农林科学最新文献

The mitochondrial gene cytochrome c oxidase subunit 1 (cox1) has long been suspected to be ineffective for species identification when employed alone. Some Lucilia (=Phaenicia) cuprina Wiedemann have mtDNA haplotypes closely resembling those of Lucilia sericata Meigen (Diptera: Calliphoridae), indicating paraphyly of L. cuprina with respect to L. sericata. Therefore, we evaluated the nuclear 28S rRNA and the mitochondrial cox1 genes to distinguish between L. cuprina and L. sericata using new DNA data from Northwest Africa. The current study provides the first evidence that L. cuprina occurs in Northwest Africa. The cox1 and the 28S genes were sequenced, and phylogenetic trees were constructed using the maximum likelihood method with 1000 bootstrap replicates. Sequencing yielded around 675 bp for cox1 and 633 bp for 28S. All the sequences were accurately identified using the BLASTn and submitted to GenBank. The 28S analysis confirmed the two species' mutual monophyly. In contrast, the cox1 analysis showed that L. cuprina is divided into two distinct clades, paraphyletic with respect to L. sericata. The 28S sequences clustered together do not exhibit any geographical consistency. Despite the paraphyletic relationship between L. sericata and the two forms of L. cuprina, mtDNA appears to be useful in differentiating between these two species. However, L. cuprina subspecies, L. cuprina cuprina (Wiedemann) and L. cuprina dorsalis Robineau-Desvoidy cannot be differentiated using the 28S and cox1 genes, nor can their distinctions be assumed based on their geographic locations, especially in regions where they are found in coexistence.

Runs of Homozygosity (ROH) are commonly used to quantify autozygosity/identity-by-descent (IBD) in an individual or population. However, the method's accuracy at the segment level in livestock populations has only been evaluated in a few studies. Thus, the aim of this study was to determine to what extent ROH are truly IBD and estimate the proportion of IBD segments that go undetected in a simulated livestock population. We simulated a population of randomly mating animals for 100 generations. The genome consisted of a single chromosome with a SNP density of either 46 or 92 SNPs per mega base (Mb). In addition, a set of founder markers tracing IBD was recorded. ROH were detected using four different parameter combinations. Using the two sets of markers, we calculated the true positive rate, power, and overall correlation between true (F_IBD) and estimated inbreeding (F_ROH). Additionally, a new measure for within-ROH inbreeding (F|ROH) was introduced and calculated the level of homozygosity within a ROH compared to the general expectation in the genome. The results indicate that ROH longer than 2 Mb are a reliable indicator of IBD, with the F|ROH being over 0.9 for all ROH lengths and parameter combinations. True positive rates only exceeded 0.9 consistently for ROH over 9 Mb, indicating that many of the identified ROH may be associated with common ancestors more ancient than the base population. The power was mainly controlled by the parameter stringency, that is, allowing for shorter ROH increased the power. The ROH-based individual measure of inbreeding F_ROH was highly correlated to F_IBD while also having regression coefficients close to 1 (i.e., a 1% variation in F_ROH corresponded to a 1% variation in F_IBD). Using stringent ROH parameters resulted in underestimation of the rate of inbreeding in the population. Increasing marker density improved predictions, including a higher true positive rate, power, higher correlations, and less underestimation of inbreeding rates.

This study aimed to evaluate the impact of different genomic prediction approaches on the predictive ability for meat tenderness in Nellore cattle. Phenotypic (n = 73,286), pedigree (n = 4,141,892) and genomic (n = 15,300) data from animals belonging to the genetic improvement program of the National Association of Breeders and Researchers (ANCP) were used. Six models were tested: (1) standard ssGBLUP (Single-step Genomic Best Linear Unbiased Prediction), considering direct additive genetic and residual effects as random, contemporary group (CG) as a fixed effect, and slaughter age as a linear and quadratic covariate; (2) Model 1 + ssGBLUP weighted with SNP effects from the first WssGWAS iteration; (3) Model 1 + ssGBLUP weighted with SNP effects from the second WssGWAS iteration; (4) Model 1 + body weight as a covariate; (5) Model 1 as a bi-trait model with body weight at 450 days (W450); (6) Model 1 as a multi-trait model with carcass traits: ribeye area (REA), backfat thickness (BFT) and rump fat thickness (RFT). Predictive ability was evaluated using linear regression, in which the dataset was divided into a complete and a partial subset (n = 374) dataset. Accuracy ranged from 0.04 (Models 2 and 3) to 0.37 (Model 6). Bias was low for all models, with Models 2 and 3 showing the least bias (-0.001). Model 6 showed the best performance in terms of accuracy and correlation (0.897), suggesting it was more effective in capturing genetic variability of meat tenderness, while reducing bias and increasing the precision of the estimates. Multi-trait models may offer more robust genomic predictions by leveraging trait correlations to increase prediction accuracy.

Procambarus acanthophorus is a freshwater crayfish species endemic to Mexico with high aquaculture potential. Monitoring genetic diversity during the early stages of domestication is crucial to avoid the erosion of adaptive potential and ensure the success of breeding programmes. This study analysed changes in genetic variability across four consecutive populations: a wild founder population (G0) and three captive-bred generations (G1, G2, G3), using five mitochondrial markers (COI, COII, COIII, tRNA-Asn/12S and D-loop) and one nuclear marker (elongation factor 2, EF-2). A total of 21 haplotypes were detected, with decreasing haplotype richness from G0 (n = 10) to G3 (n = 5), although haplotype and nucleotide diversity remained within moderate to high ranges (Hd = 0.65-0.90; π = 0.0020-0.0466), consistent with diversity levels reported in other early-stage domestication studies. AMOVA revealed that 68% of the total genetic variation was among generations, and pairwise Fst values confirmed progressive differentiation. These findings suggest that while some genetic erosion is occurring, the implemented breeding practices have preserved a substantial portion of genetic diversity during early domestication. This study provides a preliminary genetic baseline for the management of P. acanthophorus breeding programmes and underscores the need for continued monitoring using complementary nuclear markers.

Aliarcobacter butzleri is a Campylobacter-like bacteria associated with watery diarrhea in humans and is infrequently reported in nonhuman primate (NHP) populations. While clinical and microscopic features in humans are indistinguishable from Campylobacter spp. infection, descriptions of A. butzleri-associated colitis in NHP are lacking. Here, we describe the clinical and pathological features of diarrhea and colitis associated with A. butzleri in rhesus macaques using a retrospective approach. Over a 3-year period, A. butzleri was isolated from 10 macaques with diarrhea. Five of the 10 were submitted for necropsy and had features of chronic enterocolitis, consistent with existing literature. However, 40% (2/5) of the cases were characterized by ulcerative colitis, which has not previously been described as a feature of A. butzleri colitis. A. butzleri should be considered a differential diagnosis in cases of diarrhea and enterocolitis in captive rhesus macaques.

Alimentary mycosis is seldom reported in sloths. Through a multi-institutional retrospective study, we described the histological features of fungal infections within the digestive tract of sloths of the Bradypus and Choloepus genera. In addition, panfungal polymerase chain reaction (PCR) targeting the ITS-2 gene was performed in all cases to determine a specific etiology. We retrieved 11 cases of alimentary mycosis in 3 sloth species: Bradypus variegatus (n = 1), Choloepus hoffmanni (n = 7), and Choloepus didactylus (n = 3). Eight were free-ranging, whereas 3 were held in captivity. Nine were females and 8 were juveniles (ranging from 2 weeks to 2 years old). In 64% of the cases, the lesions were gastric in the muscular portion of the prepyloric stomach. In the other animals, the lesions were located in the tongue and/or esophagus. Pustules, erosions, ulcers, and hyperkeratosis within the keratinoid layer with intralesional yeast, pseudohyphae, and hyphae characterized alimentary mycotic infections. Panfungal PCR identified Trichosporon asahii infection in 45% (5/11) of the cases, from gastric, esophageal, and lingual lesions, and Penicillium sp. and Wallemia mellicola in a gastric lesion in 1 case each. Candida sp. infection was not confirmed in any of the cases. Trichosporon asahii has overlapping histological features with Candida and poses a diagnostic challenge when conventional culture or molecular methods are unavailable. Trichosporonosis is a differential diagnosis in cases of fungal alimentary lesions in sloths. Predisposing factors for alimentary mycosis in sloths include age (younger animals), canine distemper virus co-infection, late pregnancy, and chronic antibiotic use.

Seven cutaneous mast cell tumors were identified in 6 geriatric California sea lions (Zalophus californianus). All tumors were within the dermis and grossly appeared as single, or in one case two, less than 1-cm-diameter, well-circumscribed, raised nodules. The majority (6/7) of the neoplasms occurred near mucocutaneous junctions (eyelid, lip, or anus). The mast cell tumors were composed of round cells arranged in sheets with poorly granulated cytoplasm or an absence of cytoplasmic granules in routine hematoxylin and eosin-stained sections. Cytology (n = 1) showed adequate staining of mast cell granules with Diff-Quik and Wright-Giemsa stains. Immunohistochemistry for cKIT revealed cytoplasmic to membranous immunoreactivity in all tumors. Giemsa staining for metachromatic granules was inconsistent. No local recurrence or metastasis has been observed in the 5 living individuals with follow-up periods ranging from 6 to 42 months. Given these findings, similar poorly granulated mast cell tumors in geriatric California sea lions are suspected to have biologically benign behavior.

The vacuole formation (VF) rat is an autosomal recessive myelin mutant characterized by generalized tremor, hypomyelination, and periaxonal VF of the central nervous system. We previously identified a nonsense mutation in the DOP1 leucine zipper-like protein A (Dop1a, also known as Dopey1) gene located on rat chromosome 8. In this study, we investigated the kinetics of oligodendrocyte progenitor cells (OPCs) and oligodendrocytes by assessing the expression patterns of transcription factors that are involved in oligodendrocyte development. The number of small, round oligodendrocytes lacking distinct cellular processes, immunolabeled with anti-adenomatous polyposis coli (APC, clone CC1) antibody, was increased in the spinal cords of the VF rats, suggesting a disrupted maturation of oligodendrocytes. In addition, the terminal differentiation and maturation of OPCs into myelinating mature oligodendrocytes may be impaired and compensatory myelination largely could fail in the VF rat. Our findings also demonstrated that the DOP1A protein is expressed in OPCs as well as mature oligodendrocytes. Finally, the intracellular trafficking of myelin basic protein (Mbp) mRNAs may be disrupted in oligodendrocytes of the VF rats. Our data suggested that DOP1A dysfunction causes impaired differentiation and maturation of oligodendrocyte-lineage cells, resulting in hypomyelination and an impaired compensatory myelination.

Urine irritant contact dermatitis is a clinically well-recognized but poorly documented condition in small animals. This study aims to systematically summarize the clinical and histopathological features of canine and feline urine scalding. Twelve cases, 10 dogs and 2 cats, were identified and included in a retrospective study of medical records and histology samples. All animals had histories of urinary incontinence with urinary problems (ectopic ureters, urolithiasis, urinary tract infection, sphincter mechanism incompetence, etc.) or a genital conformational issue with concurrent urine scalding. Gross lesions varied and included white papules/plaques, discrete nodules, and overt ulcers that localized to perigenital areas and/or involve the abdomen, inguinal areas, and proximal legs. The hallmark histopathological changes were locally extensive epithelial hyperplasia with marked spongiosis (intracellular edema) of the granular and spinous layers, diffuse parakeratosis, and variable degrees of erosion to ulceration with secondary bacterial infection and necrosis. This report summarizes the clinical and histopathological findings in urine scalding and highlights the importance of the clinical history, presentation, and lesion distribution to achieve the correct diagnosis. In the absence of a history or awareness by the pathologist of this unique histopathological pattern, urine scalding could easily be misdiagnosed.