Subclinical intramammary infection does not affect bovine milk ethanol stability / Infecção intramamária subclínica não afeta a estabilidade do leite bovino

The present study hypothesized that intramammary infection (IMI) might reduce milk ethanol stability (MES), mainly when IMI is caused by major pathogens. Thus, this study evaluated the effect of IMI on bovine MES using a natural exposure experimental design. Ninety-four lactating cows from five dairy herds were selected once they were determined to have an IMI, based on milk bacteriological culturing with positive isolation and somatic cell count (SCC) > 200×103 cells/mL in two out of three composite milk samples collected during three consecutive weeks. After selection, cows were sampled a second time (within two weeks) for evaluation at mammary quarter level (n = 326): milk yield (kg/quarter/day), MES, composition (fat, protein, lactose, casein, total solids and solids-non-fat), and bacteriologic culture. The effect of subclinical mastitis on MES was tested by two models: 1) comparison of healthy vs. infected quarters; and 2) comparison of contralateral mammary quarter within cow. The only milk composition variable associated with MES was lactose (r = 0.18; P < 0.01). Subclinical IMI did not affect MES when the comparison was performed using both models (1 and 2). Likewise, MES did not change when infected quarters were sorted into two groups of pathogens (major, minor and infrequent; and contagious, environmental, minor and infrequent) and compared with healthy mammary quarters. Considering the results of both models, subclinical IMI did not affect MES of dairy cows.(AU)

Neste trabalho investigou-se a hipótese de que a infecção intramamária (IIM) poderia reduzir a estabilidade do leite ao etanol (ELA), principalmente quando a IIM é causada por agentes primários. Assim, em um experimento de exposição natural, foi avaliado o efeito da IIM sobre a ELA em bovinos. Noventa e quatro vacas em lactação de cinco rebanhos leiteiros foram selecionadas por apresentar IIM, segundo resultados de cultura bacteriológica de amostras compostas de leite (isolamento positivo) e contagem de células somáticas (CCS) > 200×103 células/mL em pelo menos duas de três coletas semanais consecutivas. Após essa seleção, as vacas foram amostradas pela segunda vez (dentro de duas semanas) para avaliação da IIM em amostras de leite coletadas por quarto mamário (n = 326): produção de leite (kg/quarto/dia), ELA, composição (gordura, proteína, lactose, caseína, sólidos totais e sólidos não gordurosos) e cultura bacteriológica. O efeito da mastite subclínica sobre a ELA foi testada por dois modelos: 1) comparação de quarto sadio versus infectado; e 2) comparação de quartos mamários contralaterais. A única variável de composição do leite associada à ELA foi a lactose (r = 0,18; P < 0,01). A IIM subclínica não afetou a ELA quando a comparação foi realizada utilizando-se os dois modelos (1 e 2); bem como a ELA não foi alterada quando os quartos infectados foram classificados em grupos de agentes patogênicos (primários, secundários e infrequentes; ou contagiosos, ambientais, secundários e infrequentes) e comparados com os quartos mamários sadios. Os resultados obtidos com os dois modelos empregados demonstraram que a IIM subclínica não afetou a ELA de vacas leiteiras.(AU)

Subclinical intramammary infection does not affect bovine milk ethanol stability / Infecção intramamária subclínica não afeta a estabilidade do leite bovino

The present study hypothesized that intramammary infection (IMI) might reduce milk ethanol stability (MES), mainly when IMI is caused by major pathogens. Thus, this study evaluated the effect of IMI on bovine MES using a natural exposure experimental design. Ninety-four lactating cows from five dairy herds were selected once they were determined to have an IMI, based on milk bacteriological culturing with positive isolation and somatic cell count (SCC) > 200×103 cells/mL in two out of three composite milk samples collected during three consecutive weeks. After selection, cows were sampled a second time (within two weeks) for evaluation at mammary quarter level (n = 326): milk yield (kg/quarter/day), MES, composition (fat, protein, lactose, casein, total solids and solids-non-fat), and bacteriologic culture. The effect of subclinical mastitis on MES was tested by two models: 1) comparison of healthy vs. infected quarters; and 2) comparison of contralateral mammary quarter within cow. The only milk composition variable associated with MES was lactose (r = 0.18; P < 0.01). Subclinical IMI did not affect MES when the comparison was performed using both models (1 and 2). Likewise, MES did not change when infected quarters were sorted into two groups of pathogens (major, minor and infrequent; and contagious, environmental, minor and infrequent) and compared with healthy mammary quarters. Considering the results of both models, subclinical IMI did not affect MES of dairy cows.(AU)

Neste trabalho investigou-se a hipótese de que a infecção intramamária (IIM) poderia reduzir a estabilidade do leite ao etanol (ELA), principalmente quando a IIM é causada por agentes primários. Assim, em um experimento de exposição natural, foi avaliado o efeito da IIM sobre a ELA em bovinos. Noventa e quatro vacas em lactação de cinco rebanhos leiteiros foram selecionadas por apresentar IIM, segundo resultados de cultura bacteriológica de amostras compostas de leite (isolamento positivo) e contagem de células somáticas (CCS) > 200×103 células/mL em pelo menos duas de três coletas semanais consecutivas. Após essa seleção, as vacas foram amostradas pela segunda vez (dentro de duas semanas) para avaliação da IIM em amostras de leite coletadas por quarto mamário (n = 326): produção de leite (kg/quarto/dia), ELA, composição (gordura, proteína, lactose, caseína, sólidos totais e sólidos não gordurosos) e cultura bacteriológica. O efeito da mastite subclínica sobre a ELA foi testada por dois modelos: 1) comparação de quarto sadio versus infectado; e 2) comparação de quartos mamários contralaterais. A única variável de composição do leite associada à ELA foi a lactose (r = 0,18; P < 0,01). A IIM subclínica não afetou a ELA quando a comparação foi realizada utilizando-se os dois modelos (1 e 2); bem como a ELA não foi alterada quando os quartos infectados foram classificados em grupos de agentes patogênicos (primários, secundários e infrequentes; ou contagiosos, ambientais, secundários e infrequentes) e comparados com os quartos mamários sadios. Os resultados obtidos com os dois modelos empregados demonstraram que a IIM subclínica não afetou a ELA de vacas leiteiras.(AU)

Identification of voltage-dependent Ca2+ channels in sea urchin sperm.

Functional evidence indicates that voltage-dependent Ca2+ (Cav) channels participate in sea urchin sperm motility and the acrosome reaction (AR), however, their molecular identity remains unknown. We have identified transcripts for two Ca2+ channel alpha1 subunits in sea urchin testis similar in sequence to Cav1.2 and Cav2.3. Antibodies against rat Cav1.2 and Cav2.3 channels differentially label proteins in the flagella and acrosome of mature sea urchin sperm. The Cav channel antagonists nifedipine and nimodipine, which inhibit the AR, diminish the intracellular Ca2+ elevation induced by a K+-induced depolarization in valinomycin-treated sperm. These findings reveal that Cav1.2 and Cav2.3 channels could participate in motility and/or the AR in sea urchin sperm.

Transient receptor potential (TRPC) channels in human sperm: expression, cellular localization and involvement in the regulation of flagellar motility.

Capacitative Ca(2+) entry is a process whereby the activation of Ca(2+) influx through the plasma membrane is triggered by depletion of intracellular Ca(2+) stores. Some transient receptor potential (TRPC) proteins have been proposed as candidates for capacitative Ca(2+) channels. Recent evidence indicates that capacitative Ca(2+) entry participates in the sperm acrosome reaction (AR), an exocytotic process necessary for fertilization. In addition, several TRPCs have been detected heterogeneously distributed in mouse sperm, suggesting that they may participate in other functions such as motility. Using reverse transcription-polymerase chain reaction (RT-PCR) analysis, RNA messengers for TRPC1, 3, 6 and 7 were found in human spermatogenic cells. Confocal indirect immunofluorescence revealed the presence of TRPC1, 3, 4 and 6 differentially localized in the human sperm, and immunogold transmission electron microscopy indicated that TRPC epitopes are mostly associated to the surface of the cells. Because all of them were detected in the flagellum, TRPC channel antagonists were tested in sperm motility using a computer-assisted assay. Our results provide what is to our knowledge the first evidence that these channels may influence human sperm motility.

Differences in both inositol 1,4,5-trisphosphate mass and inositol 1,4,5-trisphosphate receptors between normal and dystrophic skeletal muscle cell lines.

Human normal (RCMH) and Duchenne muscular dystrophy (RCDMD) cell lines, as well as newly developed normal and dystrophic murine cell lines, were used for the study of both changes in inositol 1,4,5-trisphosphate (IP3) mass and IP3 binding to receptors. Basal levels of IP3 were increased two- to threefold in dystrophic human and murine cell lines compared to normal cell lines. Potassium depolarization induced a time-dependent IP3 rise in normal human cells and cells of the myogenic mouse cell line (129CB3), which returned to their basal levels after 60 s. However, in the human dystrophic cell line (RCDMD), IP3 levels remained high up to 200 s after potassium depolarization. Expression of IP3 receptors was studied measuring specific binding of 3H-IP3 in the murine cell lines (normal 129CB3 and dystrophic mdx XLT 4-2). All the cell lines bind 3H-IP3 with relatively high affinity (Kd: between 40 and 100 nmol/L). IP3 receptors are concentrated in the nuclear fraction, and their density is significantly higher in dystrophic cells compared to normal. These findings together with high basal levels of IP3 mass suggest a possible role for this system in the deficiency of intracellular calcium regulation in Duchenne muscular dystrophy.

Inositol triphosphate receptors in sea urchin sperm.

Inositol 1,4,5-triphosphate (Ins(1,4,5)P3) is a second messenger that regulates Ca2+ channels in many important cell signalling pathways. In sea urchin sperm the outer investment of the egg triggers the acrosome reaction (AR) that involves Ins(1,4,5)P3 production and the opening of two Ca2+ channels. Here we have sought to identify a high-affinity Ins(1,4,5)P3 receptor in Strongylocentrotus purpuratus sperm. An Ins(1,4,5)P3 binding component was affinity-purified 12-fold from sperm extracts. It displayed similar characteristics to the Ins(1,4,5)P3 receptor from other sources: pH-dependent high affinity for Ins(1,4,5)P3 (KD = 261 nM), a tau1/2 of association and dissociation of 50 and 40 s, respectively, specificity (IC50 > 5 microM for Ins(1)P1, Ins(1,4)P2 and Ins(1,3,4,5)P4), and pharmacological sensitivity (10 and 100 microg heparin/ml inhibited 75% and 100% binding respectively). An antibody against the carboxy-terminal of the type I Ins(1,4,5)P3 receptor of somatic cells recognised a plasma membrane component in the sperm head and less intensely in the flagella. This antibody also recognised a 240 kDa band from isolated head plasma membranes, and weakly in flagellar membrane. This IP3 receptor-like protein may mediate the sustained uptake of Ca2+ through the second Ca2+ channel opened during the AR.