Publications by authors named "Kristen Behrens"

The process of sexual development in animals is modulated by a variety of mechanisms. Some species respond to environmental cues, while, in others, sex determination is thought to be controlled by a single 'master regulator' gene. However, many animals respond to a combination of environmental cues (e.

View Article and Find Full Text PDF

Objective: To describe the complications, surgical outcome, and prognosis associated with cystotomies in guinea pigs.

Methods: A retrospective review of medical records of guinea pigs undergoing cystotomy for uroliths or urethroliths between 2010 and 2023.

Results: 25 guinea pigs were included in the study.

View Article and Find Full Text PDF

Advances in genome sequencing have greatly accelerated the identification of sex chromosomes in a variety of species. Many of these species have experienced structural rearrangements that reduce recombination between the sex chromosomes, allowing the accumulation of sequence differences over many megabases. Identification of the genes that are responsible for sex determination within these sometimes large regions has proved difficult.

View Article and Find Full Text PDF

Reproductive behaviors differ across species, but the mechanisms that control variation in mating and parental care systems remain unclear. In many animal species, pheromones guide mating and parental care. However, it is not well understood how vertebrate pheromone signaling evolution can lead to new reproductive behavior strategies.

View Article and Find Full Text PDF

A 3-year-old castrated male golden retriever was presented for evaluation of 2 cutaneous masses along the abdominal midline and a 6-month history of progressive lethargy and inappetence. Two years earlier, the dog underwent a gastrotomy to retrieve a foreign object and recovered uneventfully. Fluid aspirated from the lesions was culture-negative for aerobic and anaerobic bacterial growth.

View Article and Find Full Text PDF

African cichlid fishes are known for their high rates of phenotypic evolution. A rapid rate of diversification is apparent also in the diversity of their sex chromosomes. To date, sex determiners have been identified on 18 of 22 chromosomes in the standard karyotype.

View Article and Find Full Text PDF

Sex chromosome replacement is frequent in many vertebrate clades, including fish, frogs, and lizards. In order to understand the mechanisms responsible for sex chromosome turnover and the early stages of sex chromosome divergence, it is necessary to study lineages with recently evolved sex chromosomes. Here we examine sex chromosome evolution in a group of African cichlid fishes (tribe Tropheini) which began to diverge from one another less than 4 MYA.

View Article and Find Full Text PDF

Background: Storage of samples may be necessary prior to testing drug levels in certain study designs; however, the effect of storage duration on measured drug levels is not known for all drugs.

Objectives: The objective of this study was to evaluate the stability of carprofen in canine plasma when stored at -80°C for 6 months.

Methods: Six healthy dogs were enrolled (1-10 years old, 17-35 kg) and received compounded carprofen at 2.

View Article and Find Full Text PDF

Sex determining loci have been described on at least 12 of 22 chromosomes in East African cichlid fishes, indicating a high rate of sex chromosome turnover. To better understand the rates and patterns of sex chromosome replacement, we used new methods to characterize the sex chromosomes of the cichlid tribe Cyprichromini from Lake Tanganyika. Our k-mer based methods successfully identified sex-linked polymorphisms without the need for a reference genome.

View Article and Find Full Text PDF

African cichlid fishes harbor an extraordinary diversity of sex-chromosome systems. Within just one lineage, the tribe Haplochromini, at least 6 unique sex-chromosome systems have been identified. Here we focus on characterizing sex chromosomes in cichlids from the Lake Victoria basin.

View Article and Find Full Text PDF

Depth separation is a proposed driver of speciation in marine fishes, with marine rockfish (genus Sebastes) providing a potentially informative study system. Sebastes rockfishes are commercially and ecologically important. This genus encompasses more than one hundred species and the ecological and morphological variance between these species provides opportunity for identifying speciation-driving adaptations, particularly along a depth gradient.

View Article and Find Full Text PDF