Microtubule formation on the nuclear surface during meiosis inAcetabularia acetabulum

Summary Microtubules (MT) are a feature of all eukaryotic cells. However, they have not been observed in the cytoplasm of the vegetative phase ofAcetabularia acetabulum. Previous investigators have reported that, in the propagative phase, MTs function as anchors in the transport of secondary nuclei to the cap. They also form elaborate arrays around nuclei during cyst formation. The life history ofA. acetabulum is marked by changes in chromatin, the nucleolus, and the perinuclear cytoplasm. In this study light microscopical features of the nucleolus and changes in chromatin, labelled with anti-histon antibodies, were used to define the developmental stages. Anti-tubulin antibodies have been used to trace the origin and development of MTs, MTs are formed on the surface of the primary nucleus. They are organized first into short thick sticks and then later elongate into thinner strands which enclose the nucleus in a dense network. Following these events on the surface of the nucleus, the spindle develops inside the nuclear membrane which remains intact throughout the mitotic division.     

PRESENCE OF PHYCOERYTHRIN IN TWO STRAINS OF PROCHLOROCOCCUS (CYANOBACTERIA) ISOLATED FROM THE SUBTROPICAL NORTH PACIFIC OCEAN

Prochlorococcus is a ubiquitous marine oxyphotobacterium characterized by the presence of DV-chl a and b . In addition, the type strain Prochlorococcus marinus Chisholm et al. CCMP 1375 (or SS120), an isolate from the Sargasso Sea, contains low levels of an unusual phycoerythrin. Until now, it has been unclear if phycoerythrin occurs randomly within this systematic group and if the molecular characteristics of this phycoerythrin are restricted to this single strain. Here, we show that two additional Prochlorococcus strains from the Pacific Ocean also contain similar low levels of phycoerythrin. DNA sequence and phylogenetic analyses demonstrated that this phycoerythrin is very similar to the phycoerythrin of P. marinus SS120 and differs from the classic cyanobacterial phycoerythrins. In contrast, a third isolate from the Arabian Sea lacks phycoerythrin. Based on the DV-chl b:a ratio and 16S rRNA sequence data, we classify the two Pacific phycoerythrin-containing isolates as low-light-adapted strains and the Arabian Sea isolate as a high-light-adapted strain. Thus, we provide further evidence to link the physiology of an individual genotype and the presence or absence of functional phycoerythrin genes within the genus Prochlorococcus .     

Physiological MR signal variations within the brain at 3 T.

The echoplanar technique in magnetic resonance (MR) imaging allows the acquisition of a series of images from a selected slice with a temporal resolution of 10/s. Simultaneous recording of physiological information on pulse and respiration allows correlation of the MR signal intensity with physiological signals, which can be obtained for each pixel examined. Such correlations can be found within the cerebrospinal fluid (CSF) spaces and within vessels if a flow-sensitive MR measurement technique is used. The use of an MR scanner with a field strength of 3 T improves the signal/noise ratio, but there is a stronger signal decay due to local magnetic inhomogeneities. This study shows that 3-T systems can be used for correlation of MR and physiological signals and that clear differentiation between signals from CSF and from vessels can be obtained due to their strongly different signal decays.     

Wide distribution of the cysteine string proteins in Drosophila tissues revealed by targeted mutagenesis

The “cysteine string protein” (CSP) genes of higher eukaryotes code for a novel family of proteins characterized by a “J” domain and an unusual cysteine-rich region. Previous studies had localized the proteins in neuropil and synaptic terminals of larval and adult Drosophila and linked the temperature-sensitive paralysis of the mutants described here to conditional failure of synaptic transmission. We now use the null mutants as negative controls in order to reliably detect even low concentrations of CSPs by immunohistochemistry, employing three monoclonal antibodies. In wild-type flies high levels of cysteine string proteins are found not only in apparently all synaptic terminals of the embryonic, larval, and adult nervous systems, but also in the “tall cells” of the cardia, in the follicle cells of the ovary, in specific structures of the female spermatheca, and in the male testis and ejaculatory bulb. In addition, low levels of CSPs appear to be present in all tissues examined, including neuronal perikarya, axons, muscles, Malpighian tubules, and salivary glands. Western blots of isolated tissues demonstrate that of the four isoforms expressed in heads only the largest is found in non-neural organs. The wide expression of CSPs suggests that at least some of the various phenotypes of the null mutants observed at permissive temperatures, such as delayed development, short adult lifespan, modified electroretinogram, and optomotor behavior, may be caused by the lack of CSPs outside synaptic terminals.     

Renal Excretion of N4-Acetyl Sulphanilamide and N4-Acetyl Sulphadimidine in Goats

The renal excretion of N4-acetyl sulphanilamide and N4-acetyl sulphadimidine was studied in 19 experiments with 6 goats during continuous intravenous administration of the 2 sulphonamide derivatives. Deacetylation of both compounds takes place to a small extent only. Further it is shown that both sulphonamide derivatives are bound to plasma proteins to a greater extent than sulphanilamide and sulphadimidine. The excretion of the N4-acetylated sulphonamides is compared with the renal excretion of creatinine. The non-protein-bound fraction of the 2 N4-acetylated sulphonamides is excreted by filtration and active tubular secretion. The renal clearances of the acetyl derivatives are higher than those of the parent compounds.     

Skeleton binding protein-1-mediated parasite sequestration inhibits spontaneous resolution of malaria-associated acute respiratory distress syndrome

Malaria is a hazardous disease caused by Plasmodium parasites and often results in lethal complications, including malaria-associated acute respiratory distress syndrome (MA-ARDS). Parasite sequestration in the microvasculature is often observed, but its role in malaria pathogenesis and complications is still incompletely understood. We used skeleton binding protein-1 (SBP-1) KO parasites to study the role of sequestration in experimental MA-ARDS. The sequestration-deficiency of these SBP-1 KO parasites was confirmed with bioluminescence imaging and by measuring parasite accumulation in the lungs with RT-qPCR. The SBP-1 KO parasites induced similar lung pathology in the early stage of experimental MA-ARDS compared to wildtype (WT) parasites. Strikingly, the lung pathology resolved subsequently in more than 60% of the SBP-1 KO infected mice, resulting in prolonged survival despite the continuous presence of the parasite. This spontaneous disease resolution was associated with decreased inflammatory cytokine expression measured by RT-qPCR and lower expression of cytotoxic markers in pathogenic CD8⁺ T cells in the lungs of SBP-1 KO infected mice. These data suggest that SBP-1-mediated parasite sequestration and subsequent high parasite load are not essential for the development of experimental MA-ARDS but inhibit the resolution of the disease.     

Choline acetyltransferase-like immunoreactivity in the brain of Drosophila melanogaster

Summary Using a monoclonal antibody selective for the acetylcholine (ACh)-synthesizing enzyme choline acetyltransferase (ChAT) of Drosophila melanogaster we find ChAT-like immunoreactivity in specific synaptic regions throughout the brain of Drosophila melanogaster apart from the lobes and the peduncle of the mushroom body and most of the first visual neuropile (lamina). Several anatomically well-defined central brain structures exhibit particularly strong binding. Characteristic differential staining patterns are observed for each of the four neuromeres of the optic lobes. Cell bodies appear not to bind this antibody. The prominent features of the distribution of ChAT-like immunoreactivity are paralleled by the distribution of acetylcholine hydrolyzing enzymatic activity as revealed by histochemical staining for acetylcholine esterase (AChE). These results are discussed in comparison with published data on enzyme distribution, choline uptake and ACh receptor binding in the nervous system of Drosophila melanogaster.     

Multiple-line cross QTL mapping for biomass yield and plant height in triticale (× Triticosecale Wittmack)

Key message

QTL mapping in multiple families identifies trait-specific and pleiotropic QTL for biomass yield and plant height in triticale.

Abstract

Triticale shows a broad genetic variation for biomass yield which is of interest for a range of purposes, including bioenergy. Plant height is a major contributor to biomass yield and in this study, we investigated the genetic architecture underlying biomass yield and plant height by multiple-line cross QTL mapping. We employed 647 doubled haploid lines from four mapping populations that have been evaluated in four environments and genotyped with 1710 DArT markers. Twelve QTL were identified for plant height and nine for biomass yield which cross-validated explained 59.6 and 38.2 % of the genotypic variance, respectively. A major QTL for both traits was identified on chromosome 5R which likely corresponds to the dominant dwarfing gene Ddw1. In addition, we detected epistatic QTL for plant height and biomass yield which, however, contributed only little to the genetic architecture of the traits. In conclusion, our results demonstrate the potential of genomic approaches for a knowledge-based improvement of biomass yield in triticale.