Browsing by Author "Pereira, M."
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- Association of milk traits with SSCP polymorphisms at the growth hormone gene in the Serrana goatPublication . Marques, P. X.; Pereira, M.; Marques, MR; Santos, Ingrid; Belo, Carmona; Renaville, Robert; Cravador, A.The present study suggests the existence of an association between milk production traits and genetic polymorphisms at the growth hormone (GH) gene in the Portuguese indigenous Serrana goat. TheDNAfrom 229 animals of two ecotypes (Jarmelista and Ribatejano)was analysed by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) technique revealing a high degree of genetic polymorphism at the goat GH (gGH) gene. Two conformation patterns were detected in exons 1 and 2, 6 in exon 3, 10 in exon 4 and 5 in exon 5. The evaluation of an association effect between these SSCP patterns with milk, fat and protein yields and fat and protein percentages suggests a positive effect of pattern A/B of exon 4 for Ribatejano ecotype and of pattern A/B of exon 2 for Jarmelista ecotype with milk yield (P < 0.05) and of pattern A/B of exon 1 and pattern B/B of exon 2 with protein percentage (P < 0.05) for Ribatejano ecotype. The results support the hints suggested by previous studies of the importance of the gGH gene as a candidate gene for marker-assisted selection in goat breeds and suggest that exon 4 is a preferential target for further investigation on mutations that influence milk yield variation.
- Growth hormone AluI polymorphism analysis in eight Portuguese bovine breedsPublication . Reis, Clara; Navas, D.; Pereira, M.; Cravador, A.A total of 195 bulls of eight Portuguese beef cattle breeds (Alentejana, Arouquesa, Barros , Maronesa, Marinhoa, Mertolenga, Mirandesa and Preta) were genotyped for the GH AluI polymorphism by the polymerase chain reaction and restriction length polymorphism (PCRRFLP). The genotype and gene frequencies for each breed were determined and shown to be quite variable among the breeds. The overall gene frequencies for L and V were 0.759 and 0.241, respectively. The relation between the bGH-AluI polymorphism and growth performances was ascertained in 168 of the animals analysed. According to our results there is a significant association between the genotypes LL and LV of the bGH and the average live body weight of the animals of the breeds Alentejana, Marinhoa and Preta.
- Polymorphisms at the five exons of gowth hormone gene in the Algarvia Goat. Possible association with milk traitsPublication . Malveiro, Elisabete; Pereira, M.; Marques, P. X.; Santos, Ingrid; Belo, Carmona; Renaville, Robert; Cravador, A.The present preliminary study attempts to establish associations between milk production traits and genetic polymorphisms at the GH gene in the Algarvia goat. The DNA of 108 goats of the indigenous Portuguese Algarvia breed was evaluated.
- Temporal and spatial variation of phytopigments in the Western part of the Ria Formosa lagoon, Southern PortugalPublication . Pereira, M.; Icely, John; Mudge, S.; Newton, Alice; Rubina, R.The spatial and temporal variation of phytoplankton pigments in the western part of Ria Formosa, Portugal, was investigated between September 2000 and July 2002. Sampling stations included the ocean boundary (Anc˜ao inlet) and two different landward boundary situations: 1) the shallow westernmost “blind end” of the lagoon (Ponte) and 2) near a main sewage outlet (Ramalhete). Nutrient concentrations were higher during the first year of sampling but were lower than those recorded in previous studies. This decrease in the concentration of nutrients was possibly the result of the 1997 relocation of the Anc˜ao inlet, which allowed better water circulation in the lagoon. Throughout this study, concentrations of chlorophyll a determined by high-performance liquid chromatography were consistently low. Inter-annual variability in the pattern of chlorophyll a concentration was observed in the form of a bimodal peak (spring/summer and autumn) between September 2000 and June 2001 and more uniformconcentrations from September 2001 until July 2002. Principal component analysis of the concentrations of all pigments did not indicate any spatial- or tidal-related variations but did show that pigment concentrations varied over time. Partial least squares analysis corroborated this temporal shift of the phytoplankton pigment abundance and composition and showed that these shifts could be linked to certain environmental variables. Fucoxanthin was the dominant accessory pigment and was strongly correlated with chlorophyll a. Other marker pigments present in lower concentrations included chlorophyll b, 19′-hexanoyloxyfucoxanthin, neoxanthin, alloxanthin, diadinoxanthin, lutein, zeaxanthin, and beta-carotene. PLS analysis was used to infer the dominant phytoplanktonic groups in the lagoon. This analysis established that diatoms and other algal groups with a similar pigment profile dominated the phytoplankton community throughout the year. Cryptophytes were the second most abundant group in the lagoon. The remaining groups, including dinoflagellates, cyanophytes, and chlorophytes, contributed much less to the total algal biomass (generally <10%).