Rumen bacterial and fungal degradation of Digitaria pentzii grown with or without sulfur.

Sheep fed the forage Digitaria pentzii fertilized with sulfur were compared with those fed unfertilized forage for the rumen microbial population involved with fiber degradation. No differences were detected in the bacterial population as determined by anaerobic cultures on a habitat-simulating medium, xylan, or pectin, by 35S labeling techniques for microbial protein, or by transmission electron microscopic studies of bacterium-fiber interactions. Rumen volume and water flow from the rumen were not different for sheep fed each of the forages. Rumen fungi were prevalent in sheep fed sulfur-fertilized D. pentzii as shown by sporangia adhering to forage fiber and by colonies developing from zoospores in roll tubes with cellobiose plus streptomycin and penicillin. Fungi were absent or in extremely small numbers in sheep fed unfertilized forage. Nylon bag digestibility studies showed that the fungi preferentially colonized the lignified cells of blade sclerenchyma by 6 h and caused extensive degradation by 24 h. In the absence of bacteria in in vitro studies, extensive hyphal development occurred; other lignified tissues in blades (i.e., mestome sheath and xylem) were attacked, resulting in a residue with partially degraded and weakened cell walls. Nonlignified tissues were also degraded. Breaking force tests of leaf blades incubated in vitro with penicillin and streptomycin and rumen fluid from sheep fed sulfur-fertilized forage or within nylon bags in such sheep showed a residue at least twice as fragile as that from sheep fed unfertilized forage. In vitro tests for dry matter loss showed that rumen fungi, in the absence of actively growing bacteria, could remove about 62% of the forage material. The response of rumen fungi in sheep fed sulfur-fertilized D. pentzii afforded a useful in vivo test to study the role of these microbes in fiber degradation. Our data establish that rumen fungi can be significant degraders of fiber and further establish a unique role for them in attacking and weakening lignocellulosic tissues. The more fragile residues resulting from attack by fungi could explain the greater intake consistently observed by sheep eating sulfur-fertilized compared with unfertilized D. pentzii forage.     

Rumen Protozoal Degradation of Structurally Intact Forage Tissues

The association with and digestion of intact leaf sections of cool- and warm-season grasses by cattle rumen protozoa were investigated by light and scanning electron microscopy and by in vitro dry matter disappearance studies. Within extensively degraded areas of mesophyll tissue in cool-season forages, almost all protozoa were Epidinium ecaudatum form caudatum, with maximum numbers at 4 to 10 h of incubation. However, few protozoa were found inside warm-season forage leaves. In in vitro dry matter disappearance studies of a series of incubations with and without 1.6 mg of streptomycin per ml, which inhibited the cellulolytic activity of the bacteria, and in comparison with uninoculated controls, rumen protozoa degraded 11.0 and 3.7 percentage units of orchardgrass and bermuda-grass, respectively. Scanning electron microscopy showed that the tissues degraded in orchardgrass consisted of large amounts of mesophyll and portions of the parenchyma bundle sheath and epidermis; no tissue loss due to the protozoa was observed in bermudagrass. The relationship of these observations to forage digestion is discussed.     

Cycling in simple genetic systems

We describe the — unexpected — occurrence of stable limit cycles in the two locus, two allele model. No frequency dependence is involved. The cycles are due to the interaction between recombination and natural selection.This work received support from the National Science Foundation and the Research Foundation of the City University of New York     

Ghrelin immunohistochemistry of gastric adenocarcinoma and mucoepidermoid carcinoma of salivary gland.

Ghrelin (G-HH) synthesized in several tissues including salivary and stomach glands stimulates appetite in humans by modulating neuropeptide Y neurons in the hypothalamic arcuate nucleus. Loss of appetite is one of the most important symptoms of stomach cancer. We conducted a study using immunohistochemistry to determine whether salivary glands and stomach cancer tissues produce ghrelin. We determined that negative ghrelin immunohistochemistry discriminates tumors from normal tissues and may therefore further our understanding of the clinically important problem of reduced food intake and anorexia in cancer patients. Radioimmunoassay analyses confirmed that cancer cells do not produce a G-HH peptide, whereas normal cells yield this peptide.     

Effects of diethylstilbestrol in human lymphocytes in vitro: A dose and time-dependent study on genotoxic, cytotoxic and apoptotic effects

Most of the biological, chemical or physical agents that cause cell death in certain doses and time of exposure may induce either apoptosis or necrosis. This study explores in what ways the genotoxic, cytotoxic and apoptotic effects of diethylstilbestrol (DES), a chemical agent currently used in the treatment of various types of cancer, on the human lymphocytes depend upon the dose and the exposure time. For this purpose, firstly it aims to determine in what dosages and durations of DES treatment, genotoxicity and cytotoxicity in human lymphocytes occur in vitro. Secondly, it explores the effects of DES on sister-chromatid exchanges (SCEs) and apoptosis and their relation with the nitric oxide (NO) levels. Finally, it investigates whether different dosages of DES and duration of treatment with it are correlated with each other. In so doing, we investigated the relationship among the viability, necrosis and apoptosis rates of human lymphocytes which were treated with five different DES concentrations (1, 5, 10, 15 and 20 μM) for 24, 48 and 72 h, DNA fragmentation analysis of these cells, their mean SCE values and NO levels. We concluded that 5 μM DES at 24 h is the most effective dosage that induces typical features of apoptosis in human lymphocytes. Despite the fact that there are many other studies on the effects of DES on the cancer cells, we thought it might be worth looking into the effects of DES on human lymphocytes in vitro. We meant the present study to contribute to the research done in the field of cancer treatment. (Mol Cell Biochem 276: 45–53, 2005)     

Clinical impact of atypical squamous cells of undetermined significance. A cytohistologic comparison

OBJECTIVE: To assess the percentage of squamous intraepithelial lesions (SILs) in the atypical squamous cells of undetermined significance (ASCUS) cytologic diagnosis. STUDY DESIGN: From January 1994 to December 1995, 421 cervical Pap smears with a diagnosis of ASCUS were followed with cervical biopsies within three months. The ASCUS cytologic diagnosis was correlated with the histologic findings and stratified according to age group, previous abnormal history and cell type of ASCUS (squamoid vs. metaplastic). RESULTS: Histologic diagnosis showed that of ASCUS diagnoses, 13% were normal, 34% were reactive, 4.8% were atypical, 43% were low grade SIL, 4% were high grade SIL, 1% were carcinoma in situ, and none were invasive lesions. The patients in the youngest group, up to 25 years, demonstrated the highest percentage of SIL. Patients with a previous abnormal gynecologic history showed a higher percentage of SIL than those without an abnormal history. SILs were observed in 51.5% of squamoid ASCUS and 36.5% of metaplastic ASCUS. CONCLUSION: Forty-eight percent of females having an ASCUS diagnosis on Pap smears had SIL and thus a preneoplastic lesion. The highest percentage of SIL was found in females 25 years and younger. Our findings suggest that an ASCUS diagnosis warrants ongoing follow-up.     

Heavy metal tolerance potential of Aspergillus strains isolated from mining sites

Increased heavy metal pollution generated through anthropogenic activities into the environment has necessitated the need for eco-friendly remediation strategies such as mycoremediation. With a view to prospecting for fungi with heavy metal remediation potentials, the tolerance of five Aspergillus species isolated from soils of three active gold and gemstone mining sites in southwestern Nigeria to varied heavy metal concentrations was investigated. Isolated Aspergillus strains were identified based on the internal transcribed spacer 1 and 2 (ITS 1 and ITS 2) regions. Growth of Aspergillus strains were challenged with a range of varied concentrations of heavy metals: cadmium (Cd) (0–100), copper (Cu) (0–1000), lead (Pb) (0–400), arsenic (As) (0–500), and iron (Fe) (0–800) concentrations (ppm) incorporated into Malt Extract Agar (MEA) in triplicates. Mycelial radial growths were recorded at intervals of 3 days during a 13-day incubation period. Aspergillus strains were identified as A. tubingensis, A. fumigatus, A. terreus, A. nidulans, and A. nomius. A. tubingensis tolerated Cd, Cu, Pb, As, and Fe at all test concentrations (100–1000 ppm), showing no significant (p > .05) difference compared with the control. Similarly, A. nomius tolerated all concentrations of Cu, Pb, As, and Fe and only 50 ppm Cd concentrations. A. nidulans, A. terreus, and A. fumigatus, on the other hand, tolerated all concentrations of Cu, Pb, and Fe with no statistical significance (p > .05) difference from the controls. Overall, the Aspergillus species showed tolerance to heavy metal concentrations above permissible limits for contaminated soils globally. These heavy metal tolerance traits exhibited by the Aspergillus isolates may suggest that they are potential candidates for bioremediation of heavy metal–polluted environments.