Timed artificial insemination in beef cattle using GnRH agonist, PGF2alpha and estradiol benzoate (EB)

The present work evaluated low-cost protocols for timed artificial insemination (TAI) in beef cattle. In Experiment 1, cycling nonlactating Nelore cows (Bos indicus, n=98) were assigned to the following groups: GnRH-PGF (GP) and GnRH-PGF-GnRH (GPG), whereas cycling (n=328, Experiment 2) or anestrus (n = 225, Experiment 3) lactating (L) cows were divided into 3 groups: GP-L, GPG-L and GnRH-PCF-Estradiol benzoate (GPE-L). In Experiment 4, lactating cows (n=201) were separated into 3 groups: GP-L, GPE-L and G 1/2PE-L. Animals from Experiment 1, 3 and 4 were treated (Day 0), at random stages of the estrous cycle, with 8 mug of buserelin acetate (GnRH agonist) intramuscularly (im), whereas in Experiment 2 half of the cows received 8 and the other half 12 mug of GnRH (im). Seven days later (D 7) all animals were treated with 25 mg of dinoprost trometamine (PGF2 alpha, im) except those cows from the G 1/2PE-L group which received only 1/2 dose of PGF2 alpha (12.5 mg) via intravulvo-submucosa (ivsm). Alter PGF2 alpha injection the animals from the control groups (GP and GP-L) were observed twice daily to detect estrus and Al was performed 12 h afterwards. The cows from the other groups received a second GnRH injection (D 8 in GPG-L and d9 in GPG groups) or one injection of estradiol benzoate (EB, 1.0 mg, D 8 in GPE-L group). All cows from GPG and GPG-L or GPE-L groups were AI 20 to 24 or 30 to 34 h, respectively, after the last hormonal injection. Pregnancy was determined by ultrasonography or rectal palpation 30 to 50 days after AI. In the control groups (GP and GP-L) percentage of animals detected in heat (44.5 to 70.3%) and pregnancy rate (20 to 42%) varied according to the number of animals with corpus luteum (CL) at the beginning of treatment. The administration of a second dose of GnRH either 24 (Experiment 2) or 48 h (Experiment 1) after PGF2 alpha resulted in 47.7 and 44.9% pregnancy rates, respectively, after TAI in cycling animals. However, in anestrus cows the GPG treatment induced a much lower pregnancy rate (14.9%) after TAI. The replacement of the second dose of GnRH by EB (GPE-L) resulted in a pregnancy rate (43.3%) comparable to that obtained after GnRH treatment (GPG-L, 47.7%, Experiment 2). Furthermore, the use of 1/2 dose of PGF2 alpha (12.5 mg ivms, Experiment 4) resulted in pregnancy rate (43.5%) similar to that observed with the full dose (im). Both protocols GPG and GPE were effective in synchronizing ovulation in cycling Nelore cows and allowed approximately a 45% pregnancy rate after TAI. Additionally, the GPE treatment is a promising alternative to the use of GPG in timed Al of beef cattle, due to the low cost of EB when compared to GnRH agonists. (C) 2001 by Elsevier B.V.

Snake venom phospholipase A(2) inhibitors: Medicinal chemistry and therapeutic potential

Phospholipases A(2) (PLA(2)s) are commonly found in snake venoms from Viperidae, Hydrophidae and Elaphidae families and have been extensively studied due to their pharmacological and physiopathological effects in living organisms. This article reports a review on natural and artificial inhibitors of enzymatic, toxic and pharmacological effects induced by snake venom PLA(2)s. These inhibitors act on PLA(2)S through different mechanisms, most of them still not completely understood, including binding to specific domains, denaturation, modification of specific amino acid residues and others. Several substances have been evaluated regarding their effects against snake venoms and isolated toxins, including plant extracts and compounds from marine animals, mammals and snakes serum plasma, in addition to poly or monoclonal antibodies and several synthetic molecules. Research involving these inhibitors may be useful to understand the mechanism of action of PLA(2)s and their role in envenomations caused by snake bite. Furthermore, the biotechnological potential of PLA(2) inhibitors may provide therapeutic molecular models with antiophidian activity to supplement the conventional serum therapy against these multifunctional enzymes.

Messenger ribonucleic acid abundance of intestinal enzymes and transporters in feed-restricted and refed chickens at different ages

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Taxa de desenvolvimento de Chrysomya albiceps(Wiedemann) (Diptera: Calliphoridae) em dieta artificial acrescida de tecido animal para uso forense

Forensic entomology uses biological and ecological aspects of necrophagous insects to help in criminal investigations to estimate the post-mortem interval (PMI) or to determine the cause of death. Recent papers demonstrated that the presence of toxins in decomposing tissues may alter the insect developmental rate of insects exploiting such tissues as food. Thus, preliminary tests with artificial diets in laboratory are necessary to create a database to investigate and quantify the modifications that can occur with the collected insects from a criminal scene, avoiding any errors on the PMI estimates. The present study aimed to evaluate the developmental rate of Chrysomya albiceps (Wiedemann) reared on: a) artificial diets containing animal tissues: bovine liver (D1), raw muscle (D2), stomach (D3), and chicken heart (D4); b) artificial diet without animal tissue (D5); and c) a control group (C), which had only meat. The efficiency of each substrate was assessed by immature weight gain (mg), larval developmental time, larval and pupal survival, emergence interval and adult size. D1 to D4 diets did not restrict C. albiceps development; however, larvae reared on D1 and D2 diets presented a lower adult emergence rate. D3 and control group showed similarities regarding the efficiency parameters (rate and emergence interval). Thus, the use of diet D3, artificial diet with stomach, is the most recommended.

Influence of light intensity and salt-treatment on mode of photosynthesis and enzymes of the antioxidative response system of Mesembryanthemum crystallinum

The metabolic switch From C-3-photosynthesis to crassulacean acid metabolism (CAM),and the antioxidative response of Mesembryanthemum crystallinum L. plants cultured under severe salt stress and high light intensities, and a combination of booth stress conditions, were studied. High light conditions led to a more rapid CAM induction than salinity. The induction time was still shortened when both stress factors were combined. A main pattern observed in CAM plants was a decrease in mitochondrial Mn-superoxide dismutase (SOD) activity during the day. The activities of the chloroplastic Fe-SOD and cytosolic CuZn-SOD were increased due to salt treatment after a lag phase, while catalase activity was decreased. Combination of salt and light stress did not lead to a higher SOD activity as found after application of one stress factor alone, indicating that there is a threshold level of the oxidative stress response. The fact that salt-stressed plants grown under high light conditions showed permanent photoinhibition and lost the ability for nocturnal malate storage after 9 d of treatment indicate serious malfunction of metabolism, leading to accelerated senescence. Comparison of CuZn-SOD activity with CuZn-SOD protein amount, which was determined immunologically, indicates that the activity of the enzyme is at least partially post-translationally regulated.

Enzymes in juice processing: a review

P>The use of enzymes in juice industry has contributed in increasing the yield and production of various types of juices. The addition pectinases aims in particular to degrade the pectic substances, in the cell wall and middle lamella of the cells of plants, aiming to minimise the impacts of these compounds on the characteristics of the final product, such as colour, turbidity and viscosity. Enzymes able to remove bitterness of citrus juice, extract pigments, among other applications, have also had great interest in the juice industry.

Seasonal variation of biomass and productivity of the periphytic community on artificial substrata in the Jurumirim Reservoir (São Paulo, Brazil)

The seasonal variation of the periphytic community attached to an artificial substratum (glass tubes) was studied during two different periods in a lagoon connected to the Paranapanema River, the main tributary of the Jurumirim Reservoir (São Paulo-Brazil). An analysis of dry weight, ash free dry weight, chlorophyll a, phaeophytin and primary productivity of periphyton was carried out. The first experiment lasted from August to December 1993, the second from February to June 1994. Tubes were removed after 7, 14, 21, 28, 60, 90 and 119 days of incubation. In the 1st experiment, the periphytic community reached a higher biomass after the 4th week of colonization (28th day), in the 2nd experiment after the 2nd week (14th day). This discrepancy is related to seasonal differences in environmental factors (water temperature, nutrients concentrations and water discharge) that determine initial colonization. After the first stages of colonization, the biomass and primary productivity of periphyton reached their maximum values after the 60th day of incubation. In both experiments, three developmental phases could be discerned. In the initial phase, an exponential growth was observed. In the second phase, the bioderm reached its maximum biomass and productivity. In the third phase, a decrease of biomass and productivity occurred.

Colonização por macroinvertebrados bentônicos em substrato artificial e natural em um riacho da serra de Itatinga, São Paulo, Brasil

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

Morphological modifications induced by an artificial diet on the hypopharyngeal glands of Apis mellifera (Hymenoptera, apidae) during their degenerative process

The morphological aspects of the hypopharyngeal glands were analyzed in worker bees of Apis mellifera of 15 and 30 days of age. The individuals were kept in a room with controlled temperature at 32degreesC where they received water and either a protein or a high energy food. Nurse and foraging workers were used as a control for the experiment. The morphological results showed that the different diets modified the cell death characteristics and intensified its occurrence. Both diets caused precocious glandular degeneration. However, this anticipation of cell death was more pronounced in the glandular tissue of the workers who received the high energy diet when compared to the glands of the bees fed with the protein meal.The degenerative signs observed were an intense cytoplasmic vacuolization, with a loss of cytoplasm and of the cell boundaries, dilation or condensation of the cells and nuclei, and nuclear fragmentation. At the end of the degenerative process, we observed the extrusion of nuclei and, finally, the dissolution of the glands. The hypopharyngeal glands' remains were found in the haemolymph.

Molecular models for shikimate pathway enzymes of Xylella fastidiosa

The Xylella fastidiosa is a bacterium that is the cause of citrus variegated chlorosis (CVC). The shikimate pathway is of pivotal importance for production of a plethora of aromatic compounds in plants, bacteria, and fungi. Putative structural differences in the enzymes from the shikimate pathway, between the proteins of bacterial origin and those of plants, could be used for the development of a drug for the control of CVC. However, inhibitors for shikimate pathway enzymes should have high specificity for X. fastidiosa enzymes, since they are also present in plants. In order to pave the way for structural and functional efforts towards antimicrobial agent development, here we describe the molecular modeling of seven enzymes of the shikimate pathway of X. fastidiosa. The structural models of shikimate pathway enzymes, complexed with inhibitors, strongly indicate that the previously identified inhibitors may also inhibit the X. fastidiosa enzymes. (C) 2004 Elsevier B.V. All rights reserved.

Action of the chemical agent fipronil (active ingredient of acaricide Frontline (R)) on the liver of mice: An ultrastructural analysis

Fipronil, active ingredient of the acaricide Frontiline (R), is a phenyl-pyrazolic derivative, and its efficacy in the elimination of several plagues, even in low concentrations, has already been demonstrated; however, its effect on nontarget organisms has not been thoroughly explained. In this sense, the objective of this study was to evaluate the effects of different dosages of fipronil on the liver of mice in artificial conditions. Results showed that the animals exposed to fipronil present significant ultrastrucutural changes in hepatic cells with evident cellular and cytoplasm disorganization in hepatocytes characterized by an increase in the number of organelles, mainly mitochondria and rough endoplasmic reticulum, organelles that, in the case of the exposed animals, were probably responsible for the enzymes' synthesis that have the function of inactivating the toxic metabolites. A fat accumulation in the hepatocytes' cytoplasm (steatosis) was observed, in addition to extended vacuolated areas, mainly in regions next to the cell nucleus. Alterations observed in the nuclei of the hepatocytes pointed out cell death processes. Moreover, Kupffer cells increased in number (hyperplasia) suggesting an increase in the phagocytic activity of the liver in the exposed animals. Microsc. Res. Tech., 2011. (c) 2011 Wiley Periodicals, Inc.

Effects of Spider Venom Toxin PWTX-I (6-Hydroxytrypargine) on the Central Nervous System of Rats

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