Carbohydrate carbon sources induce loss of flocculation of an ale-brewing yeast strain

Aims: To identify the nutrients that can trigger the loss of flocculation under growth conditions in an ale-brewing strain, Saccharomyces cerevisiae NCYC 1195. Methods and Results: Flocculation was evaluated using the method of Soares, EX. and Vroman, A. [Journal of Applied Microbiology (2003) 95, 325]. Yeast growth with metabolizable carbon sources (glucose, fructose, galactose, maltose or sucrose) at 2% (w/v), induced the loss of flocculation in yeast that had previously been allowed to flocculate. The yeast remained flocculent when transferred to a medium containing the required nutrients for yeast growth and a sole nonmetabolizable carbon source (lactose). Transfer of flocculent yeast into a growth medium with ethanol (4% v/v), as the sole carbon source did not induce the loss of flocculation. Even the addition of glucose (2% w/v) or glucose and antimycin A (0.1 mg lˉ¹) to this culture did not bring about loss of flocculation. Cycloheximide addition (15 mglˉ¹) to glucose-growing cells stopped flocculation loss. Conclusions: Carbohydrates were the nutrients responsible for stimulating the loss of flocculation in flocculent yeast cells transferred to growing conditions. The glucose-induced loss of flocculation required de novo protein synthesis. Ethanol prevented glucose-induced loss of flocculation. This protective effect of ethanol was independent of the respiratory function of the yeast. Significance and Impact of the Study: This work contributes to the elucidation of the role of nutrients in the control of the flocculation cycle in NewFlo phenotype yeast strains.Instituto Politécnico do Porto (IPP) - Fundo de Apoio à Investigação - Project P24/96 , P24/97.Programa Plurianual de Unidades de I&D-CIEA/ ISEP

Comportamento de células do sistema imune frente ao desafio com Salmonella Enteritidis em aves tratadas e não tratadas com ácidos orgânicos

A Salmonelose é uma importante zoonose, considerada a principal causa de infecções bacterianas, sendo associada ao consumo de produtos avícolas. Como alternativa de controle, ácidos orgânicos têm sido amplamente usados. No entanto, pouco se conhece sobre o estado imunológico de aves de produção, e uma avaliação deste status é necessária para proteger frente a enfermidades e para garantir à aplicação segura de agentes terapêuticos ou imunização profilática. Este trabalho teve como objetivo verificar o comportamento do sistema imunológico das aves previamente infectadas com Salmonella Enteritidis (SE) tratadas com um composto de ácidos orgânicos em diferentes concentrações administrado via água e ração comparando com as aves infectadas e não tratadas. Foram inoculados 120 frangos de corte com 1mL de SE, via oral, na concentração de 1,0 x 108 UFC/mL, no 1º e 2º dia de idade, divididos em seis tratamentos com duas repetições, utilizando 200, 400, 500 e 1000ppm do ácido orgânico. Aos 35 dias de vida das aves, foram coletados, de todos os grupos, alíquotas de sangue de 3mL em tubo contendo EDTA para a avaliação das células imunes através de citometria de fluxo. Foram analisadas as porcentagens circulantes de células CD4+, CD8β+, MHC I+, MHC II+, TCRVβ1+, TCRVβ2+ e CD28+. Para análise microbiológica foram coletadas tonsilas cecais destas aves. Observou-se com esse estudo que os ácidos orgânicos nas dosagens 1000ppm na água e 500ppm na ração durante, dois e sete dias respectivamente antes do abate, foram eficazes na redução da infecção por SE em frangos de corte, comprovadas pelo método microbiológico e demonstradas através do comportamento das células do sistema imune. No presente estudo as aves infectadas apresentaram uma proporção menor de células T auxiliares circulantes quando comparadas às aves infectadas, mas tratadas com o AO ou com o grupo não infectado. A mesma tendência pode ser observada para as células CD28+, TCRVβ1+ e MHC IIbright+, e, com menor resolução, para CD8β+

PCR testing of single tissue samples can result in misleading data on gill-associated virus infection loads in shrimp

In shrimp aquaculture, the ability to reliably test for the presence and load of pathogens is vital for managing disease. As pathogen infection loads are not distributed homogenously throughout different tissues, detection by PCR can vary based on what tissue type is tested. Moreover, there is potential for infection loads to vary within the same tissue type depending on infection severity and nature of the tissue. This study used reverse transcriptase real-time quantitative PCR (RT-qPCR) to examine the sensitivity and variability in gill-associated virus (GAV) detection levels within and between different tissue types sampled from individual black tiger (Penaeus monodon) shrimp. From the group of juvenile shrimp (Group 1 - 10.9 ± 1.4 g, n = 10) with low-level GAV infection, eight gill filaments and eight pleopods were tested from each individual, and from another group of adult shrimp (Group 2 - 40.4 ± 2.3 g, n = 12) with higher-level GAV infection, 10 gill filaments, 10 pleopods and both lymphoid organ lobes were tested from each individual. For Group 1, 69/80 gill and 67/80 pleopod samples tested PCR-positive, and for Group 2, all samples tested PCR-positive. In some shrimp from each group, GAV detection levels among gill filaments or pleopods varied by up to ~3000-fold, highlighting the variability that is present in infection load among these tissues within individual shrimp. Statistical analyses used to determine the most sensitive and consistent tissue type to test identified no significant differences between mean GAV infection loads detected, either in gill or pleopod tissue, within each group (Group 1, p = 0.852; Group 2, p = 0. 146). Similarly, variability in GAV detection levels among individual gill filaments and pleopods did not differ between either tissue for each group (Group 1, p = 0.922; Group 2, p = 0.151). The mean GAV infection load (GAV RNA copies μg−1 TNA) detected in lymphoid organ lobes tested from Group 2 adult shrimp (5.96 × 107 ± 8.67 × 107 copies), was significantly higher (p < 0.0001) compared to either gill (1.37 × 105 ± 4.07 × 105 copies) or pleopod (6.97 × 104 ± 2.50 × 105 copies), confirming the value of testing lymphoid organ when destructive sampling is an option. When it is not an option, or when industrial scale high-throughput PCR screening for GAV is desired, the data reported here indicate that gill or pleopod tissue are equally suitable. However, processing more than a single gill filament or pleopod would most likely provide more accurate data on GAV presence and relative infection loads

Hypoxia-regulated glucose transporter Glut-1 may influence chemosensitivity to some alkylating agents: results of EORTC (First Translational Award) study of the relevance of tumour hypoxia to the outcome of chemotherapy in human tumour-derived xenografts.

Tumour hypoxia confers poor prognosis in a wide range of solid tumours, due to an increased malignancy, increased likelihood of metastasis and treatment resistance. Poorly oxygenated tumours are resistant to both radiation therapy and chemotherapy. However, although the link between radiation therapy and hypoxia is well established in a range of clinical studies, evidence of its influence on chemotherapy response is lacking. In this study, a panel of human tumour-derived xenografts that have been characterised previously for in vivo response to a large series of anti-cancer agents, and have been found to show chemosensitivities that correlate strongly with the parent tumour, were used to address this issue. Immunohistochemistry was carried out on formalin-fixed, paraffin-embedded sections of xenograft samples to detect expression of the intrinsic hypoxia marker Glut-1 and adducts of the bioreductive hypoxia marker pimonidazole. Glut-1 scores correlated significantly with T/C values for CCNU sensitivity (r = 0.439, P = 0.036, n = 23) and showed a borderline significant correlation with dacarbazine T/C (r = 0.405, P = 0.076, n = 20). However, there was no correlation between both Glut-1 and pimonidazole scores and T/C obtained for the bioreductive drug mitomycin C. The use of human tumour-derived xenografts offers a potentially useful way of using archival material to determine the influence of hypoxia and other tumour-microenvironmental factors on chemosensitivity without the direct use of human subjects