Synchronous dynamics and rates of extinction in spatially structured populations

We explore extinction rates using a spatially arranged set of subpopulations obeying Ricker dynamics. The population system is subjected to dispersal of individuals among the subpopulations as well as to local and global disturbances. We observe a tight positive correlation between global extinction rate and the level of synchrony in dynamics among thesubpopulations. Global disturbances and to a lesser extent, migration, are capable of synchronizing the temporal dynamics of the subpopulations over a rather wide span of the population growth rate r. Local noise decreases synchrony, as does increasing distance among the subpopulations. Synchrony also levels off with increasing r: in the chaotic region, subpopulations almost invariably behave asynchronously. We conclude that it is asynchrony that reduces the probability of global extinctions, not chaos as such: chaos is a special case only. The relationship between global extinction rate, synchronous dynamics and population growth rate is robust to changes in dispersal rates and ranges.     

Glycogen in honeybee queens,workers and drones (Apis mellifera carnica Pollm.)

Honey bees (Apis mellifera carnica Pollm.) have low glycogen reserves in summer. Upon emergence drones have significantly larger amounts per unit weight when emerging, than workers; perhaps as adaption to the risk of not being fed as intensely as young workers. Maximum content was 0.23mg for workers (28d), and 0.59mg for drones (after emergence). Workers have relatively constant glycogen contents during their life, and very young drones have more glycogen than older ones. Young queens are similar to workers. In workers and queens in summer the greatest amounts of glycogen are found in the thorax. When the bees start flying (6th-8th day of life), drones have the highest amounts in the head (probably to supply their eyes), and upon maturity, drones have the least glycogen in the abdomen.Workers in winter show different glycogen values depending on whether they are active bees from the core area (0.23mg) or inactive ones from the outer surface of the winter cluster (0.37mg). They use glycogen from the thorax and the abdomen for their ongoing energy need.     

Are Elevated Aminotransferases and Decreased Bilirubin Additional Characteristics of the Metabolic Syndrome?

Abnormal liver tests, as well as morphological changes in the liver, are frequent among obese patients. Other frequent disturbances are visceral fat accumulation, insulin resistance, non-insulin-dependent diabetes mellitus (NIDDM), hypertriglyceridemia, and hypertension; these are a set of aberrations known as the metabolic syndrome. In order to investigate a possible relationship between the metabolic syndrome and impaired liver status we examined associations between liver tests, metabolic variables (insulin, glucose, and triglycerids), body composition and nutrition in 1083 men (BMI 28.8–63.8 kg/m²) and 1367 women (BMI 26.7–68.0 kg/m²) in the ongoing intervention study of Swedish Obese Subjects (SOS). Standard biochemical techniques were used to assess liver status and metabolic variables. Lean body mass (LBM) and masses of visceral and subcutaneous adipose tissue (AT) were estimated by means of computed tomography (CT) calibrated anthropometric equations. In both genders aspartate aminotransferase and alanine aminotransferase were, or tended to be, positively correlated to fasting serum insulin, visceral AT (women), and alcohol intake. In women, the aminotransferases were also correlated with fasting blood glucose. In both genders alkaline phosphatase was, or tended to be, positively associated with visceral AT, insulin (women), and glucose. Bilirubin was negatively correlated to insulin and visceral AT in men and women. Additional multivariate analyses indicated that alcohol had less explanatory power than serum insulin for the examined liver tests, especially among women. These results suggest that pathological liver tests in the obese may represent an expression of the metabolic syndrome.     

Immunohistochemical localization of bioactive peptides and amines associated with the chromaffin tissue of five species of fish

Biogenic peptides and amines associated with the chromaffin tissue in Atlantic cod (Gadus morhua), rainbow trout (Oncorhynchus mykiss), European eel (Anguilla anguilla), spiny dogfish (Squalus acanthias) and Atlantic hagfish (Myxine glutinosa) were identified utilizing immunohistochemical techniques. Within the posterior cardinal vein (PCV) in cod, trout and eel, a subpopulation of chromaffin cells displayed immunoreactivity to tyrosine hydroxylase (TH) and dopamine--hydroxylase (DH) but not to phenylethanolamine-N-methyltransferase (PNMT). TH-like immunorectivity was observed within cells in hagfish hearts. Nerve fibres displaying vasoactive intestinal peptide (VIP) immunoreactivity and pituitary adenylyl cyclase activating peptide (PACAP) immunoreactivity innervated cod, trout and ell chromaffin cells. In eel, neuropeptide Y (NPY)-like and peptide YY (PYY)-like immunoreactivity was located within cells in the PCV, including chromaffin cells. Serotonin-like immunoreactivity was observed within eel and cod chromaffin cells and in hagfish hearts. In the dogfish axillary bodies, nerves displaying TH-like, VIP-like, PACAP-like, substance P-like and galanin-like immunoreactivity were observed. These results are compared with those of other vertebrates, and potential roles for these substances in the control of catecholamine release are suggested.     

Chemical characterization of two lipopolysaccharide species isolated from Rhizobium loti NZP2213

Phenol-water extraction of Rhizobium loti NZP2213 cells allowed a simultaneous isolation of two structurally different lipopolysaccharides, from the aqueous (LPS-W) and phenol (LPS-P) phase that differed in their sodium doexycholate-PAGE pattern and composition. LPS-W showed a profile indicating an R-type LPS; LPS-P had a cluster of poorly resolved bands in the high-molecular-weight region. LPS-P contained large amounts of 6-deoxy-l-talose (6dTal), and a small amount of 2-O-methyl-6-deoxy-talose (molar ratio 30:1), both of which were completely absent in LPS-W. Methylation analysis gave only one major product, 2,4-di-O-methyl-6dTal, indicating that the O-chain is composed of a homopolymer of 1,3-linked 6dTal, having the methylated 6dTal (2-O-me-6dTal) probably localized at the non-reducing end of the O-chain. This homopolymeric O-chain was additionally O-acetylated, as evidenced by GC-MS and by ¹³C NMR analysis. The lipid A moieties of both LPS-W and LPS-P showed almost identical composition, with six, different 3-OH fatty acids and with two, so far not described, long-chain 4-oxo-fatty acids, all being amide-linked, and with 27-OH-28:0 as the main ester-linked fatty acid. Lipid A was of the lipid A_DAG-type, i.e., having a (phosphorylated) 2,3-diamino-2,3-dideoxy-d-glucose-containing lipid A backbone. Lipid A_DAG is widespread among species of the -2 group of Proteobacteria, but has so far not been encountered in any other rhizobial or agrobacterial species.     

Ribonuclease P from plant nuclei and photosynthetic organelles

RNase P consists of both protein and RNA subunits in all organisms and organelles investigated so far, with the exception of chloroplasts and plant nuclei where no enzyme-associated RNA has been detected to date. Studies on substrate specificity revealed that cleavage by plant nuclear RNase P is critically dependent on a complete and intact structure of the substrate. No clearcut answer is yet possible regarding the order of processing events at the 5 or 3 end of tRNAs in the case of nuclear or chloroplast processing enzymes. RNase P from a phylogenetically ancient photosynthetic organelle will be discussed in greater detail: The enzyme from theCyanophora paradoxa cyanelle is the first RNase P from a photosynthetic organelle which has been shown to contain an essential RNA subunit. This RNA is strikingly similar to its counterpart from cyanobacteria, yet it lacks catalytic activity. Properties of the holoenzyme suggest an intermediate position in RNA enzyme evolution, with an eukaryotic-type, inactive RNA and a prokaryotic-type small protein subunit. The possible presence of an RNA component in RNase P from plant nuclei and modern chloroplasts will be discussed, including a critical evaluation of some criteria that have been frequently applied to elucidate the subunit composition of RNase P from different organisms.Abbreviations RNase P Ribonuclease P - (pre-)tRNA transfer ribonucleic acid (precursor) - tRNA ^Ser (- ^Tyr , - ^Phe ) transfer ribonucleic acid specific for serine (tyrosine, phenylalanine) - CyRP RNA RNA component of cyanelle RNase P     

Direct molecular analysis of the fragile X syndrome in a sample of Egyptian and German patients using non-radioactive PCR and Southern blot followed by chemiluminescent detection

Molecular genetic analysis of individuals from 6 Egyptian and 33 German families with fragile X syndrome and 240 further patients with mental retardation was performed applying a completely non-radioactive system. The aim of our study was the development of a non-radioactive detection method and its implementation in molecular diagnosis of the fragile X syndrome. Furthermore, we wanted to assess differences in the mutation sizes between Egyptian and German patients and between Egyptian and German carriers of a premutation. Using non-radioactive polymerase chain reaction (PCR), agarose gel electrophoresis and blotting of the PCR products, followed by hybridisation with a digoxigenin-labelled oligonucleotide probe (CGG)₅ and chemiluminescent detection, we identified the fragile X full mutation (amplification of a CGG repeat in the FMR-1 gene ranging from several hundred to several thousand repeat units) in all patients. We observed no differences in the length of the CGG repeat between the Egyptian and German patients and carriers, respectively. However, in one prenatal diagnosis, we detected only one normal sized allele in a female fetus using the PCR-agarose assay, whereas Southern blot analysis with the digoxigenin labelled probe StB 12.3 revealed presence of a full mutation. Our newly established nonradioactive genomic blotting method is based on the conventional radioactive Southern blot analysis. Labelling of the probe StB 12.3 with digoxigenin via PCR allowed the detection of normal, premutated and fully mutated alleles. For exact sizing of small premutated or large normal alleles, we separated digoxigenin labelled PCR products through denaturing poly-acrylamide gelelectrophoresis (PAGE) and transfered them to a nylon membrane using a gel dryer. The blotted PCR-fragments can easily be detected with alkaline phosphate-labelled anti-digoxigenin antibody. The number of trinucleotide repeat units can be determined by scoring the detected bands against a digoxigenated M13 sequencing ladder. Our newly developed digoxigenin/chemiluminescence approach using PCR and Southern blot analysis provides reliable results for routine detection of full fragile X mutations and premutations.     

Two recurrent nonsense mutations and a 4 bp deletion in a quasi-symmetric element in exon 37 of the NF1 gene

We screened a total of 92 unrelated patients with neurofibromatosis type 1 (NF1) for mutations in exon 37 of the NF1 gene, by using temperature gradient gel electrophoresis. Two novel mutations were found: a 4 bp deletion in a so-called quasi-symmetric element (6789delTTAC) and a recurrent nonsense mutation, which was identified in two unrelated patients, at codon 2264 (C6792A). The independent origin of the latter mutation in two families was confirmed by haplotype analysis. The nonsense mutation and the 4 bp deletion are both predicted to lead to a truncated protein product lacking the Cterminal 20% (aproximately) of its sequence. The occurrence of three independent mutations among 92 NF1 patients at codons 2263–2264 (exon 37) suggests that a specific search for mutations in this area should be undertaken in screening programs for NF1 mutations.