Determination of monod kinetic coefficients for volatile hydrophobic organic compounds

A new procedure is presented to determine Monod kinetic coefficients and the microbial yield coefficient for volatile hydrophobic compounds such as phenanthrene. Batch experiments were conducted with a mixed culture capable of degrading phenanthrene. The phenanthrene disappearance and carbon dioxide production were monitored with time. A maximum likelihood estimator was formulated to fit the set of equations that describe the system to the measured data. The model takes into account a number of processes such as partition onto the apparatus, volatilization, and partition onto the biomass. The parameters required to describe these processes were obtained by independent experiments. The yield coefficient could be determined within a small range. However, the specific growth rate and the half-saturation constant were found to vary widely, with pairs of them describing the system adequately. It was shown that partition and volatilization processes can significantly affect the determination of the yield and Monod kinetic coefficients and need to be taken into account. (c) 1996 John Wiley & Sons, Inc.     

Dominant-negative mutants of platelet-derived growth factor revert the transformed phenotype of human astrocytoma cells.

Malignant astrocytoma is the most common primary human brain tumor. Most astrocytomas express a combination of platelet-derived growth factor (PDGF) and PDGF receptor which could close an autocrine loop. It is not known whether these autocrine loops contribute to the transformed phenotype of astrocytoma cells or are incidental to that phenotype. Here we show that dominant-negative mutants of the PDGF ligand break the autocrine loop and revert the phenotype of BALB/c 3T3 cells transformed by the PDGF-A or PDGF-B (c-sis) gene. Then, we show that these mutants are selective in that they do not alter the phenotype of 3T3 cells transformed by an activated Ha-ras or v-src gene or by simian virus 40. Finally, we show that these mutants revert the transformed phenotype of two independent human astrocytoma cell lines. They have no effect on the growth of human medulloblastoma, bladder carcinoma, or colon carcinoma cell lines. These observations are consistent with the view that PDGF autocrine loops contribute to the transformed phenotype of at least some human astrocytomas.     

Brain glucose bisphosphatase requires inosine monophosphate

Glucose bisphosphate phosphatase has been partially purified from the cytosol of mouse brain. Enzyme activity required Mg2+ and a heat-stable cofactor. The activator was present in boiled extracts of mouse brain mitochondrial-nuclear fraction, of red blood cells, or of rabbit muscle. The chemical properties of the activator are consistent with its identification as inosine monophosphate (IMP), including its mobility in a high pressure liquid chromatography (HPLC) system capable of resolving all of the biologically important mononucleotides. A large number of other biologically important compounds were not effective, including AMP, cAMP, cGMP, and UMP, GMP, purified by HPLC, (50 or 74 microM), gave a rate about 35% of that obtained with IMP (5 microM). The enzyme was separated completely from phosphoglucomutase and significantly from glucose bisphosphate synthase. The products of the reaction are glucose-P and Pi. Fructose bisphosphate at 500 microM inhibited only 40% in the presence of 20 microM glucose bisphosphate. The activation by IMP follows hyperbolic kinetics with an apparent Ka of 5 microM in the presence of 12 microM glucose bisphosphate. The apparent Km of glucose bisphosphate was 10 microM in the presence of 50 microM IMP. There was no inhibition by 5 or 50 microM AMP or ADP. The possible regulatory importance of glucose bisphosphate in carbohydrate metabolism and the significance of the regulation of the phosphatase by the nucleotide are discussed.     

Blood parameters of two hill stream cobitids in relation to their habitat

The blood of two fresh water cobitids — Botia lohachata, an exclusive water breathing form and Lepidocephalus guntea a dual breather, — showed a comparatively higher range of Hb (16.0–19.0 g%), Hct (50.0–61.1%) and number of RBC (2.71–6.7 millions/mm³) than many other water and air breathing fishes. Significant sexual difference exists in these characteristics (P > 0.05).The impact of life in oxygen depleted water, also inhabited by L. guntea as a result of its air breathing habit, is well reflected in its greater RBC size (11.86 × 8.66 µm) and their larger surface area (83.96 µm²) compared to that of Botia (53.16 µm²). The smaller size (9.92 × 6.45 µm) and consequently greater number of erythrocytes (4.67 millions/mm³) in Botia, are related to its active mode of life in the swiftly flowing water of hilly rivers. Though the higher nucleo-cytoplasmic ratio of 1 : 5.2 in Botia and 1 : 6.9 in Lepidocephalus suggest a slower red cell metabolism, the greater number of erythrocytes seems to have compensated for their active mode of life.     

Genetic variants associated with breast cancer risk for Ashkenazi Jewish women with strong family histories but no identifiable BRCA1/2 mutation

The ability to establish genetic risk models is critical for early identification and optimal treatment of breast cancer. For such a model to gain clinical utility, more variants must be identified beyond those discovered in previous genome-wide association studies (GWAS). This is especially true for women at high risk because of family history, but without BRCA1/2 mutations. This study incorporates three datasets in a GWAS analysis of women with Ashkenazi Jewish (AJ) homogeneous ancestry. Two independent discovery cohorts comprised 239 and 238 AJ women with invasive breast cancer or preinvasive ductal carcinoma in situ and strong family histories of breast cancer, but lacking the three BRCA1/2 founder mutations, along with 294 and 230 AJ controls, respectively. An independent, third cohort of 203 AJ cases with familial breast cancer history and 263 healthy controls of AJ women was used for validation. A total of 19 SNPs were identified as associated with familial breast cancer risk in AJ women. Among these SNPs, 13 were identified from a panel of 109 discovery SNPs, including an FGFR2 haplotype. In addition, six previously identified breast cancer GWAS SNPs were confirmed in this population. Seven of the 19 markers were significant in a multivariate predictive model of familial breast cancer in AJ women, three novel SNPs [rs17663555(5q13.2), rs566164(6q21), and rs11075884(16q22.2)], the FGFR2 haplotype, and three previously published SNPs [rs13387042(2q35), rs2046210(ESR1), and rs3112612(TOX3)], yielding moderate predictive power with an area under the curve (AUC) of the ROC (receiver-operator characteristic curve) of 0.74. Population-specific genetic variants in addition to variants shared with populations of European ancestry may improve breast cancer risk prediction among AJ women from high-risk families without founder BRCA1/2 mutations.     

Influence of Physicochemical Parameters on the Abundance of Coliform Bacteria in an Industrial Site of the Hooghly River, India

Industrial effluents from jute, paper, pulp mills and sewage from households are regularly discharged into the Hooghly River. It generates a potential risk for both humans and animals of the area concerned. In the present study, water quality of the Hooghly River passing by the site of a growing township (Naihati, North 24 Parganas, West Bengal, India) was assessed throughout the year 2010 on the basis of the data collected on the physicochemical and microbiological parameters. The water samples collected on each month revealed the presence of higher amount of coliform bacteria, Streptococcus sp. and Escherichia coli, than the standard limit. Different physicochemical parameters like chemical oxygen demand, biological oxygen demand, dissolved oxygen (DO), total suspended solids, total dissolved solids (TDS), total hardness, alkalinity, chlorinity, nitrate and nitrite of the water at the sampling sites were found to be considerably higher than the levels standardized by WHO (2006). It was found that the relative abundance of Streptococcus and E. coli was influenced by two independent variables (water quality parameters), namely, DO and TDS. The abundance of coliform bacteria in the water sample warrants the adoption of proper measures to reduce the pollution level at the point source on way of scientific disposal of industrial effluents.     

Establishment of a Captive All‐male Group of Proboscis Monkey (Nasalis larvatus) at the Singapore Zoo

Surplus male proboscis monkeys at the Singapore Zoo pose a considerable problem for maintenance and maximizing of exhibition potential. In 2008, a new exhibit was constructed to house and display a group of six proboscis monkey males born in Singapore Zoo. To document and monitor the all‐male group establishment in the new exhibit, we conducted observations on intragroup interactions between the monkeys, spatial use of their new exhibit, and visitor effects on their behavior. We found contact aggressive interactions between the monkeys to be consistently lower than noncontact aggressive interactions and by week six of introduction to the new exhibit, contact aggression was almost nonevident. Affiliative interactions also developed between individuals in the group, with an interface of aggressive and socioreconcilatory behavior influenced by food competition and a dominance hierarchy. This was evident from significantly higher overall aggression and affiliation during feeding times compared to nonfeeding times, and this was reduced when food competition was mitigated by modifying the feeding regime. We measured the groups’ spatial use of the exhibit and the relation to behavior, crowd size, and density. Our results showed that the proboscis monkeys utilized the available exhibit space, were largely unaffected by visitor crowd size and density, and were able to exhibit a variety of natural behaviors, including swimming. Our accomplishment in maintaining and displaying an all‐male group of proboscis monkeys in captivity provides viable options for more comprehensive captive management and breeding programs for this endangered species. Zoo Biol. 32:281‐290, 2013. © 2012 Wiley Periodicals, Inc.     

Effects of Culling on Mesopredator Population Dynamics

Anthropogenic changes in land use and the extirpation of apex predators have facilitated explosive growth of mesopredator populations. Consequently, many species have been subjected to extensive control throughout portions of their range due to their integral role as generalist predators and reservoirs of zoonotic disease. Yet, few studies have monitored the effects of landscape composition or configuration on the demographic or behavioral response of mesopredators to population manipulation. During 2007 we removed 382 raccoons (Procyon lotor) from 30 forest patches throughout a fragmented agricultural ecosystem to test hypotheses regarding the effects of habitat isolation on population recovery and role of range expansion and dispersal in patch colonization of mesopredators in heterogeneous landscapes. Patches were allowed to recolonize naturally and demographic restructuring of patches was monitored from 2008–2010 using mark-recapture. An additional 25 control patches were monitored as a baseline measure of demography. After 3 years only 40% of experimental patches had returned to pre-removal densities. This stagnant recovery was driven by low colonization rates of females, resulting in little to no within-patch recruitment. Colonizing raccoons were predominantly young males, suggesting that dispersal, rather than range expansion, was the primary mechanism driving population recovery. Contrary to our prediction, neither landscape connectivity nor measured local habitat attributes influenced colonization rates, likely due to the high dispersal capability of raccoons and limited role of range expansion in patch colonization. Although culling is commonly used to control local populations of many mesopredators, we demonstrate that such practices create severe disruptions in population demography that may be counterproductive to disease management in fragmented landscapes due to an influx of dispersing males into depopulated areas. However, given the slow repopulation rates observed in our study, localized depopulation may be effective at reducing negative ecological impacts of mesopredators in fragmented landscapes at limited spatial and temporal scales.