The ultrastructural organization of the mature spermatozoon of Luidia clathrata (Say) (Echinodermata: Asteroidea)

The sperm of Luidia clathrata are morphologically typical of asteroid sperm. The head is spherical and contains the nucleus and acrosomal complex. The nucleus has an anterior indentation in which rests the acrosomal complex. There is no evidence of a centriolar fossa along the posterior border of the nucleus. The acrosome is a cup-shaped structure containing a less electron dense central region. The periacrosomal material is homogeneous in nature, and the subacrosomal specialization of the periacrosomal materials appear as bands of varying electron density. The middle piece is an annular band of mitochondria which surrounds the proximal and distal centrioles. The centrioles exhibit the typical nine triplet arrangement. Both the centrioles and the axoneme project to one side of the middle piece region. Associated with the distal centriole is an elaborate pericentriolar process.     

Ultrastructural evidence for Sertoli-like cells in the testis of the asteroid,Luidia clathrata (Say) (Echinodermata: Platyasterida)

Non-germinal cells arise adjacent to the basal lamina and extend between the numerous germinal celli. Nuclei of these non-germinal cells may be positioned near the basal lamina or more peripherally between the spermatocytes. Thin cytoplasmic processes extend between the spermatocytes to the spermatids. These cytoplasmic processes vary in electron density from the cytoplasm of the germinal cells. These non-germinal cells closely resemble the vertebrate Sertoli cell.     

Effects of salinity and feeding on arm regeneration in the starfish Luidia clathrata (Say, 1825) (Echinodermata: Asteroidea)

The aim of this study was to determine: (1) salinity that maximizes arm regeneration in the starfish Luidia clathrata; and (2) if low food consumption or low salinity is the cause of the reduced rate of arm regeneration seen at low salinities.. An estimated salinity of 33 g kg^?1 produced maximum regeneration of two arms in L. clathrata. This salinity is typically greater than that found in bays that are the usual habitat for the species. Equivalent food consumption by L. clathrata in salinities of 20 g kg^?1 and 30 g kg^?1 resulted in greater regeneration in salinity of 30 g kg^?1, suggesting lower food consumption at low salinities is not the primary reason for lower regeneration. Higher food consumption compared to lower food consumption, both tested in salinity of 30 g kg^?1, did not increase regeneration, but resulted in more storage of energy in the pyloric caeca.     

Effect of 17β-Estradiol on Growth of Oocytes in Cultured Ovarian Fragments of the Starfish, Asterina Pectinifera

The development of growing oocytes of the starfish, Asterina pectinifera , was divided into five stages according to their histological features. Specimens collected monthly from Rishiri Island throughout a year were used. The effect of 17 β-estradiol on oocyte growth was investigated. When ovarian fragments taken from April females were cultured in artificial seawater containing Medium 199 and streptomycin sulfate for 3 days, oocytes within such fragments did not show any changes in diameter. However, when similar ovarian fragments were cultured in the presence of 10⁻⁵M 17 β-estradiol, the oocyte diameters increased significantly. It is concluded that 17 β-estradiol enhances the growth of starfish oocytes in cultured ovarian pieces.     

The effect of salinity on coelomic fluid osmolyte concentration and intracellular water content in Luidia clathrata (Say) (Echinodermata: Asteroidea)

• 1.1. The concentrations (mM) of osmolytes in the coelomic fluid of Luidia clathrata kept at 25‰S seawater (control individuals) were: 345, Na⁺; 10, K⁺; 10, Ca²⁺; 44, Mg²⁺; 387, Cl⁻; 0.67, amino acids; 0.09, NH₄⁺.
• 2.2. When individuals were transferred from 25‰S to 15‰S or 35‰S, the concentrations of inorganic ions in the coelomic fluid usually equilibrated within 24hr and became the same as those in the medium.
• 3.3. The intracellular water content (g intracellular H₂O/g solute-free dry tissue) of the pyloric caeca and tube feet of control individuals throughout the experiment was 2.13 and 5.40, respectively.
• 4.4. In tissues of individuals transferred to 15‰S, the intracellular water content increased by an average 50% in 12 hr but returned to 19% above control levels during 1 week.
• 5.5. In tissues of individuals transferred to 35‰S, the intracellular water content decreased by an average 17% in 12 hr and did not change during 1 week.
• 6.6. Luidia clathrata is an osmoconformer and partial cell volume regulator within the seasonal salinity range it encounters.

     

Effect of nutrition on the excretion rate of soluble nitrogenous products of Luidia clathrata (say) (Echinodermata; Asteroidea)

• 1.1. Groups of Luidia clathrata were fed maintenance level diets of Donax variabilis (50% protein by dry weight) or Penaeus duorarum (80% protein) or were starved.
• 2.2. The NH₄⁺ excretion rates for all treatments increased from 6.06 ± 2.55 to 14.39 ± 4.31 μg NH₄⁺ − N/g dry wt per hr after 20 days.
• 3.3. The urea excretion rate for all treatments was 1.25 ± 3.39 μg urea-N/g dry wt per hr for 56 days.
• 4.4. The pyloric caecum index (percentage of wet body weight) decreased 16.5 and 73.4%, for Donax variabilis-fed and starved sea stars, respectively. The pyloric caecum index of Penaeus duorarum-fed sea stars increased 81.5%. The protein level of the pyloric caeca was 47.00 ± 4.14% of the dry weight for the fed animals and 37% for the starved animals.
• 5.5. Increased NH₄⁺ excretion rates with starvation or presumed maintenance diets appear to be due to tissue catabolism.

     

Effect of partial decapitation (hypophysectomy) on 17β-estradioI secretion by the chick embryo ovary

Ovaries of equally matched partially decapitated (hypophysectomized) and sham-operated (at 42 h of incubation) 11 1/2-day-old chick embryos, i.e. embryos as identical as possible as regards body size and other morphological features, were compared with respect to the amounts of 17 beta-estradiol secreted during a 4 h-culture period. The 17 beta-estradiol secretion rate was very significantly lower in the decapitated than in the control embryos. This result suggests that the hypophysis controls 17 beta-estradiol secretion of the ovary in the 11 1/2-day old chick embryo.     

Glucosidase Activity in Acanthamoeba (Mayorella) palestinensis. The Effect of Glucose and Natural Glucosides on α- and β-Glucosidases

SYNOPSIS. Acanthamoeba ( Mayorella ) palestinensis produces high basal levels of α- and β -glucosidases, the latter being much more active than the former. Glucose, an essential growth substance, has a dual effect on the glucosidase activity. Growth concentrations (1%) of glucose inhibit, while low levels elevate the activity of both enzymes. Natural α-glucosides support growth in the same manner as glucose and raise the activity of both enzymes to the same extent. β -glucosides, on the other hand, are weak growth substrates, but stronger inducers, especially for β -glucosidase activity. The role of the glucosidases in the over-all metabolism of the ameba is discussed.     

A study on the 3β- and 17β-hydroxysteroid dehydrogenase activities in the gonads of Monopterus albus (Pisces: Teleostei) at various sexual phases during natural sex reversal

Activities of 3β-hydroxysteroid dehydrogenase (3β-HSD) and 17β-hydroxysteroid dehydrogenase (17β-HSD) in Monopterus gonads were studied at different sexual phases during natural sex reversal. Before sexual transformation, positive reactions for 3β-HSD in the follicular epithelium were found in the granulosa cells of some large, maturing follicles in some females during the breeding season. Weak reaction for this enzyme was also detected in some scattered interstitial cells found occasionally in some ovaries. At the intersexual and the male phases, intense 3β-HSD activities were demonstrated exclusively in the interstitial Leydig cells. No 17β-HSD activities were observable in the gonads at any stage of development. The reaction intensity of 3β-HSD in the interstitial cells exhibited a marked increase during the process of sex change from female to the intersexual and the male phases and there is a definite correlation with the density and nuclear size of these cells. It is concluded that in Monopterus , the granulosa cells in the ovary and the interstitial cells of the intersexual and male gonads are the major sites for the biosynthesis of oestrogens and androgens, respectively, and that the intensive development of interstitial tissue with increasing steroidogenic enzyme activities at the intersexual and male phases was directly related to the increase in androgen production in vitro reported previously. The occasional presence of some 3β-HSD positive interstitial cells in the ovary suggests that interstitial cell development might precede testicular lobule formation during natural sex reversal.     

Dynamics of excretion of 17α,20β-dihydroxy-4-pregnen-3-one 20-sulphate, and of the glucuronides of testosterone and 17β-oestradiol, by urine of reproductively mature male and female rainbow trout (Oncorhynchus myklss)

Levels of sulphated 17α20β-dihydroxy-4-pregnen-3-one (17,20 β -P; the oocyte maturation inducing steroid) in blood plasmas of sexually mature male and female rainbow trout Oncorhynchus mykiss , were very low in comparison to those of the free steroid. However, relatively large amounts were found in urine of both sexes.
Catheters were inserted into the urinary bladders of unovulated and ovulated females and of ripe-running males, and the fish then placed in spawning channels. Three-hourly urine samples were collected between 09.00 and 18.00 hours and then a 15-h sample between 18.00 and 09.00 hours the next morning. Measurements were made of 17,20 β -P-sulphale, testosterone glucuronide (T-G) and 17 β -oestradiol glucuronide (E2-G). In females, the highest rates of excretion of E2-G, T-G and 17,20 β -P-sulphate were found in unovulated, ovulating and ovulated females, respectively. The rates of excretion of 17,20 β -P-sulphate, T-G and E2-G in ovulated females were unaffected by the presence of a male. id males, however, there was a sharp increase in the rate of excretion of 17,20 β -P-suiphate and T-G in fish which were paired with an ovutated (nesting) female. A similar increase was found in males injected with male trout pituitary extract.     

The Influence of the Synthetic Growth Regulator α-Chloro-(β-(3-chloro-o-tolyl) propionitrile on Some Phytochrome-mediated Processes

In intact Sinapis alba seedlings the synthetic growth regulator α-chloro-β-(3-chloro-o-tolyl)propionitrile (PRB-8) inhibits the phytochrome-mediated anthocyanin synthesis, carotenoid synthesis and L-phenylalanine ammonia-lyase activity. This action was compared with that of other auxins and with that of α-chloro-β-(3-chloro-o-tolyl)propionitrile-homologues. From the results it appeared that PRB-8 and some other o-tolyl derivatives are more inhibitive than other known auxins.     

Pretreatment of Mouse Striatal Neurons in Primary Culture with 17β-Estradiol Enhances the Pertussis Toxin-Catalyzed ADP-Ribosylation of Gαo,i Protein Subunits

Pretreatment of striatal neurons from mouse embryos in primary culture with 17 beta-estradiol (10(-9) M, 24 h) enhanced the ADP-ribosylation of G alpha o,i proteins catalyzed by pertussis toxin (PTX). As estimated by quantitative ADP-ribosylation of G alpha s with cholera toxin and immunoblot experiments using anti-G alpha o and anti-G beta sera, 17 beta-estradiol pretreatment did not modify the levels of the major GTP-binding protein (G protein) constituent subunits G alpha s, G alpha o, and G beta. Thus, 17 beta-estradiol should induce a qualitative modification of these G proteins, perhaps by stabilizing the association of the heterotrimers G alpha o,i beta gamma, which are the targets of PTX. Such a hypothesis is in agreement with observations indicating that 17 beta-estradiol both suppressed the D2 dopamine- and opiate receptor-induced inhibitions of adenylate cyclase activity and enhanced the positive coupling between biogenic amine receptors (D1 dopamine, beta-adrenergic, and A2 adenosine) and adenylate cyclase. In addition, PTX pretreatment, which is known to uncouple receptors associated with Go,i proteins and thus to impair the dissociation of the heterotrimers G alpha o,i beta gamma, mimicks the effects of the steroid on the responses of adenylate cyclase to inhibitory and stimulatory agonists. Finally, the chemical specificity of the steroids was the same in the ADP-ribosylation as in the adenylate cyclase experiments: Testosterone (10(-9) M) mimicked the effects of 17 beta-estradiol, whereas 17 alpha-estradiol, progesterone, and dexamethasone did not.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evidence for a third allele at the β-lactoglobulin (β-Lg) locus of sheep milk and its occurrence in different breeds

Summary. Milk samples from 189 Merinoland Sheep, 145 Black Faced Mutton Sheep, 89 East Friesian Milk Sheep, 36 Rhön, 36 Pleven, 23 Tsigaja, 25 Black Razka and 86 Hungarian Merino x Pleven (F1) sheep were analysed by polyacrylamide gel electrophoresis under acid conditions and isoelectric focusing in ultrathin layer polyacrylamide gels with carrier ampholytes. Six different β-lactoglobulin (β-Lg) phenotypes (A, AB, B, AC, BC and C) were observed by both methods. The occurrence of three codominant alleles (β-Lg^A, β-Lg^B, β-Lg^c) at an autosomal locus (β-Lg) was supported by family and population data on genetic equilibrium. Differences in gene frequencies between the breeds were observed.     

Studies of the repressor (BlaI) of β-lactamase synthesis in Staphylococcus aureus

Purified BlaI, the putative repressor of the β-lactamase operon in Staphylococcus aureus , binds specifically to two regions of dyad symmetry (operators) located in the blaZ–blaR1 intergenic region. BlaI binds with similar affinity to the two regions and to the related sequence upstream of the mec gene found in methicillin-resistant strains of S. aureus , providing physical evidence for the cross-talk previously observed between these systems. A change from a lysine in the N-terminus of BlaI to an alanine or deletion of the C-terminal 23 amino acids severely reduces its DNA-binding ability, demonstrating the functional importance of both the N- and C-termini. An operator DNA–protein complex observed with crude cell lysates from repressed cells, indistinguishable from that observed with purified BlaI, was eliminated by induction of the β-lactamase operon. Furthermore, BlaI is proteolytically cleaved in response to the addition of inducer in a blaR1 -dependent manner, providing primary evidence for the molecular basis of induction. Thus, BlaI is shown to be the repressor of the β-lactamase system.     

The effects of 17β-oestradiol, testosterone and tamoxifen on the development of papillomata in Catostomus commersoni

Testosterone induced papillomata in 85% (11/13) of initially non-papillomatous white suckers Catostomus commersoni and increased papillomata growth in 100% (16/16) of initially papillomatous suckers. 17β-oestradiol induced papillomata in 83% (10/12) of initially nonpapillomatous suckers and increased papillomata growth in 100% (16/16) of initially papillomatous suckers. Less than 29% (4/14) of white suckers injected with tamoxifen developed papillomata, while complete papillomata regression was observed in 71% (10/14) of initially papillomatous suckers. In control groups 59% (27/46) of suckers either retained or developed papillomata and 27% (6/24) of suckers exhibited tumour regression. Protein kinase C (PKC) activity was significantly depressed and ornithine decarboxylase (ODC) activity was significantly elevated in steroid-treated papillomata v. normal lip epidermis. ODC activity was significantly depressed in tamoxifen-injected, regressing papillomata. There were no significant differences in plasma oestrogen and testosterone levels between papillomatous and nonpapillomatous female fish from a site contaminated with persistent organic chemicals and an uncontaminated reference site. Similarly, no significant differences in testosterone and 11-ketotestosterone levels were observed between papillomatous and non-papillomatous male fish.