Plasma catecholamines: effects of footshock level and hormonal modulators of memory storage

Plasma levels of norepinephrine (NE) and epinephrine (EPI) were measured in male Sprague-Dawley rats before and at several times after training injections of agents known to enhance or to impair later retention performance for a one-trial inhibitory (passive) avoidance task. Two days before testing, each animal was surgically prepared with a chronic tail artery catheter that allows for repeated blood sampling in unhandled rats. Exposure to a single, intense training footshock (3.0 mA, 2.0 sec duration) resulted in an immediate but transient increase in plasma levels of EPI and to a lesser extent NE. Plasma levels of both catecholamines did not differ between unshocked controls and animals that received a weak training footshock (0.6 mA, 0.5 sec duration). An injection of EPI at a dose that enhances retention performance (0.1 mg/kg, sc) resulted in increments in plasma EPI levels of 0.8-1.9 ng/ml from 5 to 40 min after injection. An injection of EPI (0.5 mg/kg, sc) at a dose that produces retrograde amnesia resulted in increments in plasma EPI ranging from 3.7 to 4.5 ng/ml during the 40 min after injection. Plasma NE levels were not significantly altered following an EPI injection. A single injection of adrenocorticotropin (ACTH, 0.3 or 3.0 IU per rat) did not alter the plasma catecholamine responses to training with a weak footshock. Similarly, the synthetic ACTH analog, Organon 2766 (125 or 250 mg/Kg) did not affect plasma catecholamines in untrained (unshocked) rats.These results demonstrate that significant increments in plasma levels of NE and EPI occur shortly after inhibitory avoidance training. Furthermore, an injection of EPI that enhances retention of an inhibitory avoidance task mimics the magnitude, though not the temporal characteristics, of the endogenous adrenal medullary response to a training footshock. Other hormonal treatments (ACTH and Organon 2766) which enhance memory storage do not affect plasma levels of NE and EPI.     

Isolation,origin and properties of enucleate plant microplasts

Summary Auxin-induced highly vacuolated thin-walled callus cells of several plant species, when ruptured, released large numbers of subcellular units most of which were enucleate. These enucleate microplasts are surrounded by an inner membrane of the cell, most probably derived from the tonoplast. When microplasts isolated fromSaintpaulia callus were cultured in a medium supplemented with growth substances they formed a thin wall and underwent budding. Microplasts could be useful for various studies in plant cell biology and for genetic manipulations.     

The structure of 180° supernumerary limbs and a hypothesis of their formation

The results of a detailed analysis of 100 supernumerary limbs generated by 180° ipsilateral rotation (on the same limb stump) of regeneration blastemas is presented. The limbs were analyzed in terms of their position of origin, frequency, cartilage structure by Victoria blue staining, and muscle structure by serial sections. Single, double, or triple supernumeraries can be produced at no unique position of origin, although the posterodorsal quadrant was preferred. Four classes of supernumerary limbs were generated by such operations—normal; double dorsal or double ventral; part normal/part mirror imaged; part normal/part inverted in approximately equal frequencies. After amputation of these supernumeraries the same muscle patterns are faithfully regenerated. A hypothesis to explain the production of these abnormal limbs is proposed based on the observed phenomenon of fusion of supernumerary blastemata, but their regenerative behaviour presents problems for current models of pattern formation. Similar results have been obtained with developing limb buds and the relation between development and regeneration is discussed.     

Interleukin-1-β and Tumor Necrosis Factor-α Increase Peripheral-Type Benzodiazepine Binding Sites in Cultured Polygonal Astrocytes

Peripheral-type benzodiazepine binding sites (PTBBS) are markedly increased in the injured CNS. Astrocytes appear to be the primary cell type which express increased PTBBS. Because certain cytokines within the injured CNS are potent mitogens for astrocytes, we examined the effects of two such cytokines, interleukin (IL)-1 beta and tumor necrosis factor (TNF), on PTBBS in cultured astrocytes using [3H]Ro 5-4864 as the specific ligand. Purified cultures of either polygonal or process-bearing astrocytes were prepared from neonatal rat cerebral hemispheres. At a concentration of 1.8 nM, specific binding of the radioactive ligand to polygonal astrocytes reached equilibrium within 60 min and was half-maximal by 5-10 min. By contrast, specific binding to process-bearing astrocytes barely exceeded background levels. IL-1 and TNF increased PTBBS within polygonal astrocytes in both dose- and time-dependent manners. At 10-50 ng/ml, IL-1 beta and TNF-alpha elevated [3H]Ro 5-4864 binding in polygonal astrocyte cultures 65 and 87%, respectively, above the level in control cultures. However, no changes in PTBBS were seen within polygonal astrocytes after IL-2 treatment. Scatchard analysis of saturation binding experiments suggested that the increase in PTBBS promoted by TNF was due to an increased number of binding sites present in polygonal astrocytes and not due to an increase in receptor affinity. Binding data suggested that PTBBS within cultures of process-bearing astrocytes were virtually absent irrespective of the treatment. These in vitro data suggest that certain cytokines found in the injured brain may be involved in up-regulating PTBBS within a particular subtype of astrocyte.     

Functional analysis of a miRNA‐like small RNA derived from Bombyx mori cytoplasmic polyhedrosis virus

Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) is a major pathogen of the economic insect silkworm, Bombyx mori. Virus‐encoded microRNAs (miRNAs) have been proven to play important roles in host–pathogen interactions. In this study we identified a BmCPV‐derived miRNA‐like 21 nt small RNA, BmCPV‐miR‐1, from the small RNA deep sequencing of BmCPV‐infected silkworm larvae by stem‐loop quantitative real‐time PCR (qPCR) and investigated its functions with qPCR and lentiviral expression systems. Bombyx mori inhibitor of apoptosis protein (BmIAP) gene was predicted by both target prediction software miRanda and Targetscan to be one of its target genes with a binding site for BmCPV‐miR‐1 at the 5′ untranslated region. It was found that the expression of BmCPV‐miR‐1 and its target gene BmIAP were both up‐regulated in BmCPV‐infected larvae. At the same time, it was confirmed that BmCPV‐miR‐1 could up‐regulate the expression of BmIAP gene in HEK293T cells with lentiviral expression systems and in BmN cells by transfecting mimics. Furthermore, BmCPV‐miR‐1 mimics could up‐regulate the expression level of BmIAP gene in midgut and fat body in the silkworm. In the midgut of BmCPV‐infected larvae, BmCPV‐miR‐1 mimics could be further up‐regulated and inhibitors could lower the virus‐mediated expression of BmIAP gene. With the viral genomic RNA segments S1 and S10 as indicators, BmCPV‐miR‐1 mimics could up‐regulate and inhibitors down‐regulate their replication in the infected silkworm. These results implied that BmCPV‐miR‐1 could inhibit cell apoptosis in the infected silkworm through up‐regulating BmIAP expression, providing the virus with a better cell circumstance for its replication.     

Variants of the Varimax Rotation Method

In the present paper we present an example proving that the Varimax rotation method commonly used in factor analysis (see H. F. KAISER, 1958) need not give a unique solution. We also show that changing the original algorithm more than one local maximum of the criterion “V” can be achieved. Hence the loadings of factors and practical interpretations of solutions are affected in this way.     

GRF-induced feeding: Evidence for protein selectivity and opiate involvement

Growth hormone-releasing factor (GRF) is a hypothalamic peptide named for its ability to induce release of growth hormone from the anterior pituitary. GRF also acts as a neurotransmitter in the suprachiasmatic nucleus/medial preoptic area (SCN/MPOA) to stimulate food intake. The purpose of this series of experiments was to explore the nature of GRF-induced feeding, with a particular emphasis on macronutrient selectivity, and to examine the role of opiate activity in the paraventricular nucleus of the hypothalamus (PVN). Chow intake stimulated by GRF microinjection (1 pmol/0.5 μl) into the SCN/MPOA was blocked by injection of methyl-naltrexone (3 μg/0.5 μl) into the PVN. In animals habituated to macronutrient diets (Teklad, WI), GRF preferentially stimulated intake of protein at 2 and 4 h postinjection, whereas it had no effect on carbohydrate intake. Further, this effect was blocked by injection of naloxone (40 nmol/0.5 μl) into the PVN. Microinjection of morphine (0, 1, 10, and 17 μg/0.5 μl) into the PVN also specifically stimulated protein intake at 2 and 4 h postinjection. These results suggest that feeding derived from GRF actions in the SCN/MPOA is macronutrient selective, and is dependent on PVN opiate activity for expression.     

Continuous-flow NMR culture system for mammalian cells

A continuous-flow NMR culture system for mammalian cells has been developed on which ³¹P-NMR experiments under complete and strictly physiologic conditions have been performed. Observations on the response of the cellular metabolism to stresses such as starvation, low temperature and changes in environmental pH monitored by ³¹P-NMR are reported. The response of the intracellular pH relative to the external pH of the growth medium is studied. We find that under the experimental conditions used there exists a ΔpH varying between less than 0.2 and more than 0.6 pH units. These results are compatible with those obtained using other techniques.     

Seasonal changes of the ultrastructure of the pars tuberalis of the hypophysis of Rana temporaria

Summary In the pars tuberalis of the hypophysis of Rana temporaria, which shows the ultrastructural characteristics of a polypeptide hormone secreting endocrine gland, seasonal changes of the ultrastructure are described. In accordance with the literature, these seasonal changes of ultrastructure are interpreted as the morphological expression of seasonal changes of endocrine activity of the pars tuberalis.