Association of milk microbiome with bovine mastitis before and after antibiotic therapy

Background and Aim

Mastitis is recognized as the most common disease in cattle and causes economic losses in the dairy industry. A number of opportunistic bacterial taxa have been identified as causative agents for this disease. Conventionally, antibiotics are used to treat mastitis; however, most bacteria are resistant to the majority of antibiotics. This study aimed to use molecular methods to identify milk microbiome patterns characteristic of mastitis that can help in the early diagnosis of this disease and in the development of new treatment strategies.

Materials and Methods

To evaluate the microbiome composition, we performed NGS sequencing of the 16S rRNA gene of the V3 region.

Results

An increase in the abundance of the bacterial genera Hymenobacter and Lachnospiraceae NK4A136 group is associated with the development of subclinical and clinical mastitis in dairy cows. These bacteria can be added to the list of markers used to detect mastitis in cows. Furthermore, a decrease in the abundance of Ralstonia, Lachnospiraceae NK3A20 group, Acetitomaculum, Massilia, and Atopostipes in cows with mastitis may indicate their role in maintaining a healthy milk microbiome. Antibiotics reduced the levels of Streptococcus in milk compared to those in the healthy group and cows before antibiotic treatment. Antibiotic therapy also contributed to an increase in the abundance of beneficial bacteria of the genus Asticcacaulis.

Conclusion

This study expands our understanding of the association between milk microbiota and mastitis.

Kinematic running resistance of an urban rail vehicle undercarriage: a study of the impact of wheel design

Urban railway vehicles are important means of transport in towns and cities due to their high capacity, power source, and low running resistance, which make them efficient for operation. Although these properties are considered advantages, there is still room for improvement in their operational efficiency. The main objective of this article is to investigate the impact of railway wheel design on the level of kinematic running resistance, which is expressed as the amount of mechanical energy losses during the interaction of wheels with rails. This research focuses on simulation computations of two variants of wheel design schemes: the traditional design scheme (TKS) and a perspective design scheme (PKS) characterized by a rotating flange independently of the wheel tread surface. Two undercarriage multibody models have been created, one with TKS and one with PKS, and simulation computations have been performed for running speeds of 10 km/h, 20 km/h, 30 km/h, and 40 km/h on track models in curves with radii of 20, 50, 100, 150, 200, and 250 m. The evaluated indicators affecting the level of mechanical energy losses were creep forces, slip velocities, and average power. The most important findings of this study are that the PKS design scheme resulted in lower values of all assessed parameters.

Studies on genes expression pattern of antioxidant enzymes and enzymes involved into the genetic information implementation in E.coli cells due to the antibiotic resistance against apramycin and cefatoxime

The emergence of antibiotic-resistant bacteria is considered a serious problem. The resistance of bacteria against antimicrobial substances becomes important in the repair systems for damage to DNA and RNA molecules. The role of the antioxidant system in the development of bacterial resistance against antibiotics is not yet practically studied. The article studied the expression regulation of the genes of antioxidant enzymes and enzymes involved in the genetic information in E. coli cells with the antibiotic resistance against apramycin and cefatoxime. The study was conducted on bacterial cells resistant against these two antibiotics. The genes blaOXA-1, blaSHV, blaTEM, mdtK, aadA1, aadA2, sat, strA, blaCTX, blaPER-2, tnpA, tnpR, intC1 and intC1c were identified in bacterial cell case. This indicates the presence of plasmids in bacteria with these genes, which provide bacterial resistance to apramycin and cefatoxime. It was established that during the formation of cefotaxime resistance, there was a sharp increase in the expression of the Cu, Zn superoxide dismutase gene: in comparison with the control group, the representation of its transcripts increased 141.04 times for cefotoxime and 155.42 times for apramycin. It has been established that during the formation of resistance to the studied antibiotics in E. coli, an increase in the expression of the end4 and end3 genes is observed. There is tendency toward an increase in the number of transcripts of the pol3E gene observed in the formation of resistance against cefotaxime and apromycin.

Upper limits on a stochastic background of gravitational waves

The Laser Interferometer Gravitational-Wave Observatory has performed a third science run with much improved sensitivities of all three interferometers. We present an analysis of approximately 200 hours of data acquired during this run, used to search for a stochastic background of gravitational radiation. We place upper bounds on the energy density stored as gravitational radiation for three different spectral power laws. For the flat spectrum, our limit of omega0 < 8.4 x 10(-4) in the 69-156 Hz band is approximately 10(5) times lower than the previous result in this frequency range.