A microspectrofluorometric analysis of nuclear and chloroplast DNA in Volvox

Nuclear division immediately follows nuclear DNA doubling in all stages of the life cycle examined in the green alga Volvox; fluorescence microfluorometry of individual cells revealed no evidence of prolonged accumulation of nuclear DNA prior to mitosis in reproductive cells. Somatic cell nuclear DNA quantity is unaffected by developmental events in gonidia of the same spheroid; it remains constant from the end of cleavage until the death of the cell. In reproductive cells, chloroplast DNA replication precedes nuclear replication. The sites of plastid DNA accumulation, made visible by use of the fluorochrome 4′,6-diamidino-2-phenylindole, increase in number during the prolonged growth phase of the V. carteri gonidium. Microspectrofluorometry of fluorochrome-stained DNA in situ shows that plastid DNA increases exponentially throughout this phase. The continuous plastid DNA accumulation during gonidial growth appears to represent a prokaryote-like instead of a eukaryote-like control of DNA synthesis. Most somatic cells contain plastid DNA, and this does not increase in amount during colony growth and reproduction. Most sperm cells also contain plastid DNA, although approximately 5% of somatic cells and up to 20% of sperm cells have no discernable plastid DNA. This is the second group of organisms in which DNA-free plastids have been observed.     

Conserved Organization of γ-Aminobutyric AcidAReceptor Genes: Cloning and Analysis of the Chicken β4-Subunit Gene

A series of genomic clones containing DNA that encodes the chicken gamma-aminobutyric acidA (GABAA) receptor beta 4 subunit have been isolated. These have been restriction mapped and partially sequenced to determine the structural organization and the size of the beta 4-subunit gene. This gene, which comprises nine exons, spans more than 65 kb. The organization of the chicken GABAA receptor beta 4-subunit gene has been compared to that of the murine GABAA receptor delta-subunit gene and to those of the genes that encode other members of the ligand-gated ion-channel superfamily, namely muscle and neuronal nicotinic acetylcholine receptors (AChRs). Although the positions of the intron/exon boundaries of GABAA receptor subunit genes are seen to be highly conserved, there are significant differences between the genes that encode GABAA receptor and AChR subunits. These results are discussed in relation to the proposal that this superfamily of ligand-gated ion-channel receptor genes arose by duplication of an ancestral receptor gene.     

Sprunghafter Anstieg von Brutst?rungen bei H?hlenbrütern

Summary From 1986 onwards increasing numbers of Great Tits (Parus major) and Blue Tits (Parus caeruleus) were registered breeding on empty nests. In 1987 and 1988 up to 4% of all found sitting on nests did not lay any egg. The rate of breeding failures might be considerably higher because many individuals breeding on empty nests could have been overlooked by weekly checks of the nest boxes.     

Polyphosphoinositide mono- an diphosphoesterases of three subfractions of rat brain myelin

Phosphomonoesterase and diesterase that cleave phosphatidylinositol-4-phosphate (diphosphoinositide, DPI) and phosphatidylinositol-4,5-bisphosphate (triphosphoinositide, TPI) were detected in three subfractions of purified rat brain myelin, and some properties of the enzymes were studied. Monoesterase activity was stimulated by KCl, maximally at a concentration of 25 mM, and inhibited at KCl concentrations above 50 mM. Addition of boiled pH 5 supernatant of rat brain homogenate doubled the enzymic activity; EDTA was inhibitory. The specific activities were nearly equal in the low density, medium density, and heavy density myelin fractions but about 30% lower than in whole brain homogenate. The monophosphatase could be solubilized by extraction with 0.2% Triton X-100. The phosphodiesterase activity was inhibited by EDTA and EGTA and not stimulated by KCl or pH 5 supernatant. Specific activities were nearly equal in whole brain and myelin but were by about 60 percent elevated in the heavy density over the low density myelin fraction. These results show that the hydrolases operative in the fast turnover of the inositide phosphate groups are distributed over the entire myelin structure.     

Sequence complexity of poly(A) RNA fromPhysarum polycephalum

Summary Poly(A) RNA from S phase, G₂ phase and starved macroplasmodia of Physarum contain mRNA sequences which when translated in vitro, yield similar patterns of polypeptides after fluorography.Reassociation of nick-translated DNA (Cot) allows the isolation of highly labeled single copy DNA which, after saturation hybridization with poly(A) RNA, gives values of 23% for growth and 17% for starvation.Homologous cDNA/poly(A) RNA hybridization reactions (Rot) indicate that 22–28% of the genome is transcribed during growth and 12% during starvation and that about half of the cDNA reacts with 0.1% of the genome and could represent 50–80 RNA species, each present in about 1,000 copies per nucleus. Up to 25,000 different RNA species, 1–5 copies each per nucleus, are estimated to be present during growth, and about 15,000 during starvation. Heterologous cDNA/poly(A) RNA hybridization reactions (Rot) indicate that the RNA sequences in S and G₂ phase of the cell cycle are similar, with RNA sequences being more abundant in G₂ phase.During starvation about 25% of the sequences present during growth cannot be detected and those sequences present during growth have become diluted during starvation.     

Rapid Incorporation In Vivo of Intracerebrally Injected 32Pi into Polyphosphoinositides of Three Subfractions of Rat Brain Myelin

Abstract: At intervals ranging from 1 to 10 min after injection of ³²Pi into rat brain, myelin was prepared and separated into three subfractions: heavy, medium, and light. The radioactivity of total phospholipids and polyphospho-inositides (PPI) was then determined. There was rapid incorporation of ³²Pi into PPI, which contained 50–70% of the radioactivity among total brain lipids and more than 70% among myelin lipids. The myelin fraction had incorporated ³²Pi into total recovered PPI in the order of medium > heavy > light fraction: however, the order of relative specific radioactivities was heavy > light > medium. Labeling of the PPI precursors, phosphatidic acid (PA) and phos-phatidylinositol (PI), was considerably lower in the purified myelin than in total brain. The di- (DPI) and triphosphoinositides (TPI) in heavy myelin exchanged ³²Pi at rates 2 to 3 times faster than those in medium and light myelin. DPI of all subfractions of myelin exchanged much faster than TPI. The results show that the most active phosphate turnover of myelin PPI occurs in the heavy myelin fraction (probably largely consisting of myelin appurtenant regions). However, medium and light myelin (most probably representing the closely packed layers of myelin sheaths) also showed rapid turnover of PPI.     

MOLECULAR DELINEATION OF SPECIES AND SYNGENS IN VOLVOCACEAN GREEN ALGAE (CHLOROPHYTA)1

Two species of the colonial green flagellate family Volvocaceae are worldwide in distribution yet exhibit contrasting species structure. Geographically disparate isolates of Gonium pectorale Mueller can interbreed while isolates of Pandorina morum Bory behave quite differently. More than 20 sexually isolated subpopulations occur within this species; these have been termed “syngens” (sensu Sonneborn). Because prezygotic barriers to mating cause intersyngen pairings to fail, breeding analyses cannot be used to estimate genetic relatedness among the syngens of P. morum. DNA comparisons provide an alternative method of assessing genetic relatedness. We compared the nucleotide sequence of the internal transcribed spacer (ITS) region of the nuclear ribosomal repeat among clones of P. morum and of G. pectorale. Members of syngens of P. morum with distribution restricted to one small geographical area show great similarity. Likewise, members of any syngen of worldwide distribution show near uniformity, even those from different continents. However, the ITS sequence of each syngen differs from that of other syngens. In contrast, G. pectorale, which has an ITS region that is remarkably uniform throughout the world, appears to consist of a single syngen within North America and Europe by mating tests. The molecular data are in complete conformity with previous syngen assignment. Because the latter is based on mating affinity, with two complementary mating types per syngen, the evolution of new mating type pairs appears to be the basis of microevolution in these algae. We infer that either P. morum is a more ancient species than G. pectorale or that P. morum has a less stable genome. In either case, the biogeographic distribution of certain syngens may reflect climatological changes of the past.     

The Burden of Research on Trauma for Respondents: A Prospective and Comparative Study on Respondents Evaluations and Predictors

The possible burden of participating in trauma research is an important topic for Ethical Committees (EC''s), Review Boards (RB''s) and researchers. However, to what extent research on trauma is more burdensome than non-trauma research is unknown. Little is known about which factors explain respondents evaluations on the burden: to what extent are they trauma-related or dependent on other factors such as personality and how respondents evaluate research in general? Data of a large probability based multi-wave internet panel, with surveys on politics and values, personality and health in 2009 and 2011, and a survey on trauma in 2012 provided the unique opportunity to address these questions. Results among respondents confronted with these events in the past 2 years (N = 950) showed that questions on trauma were significantly and systematically evaluated as less pleasant (enjoyed less), more difficult, but also stimulated respondents to think about things more than almost all previous non-trauma surveys. Yet, the computed effect sizes indicated that the differences were (very) small and often meaningless. No differences were found between users and non-users of mental services, in contrast to posttraumatic stress symptoms. Evaluations of the burden of previous surveys in 2011 on politics and values, personality and health most strongly, systematically and independently predicted the burden of questions on trauma, and not posttraumatic stress symptoms, event-related coping self-efficacy and personality factors. For instance, multiple linear regression analyses showed that 30% of the variance of how (un)pleasant questions on trauma and life-events were evaluated, was explained by how (un)pleasant the 3 surveys in 2011 were evaluated, in contrast to posttraumatic stress symptoms (not significant) and coping self-efficacy (5%). Findings question why EC''s, RB''s and researchers should be more critical of the possible burden of trauma research than of the possible burden of other non-trauma research.     

Brewers’ spent grain liquor as a feedstock for lactate production with Lactobacillus delbrueckii subsp. lactis

Brewers’ spent grain (BSG) is a low‐cost by‐product of the brewing process. BSG liquor names the liquid components of BSG, mainly glucose, maltose, and long‐chain α‐1,4‐glycosidic bond glucose oligomers. These substances should be separated in existing BSG biorefineries, as they might lead to an increased formation of microbe‐inhibiting compounds in well‐established hydrothermal/enzymatic saccharification processes. In most cases, this liquid fraction is discarded. The present study presents for the first time an optimized process with BSG liquor for the purpose of producing bulk chemicals (e.g., lactate) in relevant concentrations. The process comprises the application of yeast extract, produced from own brewing processes, as the sole supplemented complex constituent in a simultaneous fermentation and saccharification process. Kinetic parameters for the final optimized process conditions with the organism Lactobacillus delbrueckii subsp. lactis were: maximum specific growth rate µ_max  =  0.47 h^?1, maximum lactate concentration c_Lac, max  =  79.06 g L^?1, process yield Y_PS  =  0.89 g_Lac g_Sugar^?1, lactate production rate q_P  =  4.18 g_Lac g_CDW^?1 h^?1, and productivity P _15 h  =  4.93 g_Lac L^?1 h^?1. BSG liquor, linked with yeast extract from Brewers’ yeast, can be a promising substrate for further bioprocess engineering tasks and contribute to a holistic and sustainable usage of Brewers’ spent grain.