“Gomori-positive” neurosecretion in the rat after deafferentation of the medial basal hypothalamus

A portion of the "Gomori-positive" peptidergic neurosecretory (NS) cells in the paraventricular and especially in the supraoptic and postoptic nuclei degenerate three weeks after deafferentation of the medial basal hypothalamus. Most of the remaining NS cells show signs of high activity. Regenerating NS fibres form "muffs" around the blood vessels laterally from the lesion; some of them enter the "isolated" area or persist there if a thin layer of the brain tissue is left somewhere untouched under the basal end of the cut. The regenerating NS fibres are also found outside the nervous tissue: within the scar tissue, in the proliferating connective tissue of the brain sheet below the basal end of the cut and in the mantel plexus area. The NS fibres make close contact with blood vessels invading or penetrating the vascular wall. It is suggested that peptide neurohormones discharged from the "Gomori-positive" NS terminals enter the general blood circulation as well as the portal blood at the site of these newly formed axovasal contacts. It is supposed that under these conditions monoaminergic terminals do not discharge monoamines because no stimulation of monoamine-producing NS cells occurs with deafferentation.     

Polymerization of the Actin Component of the Cytoskeleton and Formation of the Geometry of a Cultured Nerve Cell (a Model Study)

Using mathematical modeling, we studied the biophysical aspects of the growth of the cell membrane and the growth of the actin network of the cytoskeleton of a neuron cultured on the rigid sublayer and the correlation between these processes. To describe the dynamics of the growth of the cytoskeleton limited by the cell membrane, we used the model of the thermal ratchet. Using the approaches of theoretical biophysics, we obtained a simple biophysical criterion that governs the selection of an alternative scenario of the formation of the cell, either growth of a single neurite or growth of a number of neurites. This criterion depends on the value of the adhesion between the cell and the substrate, the dimension of the actin monomer, and the thermal energy determining the frequency of thermal fluctuations of the cell membrane.     

Linear differentiation of cereal chromosomes

Summary The BSG test was used in a comparative study of the linear chromosome differentiation and the idiograms of T. Macha ssp. tubalicum v. letschchumicum Dek. et Men., T. georgicum Dek., T. timopheevi. Zhuk., T. carthlicum Nevski, T. dicoccum Schrank, v. rufum, T. durum Desf. v. Arnautka were compiled.The karyotype of each polyploid wheat species consists of two groups of chromosomes. The first is formed by ten pairs of constant chromosomes occurring almost in all species and the second by all the rest of the variable chromosomes that are either fully specific for the species in question or occur only in a few species. T. timopheevi largely differs from other species of polyploid wheats in the high level and specific localization of structural heterochromatin on chromosomes. The rols of introgression in wheat evolution and the necessity of establishing a General Cytological Nomenclature of Cereal Chromosomes are discussed.     

Correlation of the number of pineal “synaptic” ribbons and spherules with the level of serum melatonin over a 24-hour period in male rabbits

Summary Previous studies have shown that pineal synaptic ribbons and spherules may respond differently under normal and experimental conditions. It has been suggested that the increase in the number of ribbons may be a prerequisite for enhanced melatonin formation. In the present study, the number of ribbons and spherules as well as the level of serum melatonin were monitored over a 24-h period in the male rabbit, the pineal gland of which is known to contain many spherules. It was found that both the number of ribbons and the levels of serum melatonin show the typical nocturnal increase, exhibiting peaks at 02:00 and 06:00 h, respectively. There is a good correlation (R = 0.8) of the two parameters. The spherules, in contrast, show no statistically significant circadian changes in number and cannot be correlated with the levels of serum melatonin. It is concluded that ribbons and spherules may differ in function and that the ribbons may be somehow involved in the regulation of melatonin formation.Supported by the Deutsche Forschungsgemeinschaft (Grant Vo 135/7) within the project SPP Neuroendokrinologie     

Energy Metabolism of Synaptosomal Subpopulations from Different Neuronal Systems of Rat Hippocampus: Effect of L-Acetylcarnitine Administration In Vivo

The maximum rate (V_max) of some enzyme activities related to glycolysis, Krebs' cycle, acetylcholine catabolism and amino acid metabolism were evaluated in different types of synaptosomes obtained from rat hippocampus. The enzyme characterization was performed on two synaptosomal populations defined as large and small synaptosomes, supposed to originate mainly from the granule cell glutamatergic mossy fiber endings and small cholinergic nerve endings mainly arising from septohippocampal fiber synapses, involved with cognitive processes. Thus, this is an unique model of pharmacological significance to study the selective action of drugs on energy metabolism of hippocampus and the sub-chronic i.p. treatement with L-acetylcarnitine at two different dose levels (30 and 60 mg · kg^–1, 5 day a week, for 4 weeks) was performed. In control animals, the results indicate that these two hippocampal synaptosomal populations differ for the potential catalytic activities of enzymes of the main metabolic pathways related to energy metabolism. This energetic micro-heterogeneity may cause their different behaviour during both physiopathological events and pharmacological treatment, because of different sensitivity of neurons. Therefore, the micro-heterogeneity of brain synaptosomes must be considered when the effect of a pharmacological treatment is to be evaluated. In fact, the in vivo administration of L-acetylcarnitine affects some specific enzyme activities, suggesting a specific molecular trigger mode of action on citrate synthase (Krebs' cycle) and glutamate-pyruvate-transaminase (glutamate metabolism), but mainly of small synaptosomal populations, suggesting a specific synaptic trigger site of action. These observations on various types of hippocampal synaptosomes confirm their different metabolic machinery and their different sensitivity to pharmacological treatment.     

Expression and inheritance of kanamycin resistance in a large number of transgenic petunias generated by Agrobacterium-mediated transformation

One hundred and four kanamycin-resistant Petunia Mitchell plants were regenerated from leaf discs cocultivated with Agrobacterium tumefaciens strain LBA4404 containing a binary vector pCGN200. Selection for kanamycin resistance was applied during plant regeneration at the initiation of both shoots and roots. The regenerated plants were analysed for expression and inheritance of their kanamycin resistance phenotype. Approximately half of the plants showed normal Mendelian inheritance for one or two kanamycin resistance genes. In one case, the two copies were inserted at closely linked sites on homologous chromosomes, and gave <0.05% kanamycin-sensitive progeny on backcrosses. Six plants had inheritance patterns suggesting that the kanamycin gene had inserted into an essential region of DNA. Forty-five plants showed lower than expected transmission of kanamycin resistance, which was associated with low expression of the resistance phenotype in most cases. Ten plants produced segregation ratios that are not readily interpreted by Mendelian inheritance.     

Day-night differences in the number of pineal “synaptic” ribbons in two diurnal rodents,the chipmunk (Tamias striatus) and the ground squirrel (Spermophilus richardsonii)

Summary Daytime numbers of pineal synaptic ribbons higher than reported in the pineal gland of any other mammalian species were observed in two diurnal rodents, the eastern chipmunk and Richardson's ground squirrel. The number of synaptic ribbons was lower during the daytime and higher at night in both of these species.     

The air-blood barrier in the human lung

Summary The air-blood barrier was studied in replicas of freeze-fractured lung biopsies collected from healthy human subjects. Adjacent pneumocytes display a belt-like network composed of 3–7 superimposed ridges (fibrils) on the P face and complementary grooves on the E face, i.e., a structure corresponding to a tight junction. On the other hand, adjacent capillary endothelial cells show a continuous system of 2–4 membrane foldings. These appear mainly as smooth surfaced crests on the P face; on the E face furrows are seen, at the bottom of which a row of particles is situated. This arrangement suggests a leaky type of junction. Discontinuous occluding junctions are located in the pericytic venular segment of the alveolar vessels. The present findings are in agreement with previous physiological and ultrastructural tracer studies locating the main part of the diffusion barrier for small polar solutes and proteins in the alveolar epithelium. Communicating junctions are demonstrated between type I and type II pneumocytes, indicating intercellular cooperation between these cells of common embryonic origin, but which fulfill different functions in the adult. In the endothelium of the non-muscular alveolar vessels communicating junctions are lacking. Desmosomes occur in the epithelium between type I and type II pneumocytes; square arrays of particles characterize the plasma membrane of type I pneumocytes.A portion of this work was presented in partial fulfillment for the degree of Dr. med., Hannover Medical School     

The relation between the levels of extractable and diffusible IAA in almond fruits and their “June drop”

The relationship between the June drop of almond fruits(cv. Truoito) and the levels of extractable and diffusible IAA of the fruit wasstudied. June drop started almost simultaneously with thedecreasein the concentration of extractable free and ester IAA from seeds and theamountof diffusible free IAA from persisting fruits. The drop lasted for a period ofabout 17 days, during which time the auxin decreased constantly. In a secondexperiment, the relationship between fruit size, fruit drop and level of auxinwas examined. The fruits were classified according to size into threecategories, large, intermediate and small. Throughout the experiment thepercentage of small fruits that abscised (70%) was five times higher than thatof the other categories of fruits. The small persisting fruits had lower levelsof extractable free and diffusible free IAA than fruits of intermediate andlarge size. When the process of abscission advanced and the diffusion of theauxin had been interrupted, an increase in the concentration of extractablefreeand peptidic IAA in the seeds and pericarps of the abscising fruits wasobservedcompared with the persisting fruits.     

Present-Day State of Coral Reefs of Nha Trang Bay (Southern Vietnam) and Possible Reasons for the Disturbance of Habitats of Scleractinian Corals

Our investigations were conducted from 1990 to 2002. Sampling of bottom sediments and biological objects, as well as photo and video shooting, were performed during scuba diving. The state of the environment and coral reef communities was assessed using the chemical–analytical, fluorometric, and luminometric methods, as well as the Ames test and the transect technique. The research results suggest that the spectrum and distribution pattern of persistent congeners of PCDD/Fs (dioxins) in bottom sediments are similar to those of the defoliant Agent Orange and that the bottom sediments are toxic and display photo inhibition and a mutagenic effect. The bottom of the bay is heavily silted throughout its depth. Many large dead colonies of corals without mechanical damage were observed everywhere. The total coverage by live corals in all sites investigated does not exceed 30%. Although, without a doubt, many factors contributed much to the disturbance of the bay ecosystems, the actual trigger for the degradation of the coral reefs seems to be the input of dioxin-containing chemicals used as defoliants during the American–Vietnamese war (Vietnam War).     

Neurohormonal regulation of calcium in the cell

Neurohormone C (NC) is a glycopeptide isolated from bovine hypothalamus, which inhibits Ca-calmodulin (CaM)-dependent cAMP and cGMP phosphodiesterase (PDE) and is a regulator of Ca in the cell. Distribution of [⁴⁵Ca]CaCl₂ in the mitochondria and reticulum (SR) of heart and brain mitochondria and changes of Ca-binding proteins in these organelles under NC influence have been studied in the myocardium before and after isoproterenol-induced necrosis. Intraperitoneal administration of 80–100 mU of PDE inhibitory activity of NC to rats did not cause any noticeable changes in the protein content of intracellular organelles, but altered the affinity of certain proteins to⁴⁵Ca²⁺. This property of NC was especially noticable after isoproterenol necrosis. Necrotic injury of the myocardium induced Ca²⁺ storage in the mitochondria and SR of brain, and decreased the Ca²⁺ concentration in myocardial mitochondria. NC injection to the animals with necrosis was followed by Ca²⁺ release from all the studied organelles.     

Composition and photoinduced biosynthesis of the carotenoids of a protoplast-like Neurospora crass “slime” mutant

A spheroplast-like slime mutant of Neurospora crassa (lacking a rigid cell wall) was found to synthesize an identical spectrum of carotenoids as wild type strains except for -carotene. Furthermore strict photoregulation of the biosynthesis of these pigments as well as the characteristics of photoinduced carotenogenesis were also nearly identical in the mutant and in the wild type.     

The Activities of Six Exo- and Endopeptidases in the Substantia Nigra,Neostriatum, and Cortex of the Rat Brain

We determined the enzymatic activity and crude subcellular distribution of four exopeptidases: Dipeptidylaminopeptidase IV (DAP-IV), Alanyl aminopeptidase (AAP), Prolyl aminopeptidase (PAP) and -Glutamyl transpeptidase (GTP), and two endopeptidases: Postproline endopeptidase (PEP) and Trypsin-like peptidase (T-L P) in pars compacta (SNPC) and pars reticulata (SNPR) of substantia nigra, caudate-putamen (CAU) and cerebral cortex (CC) of the rat brain. We found: 1) DAP-IV activity is comparatively higher in SNPC and it is equally distributed in the postmitochondrial precipitate (PR) and supernatant (SN) fractions of SNPC, CAU and CC but higher in the SN from SNPR. 2) CC shows the highest activity of AAP and its activity is mainly located in the SN from all areas. 3) The activity of PAP is comparatively higher in SNPC and it is exclusively located in the SN from all areas. 4) GTP activity is similar in all areas but its predominance is in the SN for SNPC and SNPR, and in the PR for CAU and CC. 5) CAU has higher PEP activity (higher in the PR) than CC (higher in the SN); no activity is detected in the substantia nigra. 6) The activity of a Trypsin-like peptidase is the highest in SNPC and SNPR; this activity have some predominance in the SN and higher predominance in the same fraction from CAU and CC.     

Histochemical and chemical studies on pre- and postnatal development of the different systems of “short” and “long” adrenergic neurons in peripheral organs of the rat

Summary The adrenergic innervation in the submaxillary gland, heart, kidney, small intestine, and accessory male genital organs and the development of the adrenal chromaffin cells and the sympathetic ganglia were studied in the rat from 15 days post coitum to 16 days post partum using the fluorescence histochemical method of Falck and Hillarp. The postnatal development of the noradrenaline concentrations in the heart and vas deferens was followed by fluorometric determinations.At about 15 days post coitum, the anlagen of the sympathetic chains were well visible in the form of two dorsal segmented columns of small branching sympathicoblasts exhibiting an intense catecholamine fluorescence. In the midline, ventrally to these two anlagen, another column of sympathicoblasts developed; this seemed to give rise to the prevertebral ganglia and to the short adrenergic neurons supplying the internal genital organs. At the level of the adrenal anlagen, small intensely fluorescent chromaffin cells were collected in two bilateral groups which became enclosed by adreno-cortical cells. This enclosure was, however, not complete even at two weeks post partum.Bundles of growing sympathetic nerves were visible in the periphery of the various organs studied at 19–21 days post coitum. A terminal innervation of the organs suggestive of a functional transmitter mechanism did not start to establish until at or immediately after birth. The final pattern of innervation was usually reached at about one week post partum, and the following development proceeded largely in the form of a quantitative increase in the number of nerves participating in the innervation apparatus. The adult level of noradrenaline in the heart and vas deferens was reached three to five weeks after birth. The small intestine was an exception in that the final pattern of innervation in the wall was attained immediately after birth.There was no overt difference in the rate of development of the terminal sympathetic innervation in organs supplied by short adrenergic neurons (accessory male genital organs) compared to the innervation of the submaxillary gland, heart and kidney, which receive classical long adrenergic neurons.The work was supported by a grant from the Association for the Aid of Crippled Children, New York, and was carried out within a research organization sponsored by the Swedish Medical Research Council (grants No. B71-14X-56-07A and B71-14X-712-06A).     

The feeding ecology of a carnivorous plant (Pinguicula nevadense): prey analysis and capture constraints

Summary The taxonomic composition and size of arthropods captured by Pinguicula nevadense, an endemic carnivorous plant of the high-mountain zone of the Sierra Nevada (southern Spain), are analysed. The actual prey of P. nevadense and the available arthropods trapped by mimic-traps are compared, in order to identify the capture constraints of the plant. The results show that P. nevadense captures various arthropod taxa. Winged insects, especially Nematocera, make up the main component of the diet. The range of prey sizes in all P. nevadense populations studied is similar. The taxonomic composition of arthropods trapped by the mimic-traps is similar to that of the actual prey of P. nevadense. However, the plant captures prey only below a specific size threshold. These size constraints appear to be the principal factor determining the actual prey of this carnivorous plant.     

Colchicine effect on the chromosome number of barley embryos culturedin vitro

Summary The effect of colchicine upon the embryos of barley (Hordeum vulgare L.) culturedin vitro has been studied. Different concentrations of the drug as well as different times of culture in its presence have been tested, in order to ascertain the optimal conditions for the induction of non diploid cells. Tetraploid cells were always infrequent after the treatments, reaching the higher values during the first days of culture; aneuploid cells being frequent in some cases.