repeat motif sites. These results could aid cross-utilization of markers between these two species.