Percorrer por autor "Carvalho, Marta"
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- Hygiene Indicators and Salmonellae on Surfaces of Swine Carcasses from Two Slaughterhouses in Northern PortugalPublication . Moura-Alves, Márcio; Carvalho, Marta; Baggio Ribeiro, Deise Helena; Barbosa, Joana; Silveira, Leonor; Pista, Ângela; Pinto, Helena Patrícia; Saraiva, Cristina; Teixeira, Paula; Esteves, AlexandraAbstract: The monitoring of carcass surface contamination along the slaughter line enables verification of slaughter operation hygiene and the use of good manufacturing practices. Pork meat is a common source of human nontyphoidal salmonellosis, one of the most frequently reported foodborne illnesses worldwide. This study was conducted to gather data on microbial loads before and after evisceration on the surfaces of swine carcasses in two slaughterhouses. The presence of Salmonella enterica was evaluated only after evisceration on carcass surfaces and in livers and floor drains (environmental samples) because pigs are common carriers of this pathogen. The contamination of carcass surfaces was evaluated by delimitation of surface area with sterilized templates (100 cm2), and surface samples were collected with gauze swabs. Total aerobic mesophilic bacteria, Enterobacteriaceae, and Escherichia coli were enumerated. Significant differences (P < 0.05) in counts of mesophilic bacteria, Enterobacteriaceae, and E. coli were found on the external carcass surfaces, with higher counts after evisceration. The neck and abdominal areas had higher levels of mesophilic bacteria, Enterobacteriaceae, and E. coli and a high prevalence of Salmonella. Salmonella was detected in only one of the studied slaughterhouses; 19 (7.3%) of 259 analyzed carcass samples were positive for Salmonella, and Salmonella was detected in two livers and two floor drains. A total of 52 Salmonella isolates (44 from carcasses, 5 from livers, and 3 from drains) were recovered. Three Salmonella serovars (Typhimurium 4,5:i- , Wernigerone, and Derby) were identified, and 53.8% of the 52 isolates were multidrug resistant. The results reveal the need for continuous improvement of slaughtering operations and implementation of good manufacturing practices to ensure the safety of pork produced in Portugal.
- Incorrect DNA methylation of the DAZL promoter CpG island associates with defective human spermPublication . Navarro-Costa, Paulo; Nogueira, Paulo; Carvalho, Marta; Leal, Fernanda; Cordeiro, Inês; Calhaz-Jorge, Carlos; Gonçalves, João; Plancha, Carlos E.Background: Successful gametogenesis requires the establishment of an appropriate epigenetic state in developing germ cells. Nevertheless, an association between abnormal spermatogenesis and epigenetic disturbances in germline-specific genes remains to be demonstrated. Methods: In this study, the DNA methylation pattern of the promoter CpG island (CGI) of two germline regulator genes—DAZL and DAZ, was characterized by bisulphite genomic sequencing in quality-fractioned ejaculated sperm populations from normozoospermic (NZ) and oligoasthenoteratozoospermic (OAT) men. Results: OAT patients display increased methylation defects in the DAZL promoter CGI when compared with NZ controls. Such differences are recorded when analyzing sperm fractions enriched either in normal or defective germ cells (P , 0.001 in both cases). Significant differences in DNA methylation profiles are also observable when comparing the qualitatively distinct germ cell fractions inside the NZ and OAT groups (P ¼ 0.003 and P ¼ 0.007, respectively). Contrastingly, the unmethylation pattern of the DAZ promoter CGI remains correctly established in all experimental groups. Conclusions: An association between disrupted DNA methylation of a key spermatogenesis gene and abnormal human sperm is described here for the first time. These results suggest that incorrect epigenetic marks in germline genes may be correlated with male gametogenic defects.