A Set of Multiresistant Isolates of Mycoplasma bovis Subtype ST-1 with a Variable Susceptibility to Quinolones Are Also Circulating in Spain.

Mycoplasma bovis (M. bovis) is one of the worldwide most important infectious agents involved in respiratory complex diseases (RCD). In Spain, the endemic presence of subtypes ST-2 and ST-3 with phenotypic differences linked to their susceptibility to fluoroquinolones opened the way to develop control strategies focused on previous diagnosis of the subtype and the use of directed therapies when M. bovis were involved in RCD. Surprisingly, microbiological studies conducted during 2023 evidenced for the first time the presence of Spanish isolates of a new polC-subtype, previously classified as ST-1, recovered from calves with respiratory symptoms and pneumonia in different areas of the country (n = 16). Curiously, the minimum inhibitory concentration (MIC) to a panel of antimicrobials revealed phenotypic differences between these ST-1 isolates when using fluoroquinolones (FLQ). There is no geographical correlation between MIC profiles even for a set of 8 isolates recovered from different animals in the same flock. Sequencing of 4 genes (gyrA, gyrB, parC and parE) encoding quinolone resistance-determining regions (QRDR) evidenced the presence of accumulate mutations in 2 ST-1 isolates with high FLQ MICs, but not in all them (n = 3), thus suggesting that, as previously recorded for ST-2 isolates, other mechanisms should be involved in the acquisition of resistence to these antimicrobials. Additionally, as previously detected in the Spanish ST-2 and ST-3, subtype ST-1 isolates are also resistant to macrolides or lincosamides.

Salmonella Excludes Salmonella in Poultry: Confirming an Old Paradigm Using Conventional and Barcode-Tagging Approaches.

Salmonella is one of the major foodborne bacterial pathogens, and the consumption of contaminated chicken meats isa primary route of Salmonella transmission into human food chains. However, the mechanism of Salmonella transmission within the chicken flock is not fully understood, including competition among Salmonella strains during chicken infection. The purpose of the present study was to evaluate the competitive exclusion (CE) between different or same Salmonella species consecutively challenged through the oral route. Two different approaches were used to evaluate the CE effect, including tracking Salmonella colonization by wild-type strains with difference in natural antibiotic resistance or DNA barcode-tagged isogenic strains. When day-of-hatch chicks were administered by wild-type S. Typhimurium (ST) on day 1, followed by infection on day 2 by S. Enteritidis (SE) or vice versa, most of the birds were colonized only by the first strains administered (82% by ST or 83% by SE). When similar experiments were performed using two different isogenic barcode-tagged SE strains, Illumina sequencing analysis of the barcode region showed that the first barcode-tagged strains administered were dominant strains, ranging from 92 to 99% of the Salmonella recovered from ceca. These results provide quantitative evidence supporting the CE theory that oral administration of Salmonella will produce predominant inhibition over the subsequent colonization of ceca by the following administration one day later by different or same Salmonella species. We also showed that the use of barcode-tagged isogenic strains in combination with deep profiling of barcodes by Illumina sequencing can serve as a quantitative method for studying complex dynamics of Salmonella infection, transmission and colonization in poultry.

The complete mitochondrial DNA of white shark (Carcharodon carcharias) from Isla Guadalupe, Mexico.

The Isla Guadalupe white shark mitochondrial structure is similar to the one previously reported for a white shark individual from Taiwan with a total length of 16,745 and 16,742 bp respectively; the base composition of the genomes was as follow A (30.60%), T (28.67%), C (26.86%) and G (13.87%), contains 13 protein-coding genes and 24 tRNA genes and the non-coding control region. The tRNA genes range from 70-72 bp. Gene order is the same as in other vertebrates and teleosts.

[Temporal and spatial variation of shorebirds in Barra de Navidad lagoon, Jalisco, during three non-breeding seasons]. / Variación temporal y espacial de aves playeras en la laguna Barra de Navidad, Jalisco, en tres temporadas no reproductivas.

Resident and migratory shorebirds inhabit different kinds of wetlands such as lagoons, rivers and seashores among others. In recent years, these areas have been importantly affected by urban, agriculture and touristic activities, such as the Barra de Navidad lagoon, for which little information is available to support conservation programs. The aim of this work was to describe shorebirds temporal and spatial distribution in Barra de Navidad lagoon during three non-breeding seasons (1999-2000, 2006-2007 and 2008-2009). For this, monthly censuses were performed from November-April with the purpose of registering all the shorebirds species. We were able to identify 19 shorebirds species (three residents and 16 winter visitors), of which Charadrius wilsonia, Limosa fedoa and Tringa semipalmata were the most abundant. The greater number of species was registered for November, December and March of the first and third seasons. The greater number of individuals was registered when birds were feeding during low tides, mainly in December, January and February of the first and third seasons. At low tide, there was a great number of species and individuals in zone C. This area had muddy substrates that were exposed during low tides and were used to feed. Barra de Navidad lagoon provided suitable habitats for feeding and resting for resident and migratory birds. Twelve of the 19 species were considered as priority within the Mexican bird conservation strategy. However, these habitats are threatened by human activities performed in the nearby areas of the lagoon that may have negative consequences for the distribution, abundance and conservation of these species.

Variación temporal y espacial de aves playeras en la laguna Barra de Navidad, Jalisco, en tres temporadas no reproductivas / Temporal and spatial variation of shorebirds in Barra de Navidad lagoon, Jalisco, during three non-breeding seasons

Resident and migratory shorebirds inhabit different kinds of wetlands such as lagoons, rivers and seashores among others. In recent years, these areas have been importantly affected by urban, agriculture and touristic activities, such as the Barra de Navidad lagoon, for which little information is available to support conservation programs. The aim of this work was to describe shorebirds temporal and spatial distribution in Barra de Navidad lagoon during three non-breeding seasons (1999-2000, 2006-2007 and 2008-2009). For this, monthly censuses were performed from November-April with the purpose of registering all the shorebirds species. We were able to identify 19 shorebirds species (three residents and 16 winter visitors), of which Charadrius wilsonia, Limosa fedoa and Tringa semipalmata were the most abundant. The greater number of species was registered for November, December and March of the first and third seasons. The greater number of individuals was registered when birds were feeding during low tides, mainly in December, January and February of the first and third seasons. At low tide, there was a great number of species and individuals in zone C. This area had muddy substrates that were exposed during low tides and were used to feed. Barra de Navidad lagoon provided suitable habitats for feeding and resting for resident and migratory birds. Twelve of the 19 species were considered as priority within the Mexican bird conservation strategy. However, these habitats are threatened by human activities performed in the nearby areas of the lagoon that may have negative consequences for the distribution, abundance and conservation of these species.

Hay un escaso conocimiento de las aves playeras en los humedales costeros de Jalisco, y en particular en la laguna Barra de Navidad. El presente trabajo contribuye al conocimiento de este grupo de aves y describe su distribución temporal y espacial en la laguna Barra de Navidad durante tres temporadas no reproductivas (1999-2000, 2006-2007 y 2008-2009). Se realizaron censos mensuales de noviembre-abril en las tres temporadas con el fin de registrar todas las especies de aves playeras. Se identificaron 19 especies (tres residentes y 16 visitantes de invierno), de las cuales Charadrius wilsonia, Limosa fedoa y Tringa semipalmata presentaron la mayor abundancia. Doce especies son consideradas como prioritarias en la “Estrategia para la Conservación y Manejo de las Aves Playeras y su Hábitat en México”. El mayor número de especies fue registrado en noviembre, diciembre y marzo en la primera y tercera temporada. El mayor número de individuos fue registrado alimentándose en marea baja, principalmente en diciembre, enero y febrero de la primera y tercera temporada. En marea baja hubo un mayor número de especies e individuos alimentándose en la zona C. Esta zona se caracterizó por tener sustratos lodosos expuestos durante marea baja y que fueron aprovechados por las aves para alimentarse. La laguna Barra de Navidad proporcionó hábitats de alimentación y descanso para las aves residentes y migratorias. Sin embargo, estos hábitats se ven amenazados por las actividades humanas realizadas dentro de la laguna, que sin duda tendrán consecuencias negativas para la distribución y abundancia de las aves playeras.

Relationship between MT1 melatonin receptor gene polymorphism and seasonal physiological responses in Ile-de-France ewes.

The gene encoding the MT1 melatonin receptor in sheep has a restriction fragment length polymorphism (RFLP) site to the MnlI enzyme whose incidence is associated to the expression of seasonality in several breeds. The aim of this study was to examine the relationship between this genetic marker and the physiological effects of MT1 receptor gene polymorphism on several seasonal functions in Ile-de-France ewes. The study was performed using 12 pairs of half-sib adult Ile-de-France ewes. Within each pair, ewes were selected on the basis of their genotype at the MnlI RFLP site: group +/+ and -/- (presence and absence of MnlI restriction site, respectively). No difference in the dates of the beginning, the end or the length of the breeding season was observed between groups during the two-year study. The seasonal changes in prolactin secretion were not different between groups. Similarly, wool growth rate and primary follicle activity, measured for one year, varied with the time of the year in the same way in the two groups. Our study therefore failed to show any relationship between MT1 polymorphism and reproductive seasonality in Ile-de-France ewes. This suggests that the influence of this polymorphism on the regulation of seasonal function is dependent upon the breed and/or environmental conditions. The MT1 polymorphism can explain only a small part of the genetic variability of seasonal functions and the implication of other genes must be investigated.