Effect of penicillin on GABA-gated chloride ion influx

To investigate the mechanism of penicillin-induced convulsions, we have studied the effects of penicillin G (PC-G) on GABA-gated chloride ion influx in brain microsac preparations of mice. In the presence of 10^–4 M GABA, PC-G inhibited GABA-gated chloride ion influx in a dose-dependent manner. The dose-response curve for GABA in the presence of 10^–3 M PC-G was shifted rightward and there was a decrease in maximum response. The inhibitory effects of PC-G were not reversed by RO 15-1788, an antagonist of benzodiazepine (BZ) receptors, but were reversed by washing the microsac membranes. Therefore, PC-G probably exerts its proconvulsant effect by inhibiting GABA-gated chloride ion influx. However, it appears not to act through the BZ receptor of the GABA/BZ receptor complex.     

The anticonvulsant effect of citalopram on El mice,and the levels of tryptophan and tyrosine and their metabolites in the brain

Serotonin (5-HT) plays an important role in the seizures of El mice since the seizure threshold of El mice correlates with the 5-HT concentration in the central nervous system. In this study, the anticonvulsant effect of a 5-HT reuptake blocker, citalopram, was evaluated behaviorally and biochemically. El mouse convulsions were inhibited by oral administration of citalopram for 2 weeks. Citalopram increased tryptophan and tyrosine amounts, and decreased the 5-HT, 5-hydroxy-indoleacetic acid, kynurenine, and dopamine amounts in the brain. These findings show that citalopram depresses monoaminergic metabolism. Given the known convulsant effect of kynurenine, it is suggested that its decrease by citalopram may involve attenuation of El mice seizures.     

Euphausia superba dominates in the diet of Adélie penguins feeding under fast sea-ice in the shelf areas of Enderby Land in summer

Adélie penguins Pygoscelis adeliae in Enderby Land, Antarctica feed mainly on Euphausia superba during the chick rearing season in shelf areas where fast sea-ice remains: indicating that E. superba is abundant under the fast sea-ice in these areas. The shelf areas in Enderby Land, therefore, are unique since the previous studies of Adélie penguin diet in Ross Sea, Adélie Land and Prydz Bay show that E. crystallorophias is the most abundant krill species in shelf areas in general.     

Biosynthetic pathway of phytosiderophores in iron-deficient graminaceous plants: A new assay system for the detection of nicotianamine amino-transferase activity

A new assay system for the detection of nicotianamine amino-transferase activity was developed. The activity of nicotianamine amino-transferase which participated in biosynthetic pathway of MAs from methionine in graminaceous plants was induced by the iron deficiency treatment.     

Identification of a basic glycoprotein induced by ethylene in primary leaves of azuki bean as a cationic peroxidase.

Ethylene causes the accumulation of seven different proteins (each designated AZxx according to its molecular mass, xx in kD) in excised primary leaves of azuki bean (Vigna angularis) (F. Ishige, H. Mori, K. Yamazaki, H. Imaseki [1991] Plant Cell Physiol 32: 681-690). A complementary DNA encoding an ethylene-induced basic glycoprotein, AZ42, from azuki bean was cloned and its complete nucleotide sequence was determined. Characterization of the cDNA was accomplished by monitoring expression of an immunoreactive protein in Escherichia coli that harbored the cDNA and by the identification of a partial amino acid sequence that was the same as that determined from the purified protein. An open reading frame (1071 base pairs) in the cDNA encoded a protein of 357 amino acids with a molecular mass of 39.3 kD. The amino acid sequence contained three regions that are highly conserved among peroxidases from eight different plants. Purified AZ42 exhibited peroxidase activity. The basic glycoprotein induced by ethylene was identified as a cationic isozyme of peroxidase. The corresponding mRNA was not present in leaves that had not been treated with ethylene, but it appeared after 1 h of treatment with ethylene and its level increased for the next 15 h. Accumulation of the mRNA was also induced after wounding or treatment with salicylate. The wound-induced increase in the level of the mRNA was suppressed by 2,5-norbornadiene, but the salicylate-induced increase was not.     

The identification of a Caenorhabditis elegans homolog of p34cdc2 kinase

We have identified a Caenorhabditis elegans homolog of p34^cdc2 kinase. The C. elegans homolog, ncc-1, is ～-60% identical to p34^cdc2 of Homo sapiens. When expressed from a constitutive yeast promoter, ncc-1 is capable of complementing a conditional lethal mutation in the CDC28 gene of Saccharomyces cerevisiae, indicating that this C. elegans homolog can properly regulate the cell cycle.     

Analysis of simian immunodeficiency virus sequence variation in tissues of rhesus macaques with simian AIDS.

One rhesus macaque displayed severe encephalomyelitis and another displayed severe enterocolitis following infection with molecularly cloned simian immunodeficiency virus (SIV) strain SIVmac239. Little or no free anti-SIV antibody developed in these two macaques, and they died relatively quickly (4 to 6 months) after infection. Manifestation of the tissue-specific disease in these macaques was associated with the emergence of variants with high replicative capacity for macrophages and primary infection of tissue macrophages. The nature of sequence variation in the central region (vif, vpr, and vpx), the env gene, and the nef long terminal repeat (LTR) region in brain, colon, and other tissues was examined to see whether specific genetic changes were associated with SIV replication in brain or gut. Sequence analysis revealed strong conservation of the intergenic central region, nef, and the LTR. However, analysis of env sequences in these two macaques and one other revealed significant, interesting patterns of sequence variation. (i) Changes in env that were found previously to contribute to the replicative ability of SIVmac for macrophages in culture were present in the tissues of these animals. (ii) The greatest variability was located in the regions between V1 and V2 and from "V3" through C3 in gp120, which are different in location from the variable regions observed previously in animals with strong antibody responses and long-term persistent infection. (iii) The predominant sequence change of D-->N at position 385 in C3 is most surprising, since this change in both SIV and human immunodeficiency virus type 1 has been associated with dramatically diminished affinity for CD4 and replication in vitro. (iv) The nature of sequence changes at some positions (146, 178, 345, 385, and "V3") suggests that viral replication in brain and gut may be facilitated by specific sequence changes in env in addition to those that impart a general ability to replicate well in macrophages. These results demonstrate that complex selective pressures, including immune responses and varying cell and tissue specificity, can influence the nature of sequence changes in env.     

Genetic selection and the status of the embryo

In this paper I want to try to clarify the nature of the two different problems indicated in the title: there is a lively debate on whether or not genetic selection is a morally licit practice, and there are strong disagreements on whether or not the embryo is a person. I think that most of such controversies depend on confusions and/or unclearness about specific problems involved in each issue, I have no precise normative proposal on the morality of genetic selection, but I hope that my analysis will be helpful in avoiding some current confusions.     

Enhancing the structural diversity between forest patches—A concept and real-world experiment to study biodiversity,multifunctionality and forest resilience across spatial scales

Intensification of land use by humans has led to a homogenization of landscapes and decreasing resilience of ecosystems globally due to a loss of biodiversity, including the majority of forests. Biodiversity–ecosystem functioning (BEF) research has provided compelling evidence for a positive effect of biodiversity on ecosystem functions and services at the local (α-diversity) scale, but we largely lack empirical evidence on how the loss of between-patch β-diversity affects biodiversity and multifunctionality at the landscape scale (γ-diversity). Here, we present a novel concept and experimental framework for elucidating BEF patterns at α-, β-, and γ-scales in real landscapes at a forest management-relevant scale. We examine this framework using 22 temperate broadleaf production forests, dominated by Fagus sylvatica. In 11 of these forests, we manipulated the structure between forest patches by increasing variation in canopy cover and deadwood. We hypothesized that an increase in landscape heterogeneity would enhance the β-diversity of different trophic levels, as well as the β-functionality of various ecosystem functions. We will develop a new statistical framework for BEF studies extending across scales and incorporating biodiversity measures from taxonomic to functional to phylogenetic diversity using Hill numbers. We will further expand the Hill number concept to multifunctionality allowing the decomposition of γ-multifunctionality into α- and β-components. Combining this analytic framework with our experimental data will allow us to test how an increase in between patch heterogeneity affects biodiversity and multifunctionality across spatial scales and trophic levels to help inform and improve forest resilience under climate change. Such an integrative concept for biodiversity and functionality, including spatial scales and multiple aspects of diversity and multifunctionality as well as physical and environmental structure in forests, will go far beyond the current widely applied approach in forestry to increase resilience of future forests through the manipulation of tree species composition.