Purification and properties of buffalo (Bubalus bubalis) erythrocyte hexokinase

Buffalo erythrocytes contain one isozyme of hexokinase that apparently lacks microheterogeneity as shown by chromatographic properties. A single protein band was detected by means of Western blotting using an antibody raised in rabbits against homogeneous rat brain hexokinase I. The native protein has a molecular weight of 200,000 +/- 2880 by gel filtration. Partial purification of erythrocyte hexokinase by a combination of several procedures, including affinity chromatography, which was previously applied successfully to the purifica tion of other mammalian type I hexokinases, produced a partially purified enzyme that showed several contami nants after SDS-polyacrylamide gel electrophoresis. The affinity of buffalo erythrocyte hexokinase for glucose (K-m = 0.012 +/- 0.001 mM) is lower than most other mammal hexokinases type I. It phosphorylates other sugars, with considerably higher K-m values. This isozyme is able to use MgATP but does not use MgGTP, MgCTP or MgUTP. We used inhibition patterns, obtained with products to elucidate enzyme sequential mechanisms. Our results are clearly in agreement with a random sequential mechanism and in disagreement with an ordered sequential mechanism with either glucose or ATP as the obligatory first substrates. The ADP inhibition was of mixed type with both ATP and glucose as substrates. (C) 1997 Elsevier B.V.

EVALUATION of COVERING MATERIALS IN INDIVIDUAL SHELTERS and ITS EFFECTS on PHYSIOLOGICAL RESPONSES and PERFORMANCE of DAIRY CALVES

In Tropical regions, the animal performance is often affected by climate conditions. This study aimed to evaluate covering materials in individual shelters, normally used to house dairy calves, and its influence on the calves physiology and performance. The design used was completely randomized, with a 2x3 factorial arrangement to compare the averages of 5% through the Tukey's test, i.e., both genders-and three types of covering in the shelters (Z - zinc; AC - asbestos cement; and WPAC - white-painted asbestos cement). Parameters evaluated included daily weight gain (DWG), dry matter intake (DMI), feed conversion (FC), rectal temperature (RT), and respiratory frequency (RF). Results showed significant differences (P < 0.05) among males (1.04kg/day) and females (0.74kg/day) for DWG and interaction between gender and treatment (P < 0.05) for zinc covering (0.562kg/day for females and 1.120kg/day for males). Significant differences were also observed in FI of animals housed under shelters with the covering of zinc (48.35kgDM/day for females and 96.91 kgDM/day for males). There were no significant differences (P > 0.05) in the FC and the RT, and there were significant differences (P < 0.05) for RF in the Z treatments (56.9 mov.min(-1)), WPAC (62.2 mov.min(-1)) and FC (70.25 mov.min-1). It was concluded that different covering materials did not affect performance and dry matter intake of dairy calves. However, the animals' physiology of thermoregulation was altered by the different covering materials used in individual shelters.

Transplacental Transfer of Iron in the Water Buffalo (Bubalus bubalis): Uteroferrin and Erythrophagocytosis

The objectives of this investigation were to understand transplacental transport of iron by secreted uteroferrin (UF) and haemophagous areas of water buffalo placenta and clarify the role(s) of blood extravasation at the placental-maternal interface. Placentomes and interplacentomal region of 51 placentae at various stages of gestation were fixed, processed for light and transmission electron microscopy, histochemistry and immunohistochemistry. Haemophagous areas were present in placentomes collected between 4 and 10 months of pregnancy. Perl's reaction for ferric iron was negative in placentomes, but positive in endometrial glands. Positive staining for UF indicated areas in which it was being taken up by phagocytosis and/or fluid phase pinocytosis in areolae of the interplacentomal mesenchyme, with little staining in endometrial stroma. Imunohistochemistry detected UF in trophectoderm of haemophagous regions of placentomes and in other parts of the foetal villous tree, but the strongest immunostaining was in the epithelial cells and lumen of uterine glands. Ultrastructural analyses indicated that erythrophagocytosis was occurring and that erythrocytes were present inside cells of the chorion that also contained endocytic vesicles and caveolae. Results of this study indicate that both the haemophagous areas of placentomes and the areolae at the interface between chorion and endometrial glands are important sites for iron transfer from mother to foetal-placental tissues in buffalo throughout pregnancy.

The relationship between dairy cow hygiene and somatic cell count in milk

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Molecular characterization of Cryptosporidium spp. in dairy calves from the state of So Paulo, Brazil

Cryptosporidiosis is a common protozoan disease observed in a wide range of vertebrate hosts, including ruminants. Cattle can be a potential reservoir of Cryptosporidium spp., leading to environmental contamination with oocysts of zoonotic species. The molecular characterization of Cryptosporidium spp. isolated from cattle from the state of So Paulo, Brazil, was accomplished using nested polymerase chain reaction for amplification of fragments of the 18S rRNA gene and the glycoprotein GP60 gene, following sequencing of amplified fragments. Positivity for Cryptosporidium was found in 10.7% (21/196) of the samples. Four species of Cryptosporidium were identified: C. andersoni, C. bovis, C. parvum subtype IIaA15G2R1, and C. ryanae. To the best of our knowledge, this is the first report of infection by C. ryanae and C. parvum IIaA15G2R1 in cattle from Brazil.