Comparação de métodos para avaliação de beta-hidroxibutirato em ovelhas / Comparison of methods for evaluation of beta-hydroxybutyrate in ewes

Atualmente o uso de sensores portáteis para mensuração de corpos cetônicos está padronizado e difundido na rotina clínica, contudo estudos em ovinos são escassos. Assim, a presente pesquisa objetivou avaliar a acurácia dos sensores portáteis de uso humano e de uso veterinário para a determinação de beta-hidroxibutirato (BHB) em ovelhas no final da gestação e no pós-parto recente. Foram utilizadas 37 amostras de sangue provenientes de nove ovelhas mestiças Corriedale. A determinação bioquímica de BHB no soro, considerada como o padrão-ouro, foi realizada utilizando-se metodologia enzimática colorimétrica. A média obtida na bioquímica sérica foi de 0,497mmol/L; no sensor de uso humano, a média foi igual a 0,537mmol/L, enquanto no sensor de uso veterinário foi de 0,751mmol/L. Foi verificada alta correlação entre o dosímetro de uso humano e o padrão-ouro (r=0,93, P<0,001). A média do aparelho de uso veterinário diferiu das demais (51%; P<0,05), superestimando os resultados em ovelhas. As medições obtidas no aparelho veterinário também apresentaram menor precisão e veracidade. Concluiu-se que o sensor portátil de uso humano é mais acurado e mais preciso no diagnóstico precoce de toxemia da gestação em ovelhas.

Currently the use of portable sensors for measuring ketone bodies is standardized and diffused in the clinical routine, however, studies in sheep are scarce. Therefore, the present study aimed to evaluate the accuracy of the human portable sensor and the veterinary portable sensor for the determination of beta-hydroxybutyrate (BHB) in sheep at the end of gestation and postpartum. We used 37 samples of blood from nine crossbred Corriedale sheep. Biochemical determination of serum BHB, considered gold standard, was performed using colorimetric enzymatic methodology. The mean serum biochemistry was 0.497mmol/L, in the human sensor the mean was 0.537mmol/L, while in the veterinary sensor it was 0.751mmol/L. A high correlation was verified between the dosimeter for human use and the gold standard (r= 0.93, P< 0.001). The mean of the veterinary apparatus differed from the others, being 51% (P< 0,05), higher than the standard, that is, it was less accurate and had lower veracity, overestimating the results in sheep. It was concluded that the portable sensor for human use is more accurate and accurate in the early diagnosis of toxemia of pregnancy in sheep.

Methanogenesis produces strong 13C enrichment in stromatolites of Lagoa Salgada, Brazil: a modern analogue for Palaeo-/Neoproterozoic stromatolites?

Holocene stromatolites characterized by unusually positive inorganic δ(13) CPDB values (i.e. up to +16‰) are present in Lagoa Salgada, a seasonally brackish to hypersaline lagoon near Rio de Janeiro (Brazil). Such positive values cannot be explained by phototrophic fixation of CO2 alone, and they suggest that methanogenesis was a dominating process during the growth of the stromatolites. Indeed, up to 5 mm methane was measured in the porewater. The archaeal membrane lipid archaeol showing δ(13) C values between -15 and 0‰ suggests that archaea are present and producing methane in the modern lagoon sediment. Moreover, (13) C-depleted hopanoids diplopterol and 3ß-methylated C32 17ß(H),21ß(H)-hopanoic acid (both -40‰) are preserved in lagoon sediments and are most likely derived from aerobic methanotrophic bacteria thriving in the methane-enriched water column. Loss of isotopically light methane through the water column would explain the residual (13) C-enriched pool of dissolved inorganic carbon from where the carbonate constituting the stromatolites precipitated. The predominance of methanogenic archaea in the lagoon is most likely a result of sulphate limitation, suppressing the activity of sulphate-reducing bacteria under brackish conditions in a seasonally humid tropical environment. Indeed, sulphate-reduction activity is very low in the modern sediments. In absence of an efficient carbonate-inducing metabolic process, we propose that stromatolite formation in Lagoa Salgada was abiotically induced, while the (13) C-enriched organic and inorganic carbon pools are due to methanogenesis. Unusually, (13) C-enriched stromatolitic deposits also appear in the geological record of prolonged periods in the Palaeo- and Neoproterozoic. Lagoa Salgada represents a possible modern analogue to conditions that may have been widespread in the Proterozoic, at times when low sulphate concentrations in sea water allowed methanogens to prevail over sulphate-reducing bacteria.

Oxidation of Fe(II) leads to increased C-2 methylation of pentacyclic triterpenoids in the anoxygenic phototrophic bacterium Rhodopseudomonas palustris strain TIE-1.

Hopanoids are among the most widespread biomarkers of bacteria that are used as indicators for past and present bacterial activity. Our understanding of the production, function, and distribution of hopanoids in bacteria has improved greatly, partly due to genetic, culture-independent studies. Culture-based studies are important to determine hopanoid function and the environmental conditions under which these compounds are produced. This study compares the lipid inventory of Rhodopseudomonas palustris strain TIE-1 under anoxic photoautotrophic conditions using either H2 or Fe(II) as electron donor. The high amount to which adenosylhopane is produced irrespective of the used electron donor suggests a specific function of this compound rather than its exclusive role as an intermediate in bacteriohopanepolyol biosynthesis. C-2 methylated hopanoids and tetrahymanol account for as much as 59% of the respective C-2 methylated/non-methylated homologs during growth with Fe(II) as electron donor, as compared with 24% C-2 methylation for growth with H2 . This observation reveals that C-2 methylated hopanoids have a specific function and are preferentially synthesized in response to elevated Fe(II) concentrations. The presence of C-2 methylated pentacyclic triterpenoids has commonly been used as a biosignature for the interpretation of paleoenvironments. These new findings suggest that increased C-2 methylation may indicate anoxic ferrous conditions, in addition to other environmental stressors that have been previously reported.

Microbial methane turnover at Marmara Sea cold seeps: a combined 16S rRNA and lipid biomarker investigation.

Lipid biomarkers and their stable carbon isotopic composition, as well as 16S rRNA gene sequences, were investigated in sediment cores from active seepage zones in the Sea of Marmara (Turkey) located on the active North Anatolian Fault, to assess processes associated with methane turnover by indigenous microbial communities. Diagnostic (13) C-depleted archaeal lipids of anaerobic methane oxidizers were only found in one core from the South of Çinarcik Basin and consist mainly of archaeol, sn-2 hydroxyarchaeol and various unsaturated pentamethylicosenes. Concurrently, abundant fatty acids (FAs) and a substantial amount of monoalkylglycerolethers (MAGEs), assigned to sulphate-reducing bacteria, were detected with strong (13) C-depletions. Both microbial lipids and their δ(13) C values suggest that anaerobic oxidation of methane with sulphate reduction (AOM/SR) occurs, specially in the 10- to 12-cm depth interval. Lipid biomarker results accompanied by 16S rRNA-based microbial diversity analyses showed that ANME-2 (ANME-2a and -2c) archaea and Desulfosarcina/Desulfococcus and Desulfobulbus deltaproteobacterial clades are the major AOM assemblages, which indicate a shallow AOM community at high methane flux. Apart from the typical AOM lipid biomarker pattern, a (13) C-depleted diunsaturated hydrocarbon, identified as 7,14-tricosadiene, occurred in the inferred maximum AOM interval at 10-12 cm depth. Its isotopic fingerprint implies that its microbial precursor occurs in close association with the AOM communities. Interestingly, the presence of 7,14-tricosadiene coincides with the presence of the so-far uncultured bacterial Candidate Division JS1, often detected in AOM areas. We propose the hypothesis that the JS1 bacterial group could be the potential source of (13) C-depleted tricosadiene. Future testing of this hypothesis is essential to fully determine the role of this bacterial group in AOM.

Bacterial formation of phosphatic laminites off Peru.

Authigenic phosphatic laminites enclosed in phosphorite crusts from the shelf off Peru (10 degrees 01' S and 10 degrees 24' S) consist of carbonate fluorapatite layers, which contain abundant sulfide minerals including pyrite (FeS(2)) and sphalerite (ZnS). Low delta(34)S(pyrite) values (average -28.8 per thousand) agree with bacterial sulfate reduction and subsequent pyrite formation. Stable sulfur isotopic compositions of sulfate bound in carbonate fluorapatite are lower than that of sulfate from ambient sea water, suggesting bacterial reoxidation of sulfide by sulfide-oxidizing bacteria. The release of phosphorus and subsequent formation of the autochthonous phosphatic laminites are apparently caused by the activity of sulfate-reducing bacteria and associated sulfide-oxidizing bacteria. Following an extraction-phosphorite dissolution-extraction procedure, molecular fossils of sulfate-reducing bacteria (mono-O-alkyl glycerol ethers, di-O-alkyl glycerol ethers, as well as the short-chain branched fatty acids i/ai-C(15:0), i/ai-C(17:0) and 10MeC(16:0)) are found to be among the most abundant compounds. The fact that these molecular fossils of sulfate-reducing bacteria are distinctly more abundant after dissolution of the phosphatic laminite reveals that the lipids are tightly bound to the mineral lattice of carbonate fluorapatite. Moreover, compared with the autochthonous laminite, molecular fossils of sulfate-reducing bacteria are: (1) significantly less abundant and (2) not as tightly bound to the mineral lattice in the other, allochthonous facies of the Peruvian crusts consisting of phosphatic coated grains. These observations confirm the importance of sulfate-reducing bacteria in the formation of the phosphatic laminite. Model calculations highlight that organic matter degradation by sulfate-reducing bacteria has the potential to liberate sufficient phosphorus for phosphogenesis.

Teores de cloretos, lactose e índice cloretos/lactose na secreção láctea de bovinos da raça Jersey no primeiro mês da lactação / Chloride and lactose contents and chloride/lactose ratio in milk from Jersey cows in the first month of lactation

Avaliou-se a influência do período colostral nos teores lácteos de cloretos, lactose e do índice cloretos/lactose. Foram colhidas 418 amostras de leite provenientes de glândulas mamárias sadias, e que não apresentavam crescimento bacteriano ao exame microbiológico, de 127 vacas da raça Jersey. As amostras foram distribuídas em oito grupos: 0 ┤1/2 dia; 1/2 ┤1 dia; 1 ┤2 dias; 2 ┤3 dias; 3 ┤5 dias; 5 ┤7 dias; 7 ┤15 dias; 15 ┤30 dias em lactação. Nas amostras, colhidas antes da ordenha, foram determinados os valores de cloretos, por titulação colorimétrica, e de lactose, por radiação infravermelho, e calculou-se o índice cloretos/lactose. Nas primeiras 24 horas da lactação, observou-se abrupta diminuição no teor lácteo de cloretos e do índice cloretos/lactose, associada com o aumento no teor lácteo de lactose. A transição da secreção de colostro para leite em relação ao teor de cloretos e lactose e ao índice cloretos/lactose na secreção láctea ocorreu na primeira semana da lactação, a partir do terceiro dia da lactação para o valor de cloretos e para a relação cloretos/lactose e a partir do quarto dia da lactação para o teor de lactose. Recomenda-se, nas primeiras 24 horas da lactação, a adoção dos seguintes limites de normalidade: cloretos, <173,4mg/dL; lactose >3,94g/dL e índice cloretos/lactose, <6,11 por cento. Entre o segundo e o sétimo dia da lactação (transição de colostro para leite), indicamse os seguintes limites: cloretos <125,9mg/dL; lactose, >4,03g/dL e índice cloretos/lactose <3,54.

In order to assess the influence of the colostral period on chloride and lactose levels and on the chloride/lactose ratio, 419 milk samples from 127 Jersey cows were analyzed. The samples were collected from healthy udders that did not present any bacterial growth in the microbiological examination. Cows were distributed into eight groups as follows: 0 ┤1/2 day; 1/2 ┤1 day; 1 ┤2 days; 2 ┤3 days; 3 ┤5 days; 5 ┤7 days; 7 ┤15 days; 15 ┤30 days of lactation. The samples were collected before milking to analyze the levels of chloride by colorimetric titration, lactose by infrared radiation, and to determine the chloride/lactose ratio. In the first 24 hours after partition, there was an abrupt reduction in chloride levels as well in chloride/ lactose ratio, associated with an increase in lactose levels. It was observed that the transition of the secretion from colostrum to milk, regarding chloride and lactose levels and chloride/lactose ratio occurred during the first week of lactation: from the 3rd day of lactation for chloride and chloride/lactose ratio and from 4th for the lactose levels. It is recommended the use the following thresholds as normal ranges for the first 24 hours of lactation: chloride <173.4mg/dL; lactose >3.94g/dL, and chloride/lactose ratio <6.11 percent; and between 2nd and 7th days of lactation (transition from colostrum to milk), it was suggested the use of the following values: chloride <125.9mg/dL; lactose >4.03g/dL and chloride/lactose ratio <3.54.