Cytobios最新文献

The Malpighian tubules of Aedes aegypti showed significant differences in their diameters between male and female larvae, male and female pupae, male larvae and male adults and male pupae and male adults. In every case, female values were greater than in males. Measurements of mean nuclear areas of the principal and stellate cells from Malpighian tubules, taken in males and females during development, showed that this parameter in both types of cell was significantly greater in females than in male larvae, pupae and adult stages. In males, significant differences between developmental stages were observed only in comparison with the nuclear area of larvae and adults in the principal cells, but in females, every comparison between stages showed significant differences except between pupae and adults in stellate cells. The frequency distribution of nuclear area values, in development, for male stellate and principal cells, were mostly concentrated in the first seven classes among the 30 classes considered in every stage, while for females, the frequency dropped drastically in the same classes from larvae to pupae and adults, moving to classes of higher values. Considering the importance of Malpighian tubules in insect physiology, the meaning of the differences detected are discussed on the basis of different metabolic levels, between sexes and developmental stages.

A mycoparasite identified as Thamnocephalis quadrupedata (Mucorales) was observed on cultures of the frog dung fungus, Basidiobolus ranarum. The parasitic fungus, T. quadrupedata possessed infection hyphae with appressoria and penetrating hyphae to attack their host prey and adhere firmly to the surface. The invasion was often by slender infection hyphae or infecting pegs which grew from the appressoria and penetrated the chitin-protein cuticle by both mechanical pressure and exocellular enzymes. The host fungus, B. ranarum, possessing primary conidia, capilliconidia, hyphal bodies, vegetative mycelia and zygospores, were infected by means of direct penetration and intrahyphal growth, resulting in host cell death. T. quadrupedata may also grow as a saprophyte on damp filter paper in a Petri dish, manifesting facultative necrosis.

The effect of lead exposure on intracellular calcium levels, membrane fluidity, lipid peroxidation, acetylcholinesterase and monoamine oxidase activity and its accumulation in different regions of the brain were studied to understand the molecular mechanism of lead induced neurotoxicity. Lead treatment (20 mg/kg lead nitrate, intraperitoneally, once daily for 15 days) resulted in a significant accumulation of lead in all brain regions with the maximum being in the hippocampus. Levels of glutathione, lipid peroxidation, intracellular calcium and membrane fluidity, as well as the activity of the membrane bound enzymes, acetylcholinesterase and monoamine oxidase, increased to a significant level in certain areas of the rat brain. The results suggest that lead exerts neurotoxic effects by altering certain membrane bound enzymes and may cause oxidative stress.

The expression of Bcl-2, P53 proteins and known markers of proliferation, namely proliferating cell nuclear antigen (PCNA) and Ki67, in 29 patients with B-cell chronic lymphocytic leukaemia (B-CLL) was investigated. All leukaemic patients were classified, and immunophenotyped by the two-colour immunofluorescence method with the use of fluorocytometry. B-CLL was heterogeneous in the range of biological parameters of tumour cells. B-CLL patients manifested 34% positive Ki67 and 61% PCNA expression, whereas Bcl-2 and P53 positivity was 81% and 42%, respectively. The level of intracellular expression of Bcl-2 and P53 proteins did not depend on the stage of disease estimated by routine methods. Ki67 and PCNA expression was significantly higher in B-CLL patients with more advanced stages of the disease. A statistically significant correlation was established between their mutual expression.

The effect of chronic tumour necrosis factor-alpha (TNF-alpha) treatment on the synthesis of specific myofibrillar proteins such as heavy chain myosin, light chain myosin and G-actin in rat diaphragm were evaluated. Muscles (diaphragm) from control and experimental groups (TNF-alpha i.v. at 50 microg/kg body wt for 5 days) were incubated in the presence of 35S-methionine for 2 h. Myofibrillar protein extracts were prepared and protein was electrophoresed on sodium dodecyl sulphate-polyacrylamide gels. Heavy chain myosin, light chain myosin and G-actin were identified by Western blot analysis using specific monoclonal antibodies. Polyacrylamide gel electrophoresis (PAGE) followed by Western blot analysis revealed two types of heavy chain myosin (206 and 212 kD), all four types of light chain myosin (15, 16.5, 18 and 20 kD) and a single type of G-actin (42 kD). Chronic TNF-alpha treatment produced a significant decline in the synthesis of all types of myofibrillar proteins, namely heavy chain myosin, light chain myosin and G-actin. TNF-alpha impaired peptide-chain initiation in diaphragm muscle which was reversed by the branched-chain amino acids (BCAA) therapy of TNF-alpha treated rats. These findings indicate a significant role for TNF-alpha in the translational regulation of protein synthesis in skeletal muscle.

Conventional analysis, C-banding, silver nitrate and base specific fluorochrome staining with chromomycin A3 (CMA3) were used to analyse the meiotic chromosomes of the grasshopper Stiphra robusta. Diploid numbers of 2n = 19 in the males and 2n = 20 in the females were observed. The chromosome complement comprised a graded series of uniarmed chromosomes, and the X chromosome was medium sized. The nucleolar organizer regions, restricted to the bivalent chromosomes 6, 7 and 8, were CMA3 positive.

The constitutive heterochromatin (CH) of Phaeoparia megacephala was studied using C-banding and fluorochrome staining (CMA3, DAPI and acridine orange). The nucleolar organizer regions (NOR) were identified with silver staining. The chromosome complement of this species was 2n = 23, XO in males, and 2n = 24, XX in females. The CH was pericentromeric in all chromosomes. L1, L2, L3 and X chromosomes showed large blocks of CH, while the medium and small chromosomes had small blocks. The staining procedure with acridine orange revealed the same pattern. All the pericentromeric regions showed small blocks of CMA3-positive constitutive heterochromatin (GC-rich regions), while only part of the large C-band positive chromosome segments (L1, L2, L3 and X) were CMA3 positive. This character demonstrates an uncommon heterogeneity of constitutive heterochromatin in P. megacephala. The fluorochrome DAPI did not reveal DAPI-positive regions (AT-rich regions). Silver staining revealed only one pair of medium chromosomes with NOR.

A second function of carbonic anhydrase (CA) isoforms has already been proposed. This involves the dispersal of complexes in which six carbon dioxide molecules sequester a hydroxyl ion when the gas reacts with liquid water. The semi-catalytic reaction does not require the formation of bicarbonate as an essential corollary. This function is, therefore, a likely activity of carbonic anhydrase related proteins that have recently been discovered and which lack the active zinc site essential for the hydration of carbon dioxide. Re-examination of possible functions for the complex of six CO2 molecules with a hydroxyl anion have brought to light several circumstances where the presence of fully reversible complexes could have physiological advantages. A catalytic synthesis and dissolution of the complexes could thus be the important function for the carbonic anhydrase-related proteins (CA-RP) molecules as well as of some CA isoforms. The possible mechanisms for this extended second catalytic function and examples are briefly discussed.

Infection with Methorchis bilis was recognized for the first time in the residents of Novosibirsk area (Russia). During a serological survey (37 patients in toto), it was possible to demonstrate that 48.5% of the serum samples tested possessed antibodies to Opisthorchis felineus antigens, 37.8% to both Opisthorchis felineus and Methorchis bilis antigens, and 13.5% to Methorchis bilis antigens only.

The growth of Dunaliella salina was studied with respect to pH and varying concentrations of NaHCO3 in the medium. The growth rate, photosynthesis and dark respiration were maximal at pH 8 and 4 mM NaHCO3 in the medium. Photosystem I of the Hill reaction was affected more by inorganic carbon concentration than photosystem II.