Animal community structure as a function of stream size

The species-area relationship of the island biogeography theory was calculated for macroinvertebrates in 22 coastal, adjacent streams. A z-value of 0.19 was obtained. The low z-value was probably a consequence of the short distances between streams as well as high dispersal rates. In addition, a cluster analysis based on the dissimilarity of species assemblages showed that stream size was of prime importance in categorizing the streams. To a smaller extent water quality affected the community structure in the streams.     

Spore production ofPenicillium roqueforti in fermentors filled with buckwheat seeds: batch and semi-continuous cultivation

Summary The behaviour of a drum fermentor and a column fermentor during the sporulation ofPenicillium roqueforti on buckwheat seeds is presented. The main problem encountered during the course of a cultivation is the free water released (about 0.1 ml/g dry matter) which must be removed from the medium. The rotation of the drum fermentor may disturb the growth and the sporulation. The column fermentor thus represents the best way to perform batch cultivation of the fungus: 10⁹ external spores/g dry matter are obtained.Semi-continous cultivation, with sequential emptying and filling, is performed in 1-liter bottles. This kind of cultivation may give a maximal average productivity close to 9.2·10⁶ external spores/g dry matter per hour. A drum fermentor, rotading only when emptying and filling, could represent an alternative to perform this kind of cultivation.     

Distribution of intrapleural and intravenous Corynebacterium parvum in humans; 99mTc−, and 131I-labeled bacteria

Summary The distribution of Corynebacterium parvum labeled with ¹³¹iodine or ^99mtechnetium was studied in 17 patients with bronchogenic carcinoma. The labeled bacteria were given intravenously or intrapleurally and monitored by whole-body gamma tracking and samples of blood and urine. Even though the rate of physical decay is quite different for ¹³¹iodine and ^99mtechnetium, the tracking time of labeled bacteria was limited to 24 h after injection for both radioactive isotopes. Technetium labeling was preferred because of greater imaging resolution and less radiation dose to the patient. Following intravenous administration, labeled C. parvum was found predominantly in the liver and spleen, and in a lesser amount in the lung. Radioactivity was confined to the pleural cavity after intrapleural injection. These results suggest the combined intravenous and intrapleural route of adjuvant immunosupportive agents such as C. parvum for operable lung cancer patients.     

Correlation between automated DNA ploidy measurements of Hürthle-cell tumors and their histopathologic and clinical features

The treatment of Hürthle-cell tumors of the thyroid is controversial because of their rarity and the inconsistent histopathologic criteria for their diagnosis. In order to obtain more objective criteria for the management of Hürthle-cell tumors, the nuclear DNA content of cells from 20 cases was measured with the MicroTICAS system and the correlation between the DNA distribution patterns and the clinical and histopathologic findings was evaluated. Three main DNA patterns were found: euploid, polyploid and aneuploid. The euploid or polyploid Hürthle-cell tumors came from patients who did not develop distant metastases or recurrence whereas the aneuploid variants came from patients who died of their disease and/or developed distant metastases and recurrence. Various correlation analyses were performed between DNA ploidy and age, sex, size of tumor, growth pattern, pleomorphism, invasion and metastases. Our data suggests that an aneuploid DNA pattern or one with a large percentage of aneuploid nuclei with DNA content exceeding 5N may predict eventual metastases or recurrence from Hürthle-cell tumor.     

Regulation of calcium accumulation and efflux from platelet vesicles: Possible role for cyclic-AMP-dependent phosphorylation and calmodulin

Calcium-accumulating vesicles were isolated by differential centrifugation of sonicated platelets. Such vesicles exhibit a $\text{(Ca}{}^{\mathrm{2+}}\text{+ Mg}{}^{\mathrm{2+}}\text{)-ATPase}$ activity of about 10 nmol (min·mg)^?1 and an ATP-dependent Ca²⁺ uptake of about 10 nmol (min·mg)^?1. When incubated in the presence of Mg[γ-³²P]ATP, the pump is phosphorylated and the acyl phosphate bond is sensitive to hydroxylamine. The [³²P]phosphate-labeled Ca²⁺ pump exhibits a subunit molecular weight of 120 000 when analyzed by lithium dodecyl sulfate-polyacrylamide gel electrophoresis. Platelet calcium-accumulating vesicles contain a 23 kDa membrane protein that is phosphorylatable by the catalytic subunit of cAMP-dependent protein kinase but not by protein kinase C. This phosphate acceptor is not phosphorylated when the vesicles are incubated in the presence of either Ca²⁺ or Ca²⁺ plus calmodulin. The latter protein is bound to the vesicles and represents 0.5% of the proteins present in the membrane fraction. Binding of ¹²⁵I-labeled calmodulin to this membrane fraction was of high affinity (16 nM), and the use of an overlay technique revealed four major calmodulin-binding proteins in the platelet cytosol ($\text{M}{}_{\mathrm{r}}\text{= 94 000, 87 000, 60 000 and 43 000}$). Some minor calmodulin-binding proteins were enriched in the membrane fractions ($\text{M}{}_{\mathrm{r}}\text{= 69 000, 57 000, 39 000 and 37 000}$). When the vesicles are phosphorylated in the presence of MgATP and of the catalytic subunit of cAMP-dependent protein kinase, the rate of Ca²⁺ uptake is essentially unaltered, while the Ca²⁺ capacity is diminished as a consequence of a doubling in the rate of Ca²⁺ efflux. Therefore, the inhibitory effect of cAMP on platelet function cannot be explained in such simple terms as an increased rate of Ca²⁺ removal from the cytosol. Calmodulin, on the other hand, was observed to have no effect on the initial rate of calcium efflux when added either in the absence or in the presence of the catalytic subunit of the cyclic AMP-dependent protein kinase, nor did the addition of 0.5 μM calmodulin result in increased levels of vesicle phosphorylation.     

Application of Response Surface Methodology to Evaluation of Bioconversion Experimental Conditions

Using Candida tenuis, a yeast isolated from the digestive tube of the larva of Phoracantha semipunctata (Cerambycidae, Coleoptera), we were able to demonstrate the bioconversion of citronellal to citronellol. Response surface methodology was used to achieve the optimization of the experimental conditions for that bioconversion process. To study the proposed second-order polynomial model, we used a central composite experimental design with multiple linear regression to estimate the model coefficients of the five selected factors believed to influence the bioconversion process. Only four were demonstrated to be predominant: the incubation pH, temperature, time, and the amount of substrate. The best reduction yields (close to 90%) were obtained with alkaline pH conditions (pH 7.5), a low temperature (25°C), a small amount of substrate (15 μl), and short incubation time (16 h). This methodology was very efficient: only 36 experiments were necessary to assess these conditions, and model adequacy was very satisfactory as the coefficient of determination was 0.9411.     

Refined 2 A X-ray crystal structure of porcine pancreatic kallikrein A, a specific trypsin-like serine proteinase. Crystallization, structure determination, crystallographic refinement, structure and its comparison with bovine trypsin

Porcine pancreas kallikrein A has been crystallized in the presence of the small inhibitor benzamidine, yielding tetragonal crystals of space group P4₁2₁2 containing two molecules per asymmetric unit. X-ray data up to 2·05 Å resolution have been collected using normal rotation anode as well as synchrotron radiation. The crystal structure of benzamidine-kallikrein has been determined using multiple isomorphous replacement techniques, and has subsequently been refined to a crystallographic R-value of 0·220 by applying a diagonal matrix least-squares energy constraint refinement procedure.Both crystallographically independent kallikrein molecules 1 and 2 are related by a non-integral screw axis and form open, heterologous “dimer” structures. The root-mean-square deviation of both molecules is 0·37 Å for all main-chain atoms. This value is above the estimated mean positional error of about 0·2 Å and reflects some significant conformational differences, especially at surface loops. The binding site of molecule 1 in the asymmetric unit is in contact with residues of molecule 2, whereas the binding site of the latter is free and accessible to the solvent. In both molecules the characteristic “kallikrein loop”, where the peptide chain of kallikrein A is cleaved, is only partially traceable. The carbohydrate attached to Asn95 in this loop, although detectable chemically, is not defined.A comparison of the refined structures of porcine kallikrein and bovine trypsin indicates spatial homology for these enzymes. The root-mean-square difference is 0·68 Å if we compare only main-chain atoms of internal segments. Remarkably large deviations are found in some external loops most of which surround the binding site and form a more compact rampart around it in kallikrein than in trypsin. This feature might explain the strongly reduced activity and accessibility of kallikrein towards large protein substrates and inhibitors (e.g. as shown by the model-building experiments on inhibitor complexes reported by Chen &; Bode. 1983).The conformation of the active site residues is very similar in both enzymes. Tyr99 of kallikrein, which is a leucyl residue in trypsin, protrudes into the binding site and interferes with the binding of peptide substrates (Chen &; Bode. 1983). The kallikrein specificity pocket is significantly enlarged compared with trypsin due to a longer peptide segment, 217 to 220, and to the unique outwards orientation of the carbonyl group of cis-Pro219. Further, the side-chain of Ser226 in porcine kallikrein, which is a glycyl residue in trypsin, partially covers Asp 189 at the bottom of the pocket. These features considerably affect the binding geometry and strength of binding of benzamidine.     

High-resolution color video cytophotometry

Comparison was made between cytophotometric measurements obtained using two data acquisition systems, one a microphotometer and the other a rapid video camera system, to ascertain whether the degradation of data with the faster video acquisition system still results in recorded images of sufficient quality to permit computer discrimination between cells of very similar appearance. Normal-appearing intermediate cells from cases with normal cytology and those from patients with dysplasia or malignant disease, as well as the subvisual markers within these cells that have rendered them capable of cytophotometric discrimination, were used for the study. Comparison of the data recorded by the two systems indicates that the diagnostic information is preserved in the change-over to a full-field, video-rate scanning system, with differences in the data caused primarily by differences in the spectral response of the two systems. This was reflected in the substantial differences observed in the color-related features and the lesser differences seen in the textural features, while the morphometric features (outline and shape) were virtually unaffected. The differences were primarily expressed on a cell-to-cell basis; in sets of about 300 cells, which would be used in patient-to-patient comparisons, the feature values showed remarkable consistency between the two systems.