TRANSMISSION AND SIGNIFICANCE OF B CHROMOSOMES IN ANTHURIUM WAROCQUEANUM

Somatic and meiotic chromosomes of one plant of Anthurium warocqueanum J. Moore and its selfed offspring were analyzed. The parent showed 2n = 30 + 3B in both somatic cells and pollen mother cells. The B chromosomes divided normally in somatic cells, but meiotic associations of Bs varied. Three configurations of three B chromosomes were observed at metaphase I of parent meiosis: one trivalent, one bivalent and one univalent, or three univalents. The number of B chromosomes in offspring ranged from 0 to 6, indicating their transmission from both male and female gametes. Offspring with two B chromosomes appeared in greatest frequency. It was hypothesized that both male and female gametes of the 3 B parent frequently contained one B chromosome through the normal distribution of the bivalent Bs at meiosis and the elimination of the univalent B chromosome due to lagging. Examination of pollen mother cells of offspring also revealed irregular behavior of B chromosomes. With a high number of B chromosomes, normal A chromosome bivalent formation seemed to be reduced. No phenotypic effects of B chromosomes were observed.     

Presence of carnitine acetyltransferase in peroxisomes and in mitochondria of oleic acid-grown Saccharomyces cerevisiae

Abstract Paracoccidiodes brasiliensis , the agent of paracoccidioidomycosis, when grown in a synthetic medium, expresses at the cell surface of both yeast and mycelial forms acidic glycoconjugates containing N -acetlyneuraminic acid units. Sialic acids were extracted using mild hydrolytic conditions, and were identified by thin-layer and gas chromatography, standard colorimetry, reaction with periodate-resorcinol and mass spectrometry. Their surface location was inferred from fluorescent-lectin ( Limulus polyphemus agglutinin) binding to whole cells abrogated by previous treatment with neuraminidase. Expression of sialic acids on virulent yeast forms of P. brasiliensis (3.7 × 10⁶ residues per cell) may inhibit fungal phagocytosis during early infection, when the immunological response is still being built up.     

Collapse of Peroxide-Scavenging Systems in Apple Flower-Buds Associated with Freezing Injury

Changes in the metabolic activities of peroxide-producing systemsand peroxide-scavenging systems after freezing and thawing inflower buds of the apple, Malus pumila Mill., were studied withspecial reference to freezing injury. In flower buds of the‘McIntosh’ apple that were frozen below lethal temperatures,the activity of NADH-Cyt c reductase (EC 1.6.99.3 [EC] ), one of theenzymes in the electron-transport chains that are related tothe peroxide-producing systems, decreased slightly, while thatof Cyt c oxidase (EC 1.9.3.1 [EC] ) hardly changed. By contrast, theactivities of glucose-6-phosphate dehydrogenase (EC 1.1.1.49 [EC] ),dehydroascorbate reductase (EC 1.8.5.1 [EC] ) and ascorbate peroxidase(EC 1.11.1.11 [EC] ), which are involved in the peroxide-scavengingsystems, decreased to very low levels. The activity of glyceraldehyde-3-phosphatedehydrogenase (EC 1.2.1.12 [EC] ) also decreased markedly. However,little change was observed in the activities of hexokinase (EC2.7.1.1 [EC] ), glucosephosphate isomerase (EC 5.3.1.9 [EC] ), glutathionereductase (EC 1.6.4.2 [EC] ) and glutathione peroxidase (EC 1.11.1.9 [EC] ).Examination of substrates involved in the peroxide-scavengingsystems revealed that the levels of glucose-6-phosphate andfructoses-phosphate decreased to approximately 10^–4 to10^–5 M and 10^–5 M, respectively, and the levelsof GSH decreased to about 10^–5 M or became barely detectable.A decrease in the levels of GSSG also occurred while levelsof ascorbate rose slightly. Similar results were observed withflower buds from ‘Starking Delicious’ and ‘Jonathan’apple trees. These results suggest that the freezing injury to apple flower-budsis closely related to the collapse of the peroxide-scavengingsystems that are coupled with the pentose phosphate cycle. Theresults also suggest that the dysfunction of these peroxide-scavengingsystems is caused by H₂O₂, which may be produced during freezingand thawing. (Received March 14, 1992; Accepted June 5, 1992)     

Detection of antibodies to Neospora caninum in cattle by enzyme-linked immunosorbent assay with truncated NcSRS2 expressed in Escherichia coli

The surface antigen 1-related sequence 2 of Neospora caninum (NcSRS2) is considered as an immunodominant antigen. In this study, the gene encoding truncated NcSRS2 (NcSRS2t) lacking an N-terminal signal peptide and C-terminal hydrophobic regions was expressed in Escherichia coli, and its diagnostic potential in an enzyme-linked immunosorbent assay (ELISA) was evaluated. ELISA could discriminate clearly between known N. caninum-positive and -negative sera from cattle. Field serum samples collected from cattle in Brazil were examined for the diagnosis of N. caninum infection using ELISA. Of the 197 samples analyzed, 64 (32.5%) samples were positive for antibodies to N. caninum. Of the 64 ELISA-positive samples, 58 (90.6%) were confirmed as positive by Western blot analysis with whole-parasite antigens. These results suggest that ELISA with recombinant NcSRS2t is an effective method for diagnosis of N. caninum infection in cattle.     

Release of ecdysteroid-phosphates from egg yolk granules and their dephosphorylation during early embryonic development in silkworm, Bombyx mori

Newly laid eggs of many insect species store maternal ecdysteroids as physiologically inactive phosphoric esters. In the silkworm Bombyx mori, we previously reported the presence of a specific enzyme, called ecdysteroid-phosphate phosphatase (EPPase), which catalyzes the dephosphorylation of ecdysteroid-phosphates to increase the amount of free ecdysteroids during early embryonic development. In this study, we demonstrated that (1) EPPase is found in the cytosol of yolk cells, (2) ecdysteroid-phosphates are localized in yolk granules, being bound to the yolk protein vitellin (Vn), and (3) Vn-bound ecdysteroid-phosphates are scarcely hydrolyzed by EPPase, although free ecdysteroid-phosphates are completely hydrolyzed by EPPase. Thus, we investigated the mechanism by which ecdysteroid-phosphates dissociate from the Vn-ecdysteroid-phosphate complex, and indicated that the acidification of yolk granules causes the dissociation of ecdysteroid-phosphates from the Vn-ecdysteroid-phosphate complex and thereby ecdysteroid-phosphates are released from yolk granules into the cytosol. Indeed, the presence of vacuolar-type proton-translocating ATPase in the membrane fraction of yolk granules was also verified by Western blot analysis. Our experiments revealed that Vn functions as a reservoir of maternal ovarian ecdysteroid-phosphates as well as a nutritional source during embryonic development. This is the first report showing the biochemical mechanism by which maternal Vn-bound ecdysteroid-phosphates function during early embryonic development.     

Recent progress towards the application of hyperthermophiles and their enzymes

The discovery of extremophiles has drastically changed our understanding towards the diversity of life itself and the conditions under which it can be sustained. Extremophiles have evolved to withstand and multiply under the extremes of temperature, pressure, pH and salinity. Hyperthermophiles are the group that have adapted to high temperature; many have been found to grow at temperatures above the boiling point of water. This review focuses on recent advances in application-based research on hyperthermophiles and their thermostable enzymes.     

A possible role of 20-hydroxyecdysone in embryonic development of the silkworm Bombyx mori

It has been well established that eggs of insects, including those of the silkworm Bombyx mori, contain various ecdysteroids and the amounts of these ecdysteroids fluctuate during embryonic development. In order to know the function of egg ecdysteroids in embryonic development of B. mori, we examined the biological activities of various egg ecdysteroids by in vitro ligand-binding assay and bioassay using B. mori eggs. First, using the ecdysteroid receptor of B. mori (BmEcR-B1/BmUSP heterodimer) prepared by yeast and Escherichia coli expression systems, the interaction between the ecdysteroid receptor and various egg ecdysteroids of B. mori was analyzed. The relative binding affinities of egg ecdysteroids to the BmEcR-B1/BmUSP heterodimer decreased in the order of 20-hydroxyecdysone > 2-deoxy-20-hydroxyecdysone > 22-deoxy-20-hydroxyecdysone > ecdysone > 2-deoxyecdysone > ecdysone 22-phosphate. Next, several egg ecdysteroids of B. mori were injected into the prospective diapause eggs, which show a very low level of free ecdysteroids at the onset of embryonic diapause (gastrula stage). Approximately 7% of them (P < 0.002, chi(2)-test) developed beyond the gastrula stage without entering diapause by the injection of 20-hydroxyecdysone (25 ng/egg). In contrast, the injection of other ecdysteroids was not effective in inducing embryonic development. These results suggest that 20-hydroxyecdysone, via the ecdysteroid receptor, is responsible for the developmental difference between diapause and non-diapause in B. mori embryos. Furthermore, it was suggested that continuous supply of 20-hydroxyecdysone may be required to induce embryonic development.     

Role of dietary phosphorus in the progression of renal failure

Dietary phosphorus is thought to be a factor that impairs the residual renal function in patients with chronic renal failure. To determine the effect of dietary phosphorus on the prognosis of chronic renal failure, low-phosphorus milk was prepared from normal cow's milk using boehmite, a synthetic phosphate-ion absorbent. Regular diet, normal cow's milk, and low-phosphorus milk were then given to 5/6-nephrectomized rats and the serum levels of inorganic phosphorus, calcium, creatinine, and blood urine nitrogen in the rats in each group were compared. The serum levels of inorganic phosphorus and calcium were not different among the groups, despite a significant difference in phosphorus intakes. On the other hand, serum levels of creatinine (Cr) and blood urine nitrogen (BUN) in the rats fed low-phosphorus milk were significantly lower (Cr, 0.54+/-0.054mg/dl; BUN, 29.2+/-3.90mg/dl) than those in the rats fed a regular diet (Cr, 0.64+/-0.057mg/dl; BUN, 37.4+/-3.55mg/dl) or normal milk (Cr, 0.61+/-0.040mg/dl; BUN, 34.5+/-3.59mg/dl). No beneficial effect of protein restriction was observed when residual renal functions in rats fed a regular diet and those fed normal milk were compared. The results suggest that dietary phosphorus plays a major role in the progression of renal failure.     

A Simple Method for Differentiating Complicated Parapneumonic Effusion/Empyema from Parapneumonic Effusion Using the Split Pleura Sign and the Amount of Pleural Effusion on Thoracic CT

Background

Pleural separation, the “split pleura” sign, has been reported in patients with empyema. However, the diagnostic yield of the split pleura sign for complicated parapneumonic effusion (CPPE)/empyema and its utility for differentiating CPPE/empyema from parapneumonic effusion (PPE) remains unclear. This differentiation is important because CPPE/empyema patients need thoracic drainage. In this regard, the aim of this study was to develop a simple method to distinguish CPPE/empyema from PPE using computed tomography (CT) focusing on the split pleura sign, fluid attenuation values (HU: Hounsfield units), and amount of fluid collection measured on thoracic CT prior to diagnostic thoracentesis.

Methods

A total of 83 consecutive patients who underwent chest CT and were diagnosed with CPPE (n=18)/empyema (n=18) or PPE (n=47) based on the diagnostic thoracentesis were retrospectively analyzed.

Results

On univariate analysis, the split pleura sign (odds ratio (OR), 12.1; p<0.001), total amount of pleural effusion (≥30 mm) (OR, 6.13; p<0.001), HU value≥10 (OR, 5.94; p=0.001), and the presence of septum (OR, 6.43; p=0.018), atelectasis (OR, 6.83; p=0.002), or air (OR, 9.90; p=0.002) in pleural fluid were significantly higher in the CPPE/empyema group than in the PPE group. On multivariate analysis, only the split pleura sign (hazard ratio (HR), 6.70; 95% confidence interval (CI), 1.91-23.5; p=0.003) and total amount of pleural effusion (≥30 mm) on thoracic CT (HR, 7.48; 95%CI, 1.76-31.8; p=0.006) were risk factors for empyema. Sensitivity, specificity, positive predictive value, and negative predictive value of the presence of both split pleura sign and total amount of pleural effusion (≥30 mm) on thoracic CT for CPPE/empyema were 79.4%, 80.9%, 75%, and 84.4%, respectively, with an area under the curve of 0.801 on receiver operating characteristic curve analysis.

Conclusion

This study showed a high diagnostic yield of the split pleura sign and total amount of pleural fluid (≥30 mm) on thoracic CT that is useful and simple for discriminating between CPPE/empyema and PPE prior to diagnostic thoracentesis.