Sex differences in the response of rats to drugs affecting GABAergic transmission

The administration of diazepam 1.0 mg/kg decreased the level of plasma corticosterone in female but not in male Wistar rats. Picrotoxin, another drug affecting GABAergic transmission, also brought about an increase of plasma corticosterone in both sexes. However, in order to achieve a plasma corticosterone increase of similar magnitude (more than 500%) a threefold higher dose of picrotoxin had to be given to males. When the convulsive properties of picrotoxin were tested, it became evident that the dose of picrotoxin (2.5 mg/kg) which was subconvulsive in male was almost 100% convulsive in female rats. The existing sex differences in the response of rats to drugs affecting GABAergic transmission might have possible implications in the treatment of GABA system dysfunction.     

Action of neurotensin on size, composition, and growth of pancreas and stomach in the rat

Since the gastrointestinal peptide neurotensin has a stimulatory effect on the secretion of the exocrine pancreas and an inhibitory effect on secretion and motility of the stomach, we investigated whether chronic parenteral administration of neurotensin would affect pancreatic and gastric growth. We therefore infused synthetic neurotensin subcutaneously (dose, 43 and 282 pmol X kg-1 X min-1) in 20 Wistar rats for 2 weeks using Alzet osmotic minipumps and compared pancreatic weight, DNA, RNA, protein, lipase, amylase, pancreatic polypeptide and insulin with these parameters in 10 control rats from the same litter with subcutaneously implanted plastic cylinders approximately the size of the minipumps. In another experiment, synthetic neurotensin (836 pmol X kg-1) was injected intraperitoneally three times a day for 3 days in 12 rats. Thereafter, we measured pancreatic DNA and in vitro incorporation of [3H]thymidine into pancreatic DNA. These effects were compared with the actions of caerulein and normal saline. Long term infusion of the high neurotensin dose induced an increase of pancreatic weight (control: 0.87 g, neurotensin: 1.02 g) and of DNA (control: 2.5 micrograms; neurotensin: 3.5 micrograms) and pancreatic polypeptide (control: 2.4 ng; neurotensin: 7.4 ng) contents, whereas pancreatic protein, RNA, amylase and lipase contents were not stimulated. In relation to DNA, these parameters even were significantly depressed. Insulin remained unchanged. Intraperitoneal injection of neurotensin induced an increase of pancreatic DNA content and stimulated [3H]thymidine incorporation into DNA (control: 11 000 dpm/g; neurotensin: 15 800 dpm/g pancreas). Moreover, long-term neurotensin infusion with the high dose led to a rise in protein concentration and an increase in the thickness of the gastric antrum; antral DNA concentration was insignificantly stimulated. Parenteral neurotensin in the doses and at the times administered, led therefore, to hyperplasia of the pancreas and induced growth of the gastric antrum. It is concluded that neurotensin can act as a trophic factor on pancreas and gastric antrum of the rat. It remains to be determined whether this represents a physiological effect of neurotensin.     

Formation of autophagosomes in the pinealocytes of the rat and Mongolian gerbil (Meriones unguiculatus): A lysosome wrapping mechanism?

Summary Autophagosome formation in rat and gerbil pinealocytes is described. It starts with the setting up of a tubular acid phosphatase-rich cisterna which gradually wraps around cytoplasmic areas to be catabolized. In light of obtained findings, it seems that the autophagosome formation in pinealocytes is a type of lysosome wrapping mechanism.     

Regression analysis of the spontaneous spike activity of neurons in snail ganglia

Regression analysis of the spontaneous spike activity of neurons in Helix pomatia was carried out with the aim to establish the statistical parameters of this activity under constant experimental conditions and during longer time intervals. The activity of 38 randomly chosen neurons in visceral and parietal ganglia, penetrated by microelectrodes and activated either endogenously by pacemaker potentials or by synaptic inputs, was recorded during time intervals lasting from 20 min to 3 h. The main results of the statistical analyses are presented in the table where the parameters of both cell types are listed. The validity of the regression analysis applied here is discussed from the point of the possibility it offers for carrying on the data processing quickly and without applying complex calculating means. The results are also considered regarding the current interest of our research group.     

Untersuchung der eiweißspindeln des kakteen-X-Virus mit fluoreszierenden Antikörpern

A?koliv na zá kladě mnoha pokus? se p? edpokládalo, ?e tzv. bÍlkovinná v?etena v buňkách tzn. buně?né inkluse X-viru kaktus? (Ca XV), jsou slo?ena z ?etních prodlou?ených ?ásti Ca XV, p?esto to dosud nebylo proká zá no. Proto jsme se pokusili pomocÍ fluoreskujÍcÍch protilátek doká ?at, ?e bilkovinná v?etena jsou skute?ně agregáty virových ?ástic. V těto práci jsme pouzili tzv. nep?Ímé metody. Nejprve jsme p? sobili na buňky obsahujÍci tato v?etena homologiokým antisé rem proti Ca XV, zÍskanym imunizacÍ králÍk? a teprve potom jsme buňky vlo?ili do roztoku fluoreskujicÍch protilátek proti králicimu γglobulinu. BÍlkovinná v?etena svitila potom ve fluorescen?nÍm mikroskopu silně ?lutozeleně (bylopou?ito fluoresceinisothiocyaná tu). Tato fluorescence ná m uká zala, ?e nastala pozitivnÍ reakce a ?e bÍlkovianá v?etena jsou slo?ena z virových ?ástic. ?etné kontrolnÍ pokusy potvrdily ná? základnÍ pokus.     

Importance de l'étude de la répartition écologique pour la taxonomie des éponges calcaires

Résumé 1. Les travaux deSarà (1953) et deBurton (1963) ont remis en question la valeur systématique des caractères morphologiques dans la classification des Eponges Calcaires, et ont proposé de considérer de nombreuses formes connues comme des variétés individuelles et régionales d'espèces très plastiques et variables. Nous avons essayé de préciser, par l'observation directe en plongée libre, la distribution et les préférences écologiques des Calcaires, de définir ainsi les limites naturelles de leurs populations, et d'étudier ensuite la variabilité des caractères morphologiques à l'intérieur de ces populations.2. Nous exposons ici l'exemple des espèces des genresClathrina etAscandra, étudiées en Adriatique, dans les régions de Marseille et de Roscoff. Leur distribution est en rapport direct et très précis avec l'exposition aux vagues et à la lumière, à tel point que sur une surface réduite plusieurs espèces se succèdent et se remplacent en fonction de l'exposition de l'endroit. Dans la règion de Roscoff cette distribution est plus large ce qui est dû aux effets des marées, mais les zones écologique préférentielles pour les espèces deClathrina ont pu être établies en fonction de l'importance de l'apport des sédiments par les eaux côtières.3. La possibilité de définir des populations dont la distribution est très précisemment délimitée malgré une coexistence dans un espace réduit, et qui ne sont pas réliées par les formes transitoires, permet d'éliminer l'hypothèse de la cospécificité de ces populations. Elle permet également d'établir les variations morphologiques possibles au sein d'une espèce, de retenir les caractères significatifs pour la classification, et finalement de distinguer les espèces qui se ressemblent morphologiquement. Dans le cas d'animaux qui, commeClathrina, possèdent très peu de caractères utilisables en systématique, c'est la seule façon de résoudre les problèmes de leur taxonomie.

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The importance of research on the ecological distribution for the taxonomy of calcareous sponges

The particular difficulties of the taxonomy of calcareous sponges are due to their great plasticity and their capacity for adaptation which obscure the natural limits of species. An attempt was made to define the natural populations of the Mediterranean species of the generaClathrina andAscandra through a study of their ecological distributions. The populations not connected by the transitory forms were defined by their ecological preferences, and, as they are found in a close cohabitation, were treated as having the specific values. The variability of different morphological features is discussed, the features significant for taxonomy are pointed out and the morphologically close species are defined.

     

Plastid transformation in greening scales of the onion bulb (Allium cepa,Alliaceae)

The greening of the upper part of the outerAllium cepa L. bulb scales, in particular along the vascular regions, is limited to the hypodermal cells in which typical leucoplasts are transformed to normal and functional chloroplasts. This process is light dependent and cannot afterwards be reversed or modified by darkness. The changes in fine structure are described and briefly discussed.Dedicated to Prof. DrLothar Geitler on the occasion of his 90th birthday and 55 years after the publication of his Grundriß der Cytologie.