Capacity of adherence, invasion and intracellular survival of Streptococcus uberis biofilm-forming strains.

AIM: Nine Streptococcus uberis strains with different biofilm-forming profiles in relation to their capacity of adherence and invasion to MAC-T cell lines were examined. Additionally, virulence genes were also linked to adherence and invasion. METHODS AND RESULTS: All S. uberis were able to adhere and invade the cells at different levels. UB56 strain showed the highest percentage of internalization (3.65%) and presented a moderate level of adhesion (4.6 × 106 ). In contrast, UB152, the most adherent strain (8.7 × 106 ) showed a low capacity to internalize (0.65%). Eight strains were able to persist intracellularly over 96 h regardless of their adherence or invasion level. Statistical analysis between biofilm-forming ability and the adhesion capacity showed no significant differences. Presence of virulence genes involved in the adhesion process (gapC, hasABC, lbp, pauA and sua) showed that the strains harboured different genes and seven patterns could be observed. CONCLUSION: Statistical analysis showed no correlation between the virulence gene patterns and the adhesion capacity or the percentage of internalization. Biofilm-forming ability did not influence the invasion capacity. Likewise, adherence and invasion capacity may be strain dependent. SIGNIFICANCE AND IMPACT OF THE STUDY: Findings from this study provide new insights on biofilm and invasion capacity of S. uberis strains. Results could help to design adequate control strategies.

Effect of prepubertal nutrition on cellular apoptosis and proliferation in at term placenta of Anglo-Nubian goats.

The aim of this study was to evaluate the effect of feed restriction with or without monensin supplementation, followed by a re-feeding period on cellular apoptosis and proliferation in at term placenta of Anglo-Nubian goats. To evaluate the induction of apoptosis through the intrinsic pathway, proteins Bax and Bcl-2 were determinated. The apoptosis was related with the cell proliferation indices through Ki67 determination. The treatments were applied for 250 days and were (a) ad libitum feeding (control; n = 5); (b) restricted feeding at 70% of control (restricted; n = 7); and (c) restricted with monensin supplementation (monensin; n = 7). After treatments, all the animals were fed to support their requirements. After parturition, 27 placentas were gathered. The placental cellular structure was studied by high-resolution light microscopy and transmission electron microscopy; the cellular proliferation was determined by Ki67 index, and Bax and Bcl-2 proteins were localized by immunohistochemical analysis. Differences in cell proliferation through the Ki67 index were found in monensin group placentas. Monensin supplementation stimulated the placental cell proliferation reversing the effect of feed restriction during the peripuberal period. A significant increase of Bcl-2 in placentas of restricted group was found, and it would provide a protective effect on the placental structure. A lack of the Bcl-2 protective effect was observed in control and monensin group placentas, probably meaning that the observed apoptosis would be induced through the intrinsic signalling pathway. A balance between apoptosis and cell proliferation is necessary to maintain tissue homoeostasis during caprine placental development.

Apoptosis and cell proliferation in porcine placental vascularization.

The placenta is a highly vascularized organ, indispensable tothe transfer of nutrients to the growing fetuses. During gestation, there exists an expansion of the placental vascular network through active angiogenesis. The aim of this research was to study cell proliferation and apoptosis through high resolution light microscopy (HRLM) and transmission electron microscopy (TEM) ultrastructure, immunohistochemistry for Ki67and caspase-3, determination of placental vascular area,and TUNEL assay. Crossbred sows placental tissues from approximately 30±2(n=5), 40±2(n=5), 60±2 (n=5), 80±2(n=5), 90±2(n=5) and 114±2(n=5) days of gestation were used. The evaluation of cell proliferation showed the highest%Ki67 values on days 30±2 and 80±2 of pregnancy. Caspase-3 expressed the highest value on day 30±2, while the highest apoptotic indexes were found on days30±2 and 90±2. The placental vascular area was higher on day 80±2 of pregnancy. According to our results, an active vascular cell remodeling by a caspase-3 dependent apoptosis seems to be present in early pregnancy. The increase in the vascular area on day 80±2 would be the result of the intense vascular cell proliferation detected with Ki67. Further studies are needed to understand the complex processes of angiogenesis, cell proliferation and apoptosis that interact in the placenta during porcine gestation.

Actividad sérica del Factor Precoz de Preñez (EPF) durante la gestación en porcinos / Serum Early Pregnancy Factor (EPF) activity during gestation in sows

Para lograr una preñez exitosa es necesario un reconocimiento inmunológico entre la madre y el feto. Tal reconocimiento se realizaría a través de señales como el Factor precoz de preñez (EPF) y de hormonas como la progesterona, que se sintetizan muy tempranamente y poseen actividad inmunosupresora. En este trabajo, se estudió el comportamiento de ambas sustancias durante toda la gestación en porcinos. Se investigó en el suero de 5 cerdas, la actividad de EPF y la concentración de progesterona en estro y en los días 3, 7, 14, 21, 28, 45, 75, 90 y 110 post-servicio. La actividad del EPF mostró un perfil bifásico. Durante el primer tercio de la gestación, en todos los casos el valor máximo de progesterona, apareció 7 días después de los valores máximos de la actividad EPF. Por el contrario, en los dos tercios restantes, los valores máximos de EPF coinciden con los valores máximos de progesterona. De los resultados obtenidos podemos concluir que el EPF sería un buen indicador de fertilización y trazador de viabilidad embrionaria.