Effect of pinealectomy on plasma glucose, insulin and glucagon levels in the rat

In an attempt to know the role of the pineal gland on glucose homeostasis, the blood plasma concentrations of glucose, insulin and glucagon under basal conditions or after the administration of nutrients were studied in the jugular vein of conscious pinealectomized (Pn), melatonin-treated pinealectomized (Pn + Mel) and control (C) rats. Glucose levels were smaller in C than in Pn rats, while immunoreactive insulin (IRI) concentrations were significantly greater in C than in Pn rats. Contrary to this, immunoreactive glucagon (IRG) levels were significantly greater in Pn than in C animals. Melatonin treatment of Pn rats induces an increase of IRI concentrations and a reduction in IRG levels. Similar changes were obtained when hormonal determinations were carried out in portal blood plasma. Although ether anesthesia increases circulating glucagon levels in the porta and cava veins, the qualitative changes of plasma insulin and glucagon in Pn and Pn + Mel were similar to those found in conscious rats. To determine the effects of nutrients on pancreatic hormone release, intravenous arginine or oral glucose were administered to the animals of the three experimental groups. In C rats, both glucose and IRI levels reached a peak 30 minutes after glucose ingestion, decreasing thereafter. However, in Pn rats a glucose intolerance was observed, with maximum glucose and insulin concentrations at 60 minutes, while in Pn + Mel animals, glucose and IRI concentrations were in between the data obtained with the other two groups. Furthermore, glucose ingestion induced a significant reduction of IRG levels in all the groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of amphetamine-induced changes in the behavior of adult "aunts" on development and long term behavioral patterns of rats

Infant rats of the Wistar strain were kept either with their mother or with both the mother and the "aunt"--an adult virgin female during the suckling period. One group of aunts was injected regularly with amphetamine in the dose of 3 mg/kg b.w. (the AA group), another group with saline (the SA group). Control (CO) pups were reared by their mother only. Both acute and long term consequences of aunt-rearing on behavioral development and growth rate were observed. On Days 25 and 28 the SA pups displayed an increased exploratory activity level and more contacts with the litter-mate in the test of paired interactions when compared with both the AA and CO groups. The lowest frequency of exploratory, of manipulatory and social activities were recorded for the AA pups. In adulthood, both the aunt-reared groups of male rats exhibited higher activity level in a novel environment than the CO males. However, while in the CO and the SA males the activity level tended to habituate over the repeated tests, in the AA it persisted on a high level. The difference among females was not significant. Growth rate was retarded in the AA male and female rats.     

Paternal age and the occurrence of birth defects

The association between paternal age and the occurrence of birth defects was studied using data collected in Metropolitan Atlanta. Paternal-age information for babies born with defects was obtained from birth certificates, hospital records, and interviews with mothers; for babies born without defects, the information was obtained from birth certificates. Several statistical techniques were used to evaluate the paternal-age-birth-defects associations for 86 groups of defects. Logistic regression analysis that controlled for maternal age and race indicated that older fathers had a somewhat higher risk for having babies with defects, when all types of defects were combined; an equivalent association for older mothers was not found. Logistic regression analyses also indicated modestly higher risks for older fathers for having babies with ventricular septal defects and atrial septal defects and substantially higher risks for having babies with defects classified in the category chondrodystrophy (largely sporadic achondroplasia) and babies with situs inversus. An association between elevated paternal age and situs inversus has not been reported before; the magnitude of the estimated increased risk for situs inversus was about the same as that found in this study for chondrodystrophy.     

The relationship between maternal age and chromosome size in autosomal trisomy.

The pattern of maternal age-specific incidence of autosomal trisomy in spontaneous abortions was examined for each chromosome for which a sufficient number of trisomies was observed. This included chromosomes 2, 4, 7-10, 13-16, 18, and 20-22. The rate of increase after age 30 for each of the small chromosomes (groups D-G) was similar, with the exception of chromosome 16, which showed a significantly shallower rate. The C group chromosomes tended to have an intermediate rate of increase after age 30, with the exception of chromosome 7, which had a pattern similar to the smaller chromosomes. The larger chromosomes (2 and 4) had the smallest rate of increase. There was a significant relationship between chromosome size and rate of increase after age 30 (after excluding chromosome 16), but not with rate of increase before age 30. The results suggest that autosomal trisomies may be of heterogeneous origin, with a maternal age-related factor associated with chromosome size and other sources unrelated to chromosome size. Additional evidence for and against this hypothesis is discussed.     

Inactivation of human and simian rotaviruses by chlorine.

The inactivation of simian rotavirus SA-11 and human rotavirus type 2 (Wa) by chlorine was compared at 4 degrees C by using single-particle virus stocks. Both virus types were usually more readily inactivated at pH 6.0 than at pH 8.0 when low chlorine concentrations (0.05 to 0.2 mg/liter) were used. A complete (5 log) reduction of both was obtained within 20 s at all pH levels when chlorine concentrations were increased to 0.3 mg/liter. Slight differences in the chlorine sensitivities of SA-11 and human rotavirus type 2 were noted but were not considered to be significant.     

Glutamicin CBII,a bacteriocin-like substance produced by

Corynebacterium glutamicum CBII, in the stationary phase of growth, was found to produce spontaneously a substance resembling bacteriocins by its bactericidal properties. This substance designated glutamicin CBII was observed to exhibit bactericidal activity against coryneform bacteria (12 species tested) but not against unrelated gram-positive (3) and gram-negative (3) bacteria, while its action on bacteria with no quite known relatedness to the coryneform group (14) was found to be variable. Glutamicin CBII was partially purified by precipitation with ammonium sulphate (70% saturation), selective heat precipitation and gel chromatography on Sepadex G-50. The antibacterial substance diffused through cellophane membrane with an approximate cut-off of 10000 dalton and its sedimentation coefficient was determined to be 1.1. S by ultracentrifugation. Heating at 100°C for 30 min had no effect on its activity. Glutamicin CBII was proved to be resistant to chloroform, trypsin, chymotrypsin, pronase, and subtilisin. According to its staining behaviour and ¹H NMR spectra it probably represents a glycoprotein containing only a minor protein component.

---

     

Comparison of the enzymatic behavior of high molecular weight and free lysyl-tRNA synthetase from rat liver: kinetic analysis of lysylation of tRNA

Lysyl-tRNA synthetase occurs in the high molecular weight form in rat liver. The high molecular weight lysyl-tRNA synthetase has been previously demonstrated to exist as multienzyme complexes of aminoacyl-tRNA synthetases. The multienzyme complexes can be dissociated by hydrophobic interaction chromatography and yield fully active, free lysyl-tRNA synthetase. The free form is found to be twice as active as the complexed form in lysylation. Bisubstrate and product inhibition kinetics of lysylation are systematically carried out for highly purified free lysyl-tRNA synthetase and the 18 S synthetase complex. Surprisingly, the two enzyme forms exhibit distinctly different kinetic patterns in bisubstrate and product inhibition kinetics under identical conditions. The 18 S synthetase complex shows kinetic patterns consistent with an ordered bi uni uni bi ping pong mechanism, while the results of free lysyl-tRNA synthetase do not. We conclude that structural organization of lysyl-tRNA synthetase beyond quaternary structure of proteins may alter the enzyme behavior.     

Analysis of a large nontranscribed spacer in the ribosomal DNA of the house cricket,Acheta domesticus (Orthoptera:Gryllidae)

An analysis of a 29-kilobase nontranscribed spacer fragment in the ribosomal DNA (rDNA) of the house cricket, Acheta domesticus, revealed a highly repetitious structure. A total of eight EcoRI repeats of three different size classes measuring 259, 420, and 508 base pairs (bp) was mapped to a region 2 kilobases (kb) from the 18 S coding region. The repeats were oriented in a nonrandom manner and had sequences homologous to DNA located immediately adjacent to the repetitive array. DNA sequence analysis showed that the repetitive region was composed of smaller direct repeats 66, 67, and 383 bp in length. There was minor length heterogeneity of the chromosomal restriction fragments containing the entire array, indicating that a variable number of EcoRI repeats is a minor contributor to the total repeat-unit length heterogeneity. Immediately upstream from the EcoRI array there is a 17-kb region composed of 50 to 60 subrepeat elements recognized by a variety of restriction endonucleases. A subcloned SmaI repeat from the array was not homologous to any other part of the rDNA repeat unit or other chromosomal DNA. There was little length heterogeneity in restriction fragments containing the chromosomal 17-kb repetitions region. Immediately upstream from the 17-Kb region there is a 4.1-kb segment with sequences homologous to the EcoRI repeats.     

The reproductive biology of a tropical cyprinid, Hampala macrolepidota (Van Hasselt), from Zoo Negara Lake, Kuala Lumpur, Malaysia

From a study on some aspects of the reproductive biology of the tropical cyprinid Hampala macrolepidota (Van Hasselt) in Zoo Negara Lake, Kuala Lumpur, Malaysia, analyses of the maturity stages, gonadosomatic indices and oocyte diameter patterns show that this fish is able to spawn throughout the year. However, physicochemical and environmental factors determine the actual spawning time of this fish. Spawning activity is associted with decreasing temperatures and daylengths, rising water levels and increasing turbidities. Spawning is protracted and coincides with the rainy season which extends from November to March the following year.