Effects of microbial floras on the distributions of five domestic Drosophila species across fruit resources

Summary The distributions of five Drosophila species and four components of the microflora have been compared across a total of 48 traps baited with four different fruit and vegetable substrates in two domestic compost heaps in Canberra (Australia). Large and consistent differences are found, both among the Drosophila and among the microbial classes, in their distributions across traps baited with different substrates. Moreover the distribution of each Drosophila species shows a unique set of strong associations with the microbial distributions. Thus the distributions of both D. simulans and D. melanogaster are found to be strongly negatively correlated with the abundance of bacteria while D. simulans is also strongly positively correlated with the titre of fermenter yeasts. D. immigrans is strongly positively correlated both with bacteria and with non-fermenter yeasts. D. hydei is positively correlated with nonfermentery yeasts and D. busckii is negatively correlated with fermenter yeasts. Moulds are the only microbial class not consistently associated with the distribution of any of the Drosophila species. The correlations with the other microbial classes are sufficient to explain the majority of the abundance differences of the Drosophila species among the trap types. It is therefore proposed that the clear partitioning of the fruit resources by the Drosophila is due to their differing primary interactions with the microflora.     

Improved Cultivation Systems for Isolation of the Colorado Potato Beetle Spiroplasma

In North America, the Colorado potato beetle, Leptinotarsa decemlineata, is often infected with the host-specific, gut-inhabiting Colorado potato beetle spiroplasma (CPBS). CPBS is apparently a commensal, but it may be useful in biocontrol if it can be transformed to express an insect-lethal gene. Difficulty in cultivating the organism, however, has hindered the development of a suitable transformation system. In this study, we eliminated the need for coculturing CPBS with insect cells. CPBS was reliably isolated with the BBL Anaerobic GasPak Jar system (low redox, enhanced CO(inf2)), which was easier to use and less expensive than insect cell coculture methods. A further advantage is a reduction in contaminating insect cell components. Use of anaerobiosis should facilitate early-passage screening of isolates for extrachromosomal elements, for use in gene vector constructs. The unique spiral (decreasing amplitude of coils) morphology of CPBS was preserved by anaerobiosis. The use of low-pH (6.0 to 6.5) media allowed aerobic adaptation of CPBS to M1D and SP-4 broth media. These formulations permitted the first cultivation of CPBS on solid media, an accomplishment that will simplify the selection of molecular transformants. Potato beetles collected at four sites in Poland yielded CPBS strains similar to those previously obtained from populations in North America.     

Effect of Hyperthyroidism On Haemopoietic Stem Cell Kinetics In Mice

Changes in the pool of haemopoietic colony-forming units (CFUs) of bone marrow and spleen were studied in experiments with mice fed dried thyroid gland (TH) for 21 days, and during the 13 days that followed feeding. After HU treatment, the number of CFUs in DNA synthesis was estimated. As early as the second day of TH treatment, the pool of CFUs is gradually increased, leading to an increase in the total number of splenic and bone marrow CFUs persisting after TH treatment for the period examined. Simultaneously, the numbers of nucleated cells in the bone marrow and spleen are increased. During TH feeding and following its termination, the total number of erythrocytes and the haematocrit values did not change significantly, whereas an increased number of leucocytes was observed in the peripheral blood after TH treatment. Elevation of the proliferative activity of CFUs occurred early in the period of TH treatment, with the maximum attained by end of the first week of TH feeding. This suggests a rapid response of the haemopoietic stem cell compartment to the administration of TH hormones. the participation of humoral factors controlling CFUs compartments in the mechanism of the stimulatory effect of TH hormones on haemopoietic stem cells is discussed.     

Insulin secretion from a continuously subcultivable isolate derived from foetal bovine pancreata beta cells. I. Monolayer cultures.

Monolayer cultures have been derived from bovine embryonic pancreatic cells grown in medium CMRL-1969 supplemented with foetal calf serum. The isolate has been subcultivated up to 10 population doublings. Insulin secretion from the cells into the culture medium declined with increasing passages. Of several insulin secretagogues, glucagon was found to be effective in potentiating insulin release from the cultivated cells into the medium. Insulin secretion rose to approximately 600 μU/culture/day in the presence of glucagon as compared to an average of 10 μU/culture/day in the control. This may be the first demonstration of a beta cell line developed from bovine embryonic pancreas.     

Intratumor heterogeneity of biomarker expression in breast carcinomas

Small biopsy samples are used increasingly to assess the biomarker expression for prognostic information and for monitoring therapeutic responses prior to and during neoadjuvant therapy. The issue of intratumor heterogeneity of expression of biomarkers, however, has raised questions about the validity of the assessment of biomarker expression based on limited tissue samples. We examined immunohistochemically the expression of HER-2neu (p185^erbB-2), epidermal growth factor receptor (EGFR), Bcl-2, p53, and proliferating cell nuclear antigen (PCNA) in 30 breast carcinomas using archived, paraffin embedded tissue and determined the extent of intratumor heterogeneity. Each section was divided into four randomly oriented discrete regions, each containing a portion of the infiltrating carcinoma. For each tumor, the entire lesion and four regions were analyzed for the expression of these markers. Scores of both membrane and cytoplasmic staining of HER-2neu and EGFR, scores of cytoplasmic staining of Bcl-2, and scores of nuclear staining of both p53 and PCNA were recorded. The intensity of staining and the proportion of immunostained cells were determined. A semiquantitative immunoscore was calculated by determining the sum of the products of the intensity and corresponding proportion of stained tumor cells. We analyzed both invasive (IDC) and in situ (DCIS) carcinomas. The Wilcoxon signed-rank test was used for paired comparisons between overall and regional immunoscores and between overall and regional percentages of stained cells. Spearman's correlation coefficients were used to assess the level of agreement of overall biomarker expression with each of the regions. Generalized linear models were used to assess overall and pair-wise differences in the absolute values of percent changes between overall and regional expression of biomarkers. For IDCs, there were no statistically significant differences in the expression of the biomarkers in terms of either the percentage of cells staining or the immunoscores when comparing the entire tumor with each region except for the lower EGFR expression of arbitrarily selected region 1 and lower p53 expression of region 1 compared to that of the entire tumor section. For DCIS, there were no statistically significant differences in the expression of the biomarkers between the entire tumor and each region except in PCNA of region 2 compared to that of entire tumor section. Positive correlation of immunoscores was observed between the entire tumor and each region as well as across all four regions for IDC. Similar observations were noted with DCIS except for HER-2neu and PCNA. No statistically significant differences were observed in the absolute values of percent changes of biomarker expression between overall and the four regions for both DCIS and IDC. Therefore, no significant intratumor heterogeneity in the expression of HER-2neu, Bcl-2, and PCNA was observed in IDC. Minor regional variations were observed for EGFR and p53 in IDC. Similarly, no significant regional variation in the expression of markers was observed in DCIS except for PCNA.     

Direct Evaluation of Vapour-Liquid Equilibria of Mixtures by Molecular Dynamics Using Gibbs-Duhem Integration

Abstract

We present an extension of the Gibbs-Duhem integration method that permits direct evaluation of vapour-liquid equilibria of mixtures by molecular dynamics. The Gibbs-Duhem integration combines the best elements of the Gibbs ensemble Monte Carlo technique and thermodynamic integration. Given conditions of coexistence of pure substances, simultaneous but independent molecular dynamics simulations of each phase at constant number of particles, constant pressure, constant temperature and constant fugacity fraction of species 2 are carried out in succession along coexistence lines. In each simulation, the coexistence pressure is adjusted to satisfy the Clapeyron-type equation. The Clapeyron-type equation is a first-order nonlinear differential equation that prescribes how the pressure must change with the fugacity fraction of species 2 to maintain coexistence at constant temperature. The Clapeyron-type equation is solved by the predictor-corrector method. Running averages of mole fraction and compressibility factor for the two phases are used to evaluate the right-hand side of the Clapeyron-type equation. The Gibbs-Duhem integration method is applied to three prototypes of binary mixtures of the two-centre Lennard-Jones fluid having various elongations. The starting points on the coexistence curve were taken from published data.     

Pretreatment with granulocyte colony-stimulating factor reduces myelopoiesis in irradiated mice

The purpose of this study was to investigate effects of the treatment prior to irradiation with granulocyte colony-stimulating factor (G-CSF) on hematopoiesis in B10CBAF1 mice exposed to a sublethal dose of 6.5 Gy of 60Co gamma radiation. G-CSF was administered in a 4-day regimen (3 microg/day); irradiation followed 3 h after the last injection of G-CSF. Such a treatment was found to stimulate granulopoiesis, as shown by increased counts of granulocyte-macrophage progenitor cells (GM-CFC) and of granulocytic cells in the femoral marrow and spleen at the time of irradiation. However, postirradiation counts of GM-CFC and granulocytic cells in the marrow of mice pretreated with G-CSF were reduced up to day 18 after irradiation. Interestingly, the D0 values for marrow GM-CFC determined 1 h after in vivo irradiation were 1.98 Gy for controls and 2.47 Gy for mice pretreated with G-CSF, indicating a decreased radiosensitivity of these cells after drug treatment. The inhibitory effects of the pretreatment with G-CSF on the postirradiation granulopoiesis could be attributed to the phenomenon of "rebound quiescence" which can occur after cessation of the treatment with growth factors. Postirradiation recovery of erythropoiesis in the spleen of mice pretreated with G-CSF exhibited a dramatic increase and compensated for the decreased erythropoiesis in the marrow at the time of irradiation. This complexity of the hematopoietic response should be taken into account when administering G-CSF in preirradiation regimens.     

Esterases as a marker for growth of BY-2 tobacco cells and early somatic embryos of the Norway spruce

Growth is one of the basic properties of biological systems. The methods which are commonly used for the determination of growth are usually difficult and not very accurate. In the present work we decided to use esterase activity as a growth marker in tobacco suspension culture (BY-2 line) and in early somatic embryos of Norway spruce (clone 2/32) grown on a semi-solid medium. Esterase activity correlates well with the classical growth characteristics of BY-2 and spruce early somatic embryos. Determination of esterase activity is based on spectrophotometric and spectrofluorimetric detection of reaction products, which arise from the enzymatic hydrolysis of two substrates (p -nitrophenyl acetate and fluorescein diacetate) by esterase. The spectrophotometric method enabled us to detect approximately 10⁴ BY-2 cells and 25 spruce embryos whereas the more sensitive spectrofluorimetric method allowed us to detect approximately 800 BY-2 cells and 5 early somatic embryos of Norway spruce.