Time and sequence of the replacement of the deciduous by the permanent dentition in dogs and its applicability for age estimation

This study investigated the influence of several covariates on the time and sequence of permanent dentition emergence following exfoliation of the deciduous teeth in puppies. The aim was to determine whether the emergence of permanent dentition can be used to assess whether a puppy that is traded across borders in the EU has reached the legally required minimum age of 15 weeks. The events were evaluated in a longitudinal study, with some cross-sectional observations, of 440 puppies belonging to 82 breeds. No significant differences were found between the left and right sides of a puppy's dentition nor between male and female puppies. Breed size and skull type had a significant impact: both the appearance and the completion of tooth eruption occurred considerably later in small or toy breeds and brachycephalic skull type breeds. The sequence of emergence differed little between maxillary or mandibular quadrants or between breeds. The first emerging elements were the maxillary first premolars or first incisors or the mandibular first incisors. The emergence of a permanent tooth usually occurred within 3 days before or after exfoliation of its precursor, except for the canines, which demonstrated a wider tooth replacement interval. This study presents standards for age assessment based on the emergence of permanent dentition for breeds of different sizes, using median ages or cumulative emergence percentages. However, the legal age determination of puppies with an assumed age of 15 weeks cannot be performed based on permanent dentition emergence, as this occurred at a later age in a large proportion of dogs (at least 95%) in our studied population. The probability of being at least 15 weeks old when at least one maxillary tooth has emerged was at least 72.25%, depending on breed size.

Dynamic Immune Response to Vibriosis in Pacific Oyster Crassostrea gigas Larvae during the Infection Process as Supported by Accurate Positioning of GFP-Tagged Vibrio Strains

As the immune system is not fully developed during the larval stage, hatchery culture of bivalve larvae is characterized by frequent mass mortality caused by bacterial pathogens, especially Vibrio spp. However, the knowledge is limited to the pathogenesis of vibriosis in oyster larvae, while the immune response to pathogenic microorganisms in this early life stage is still far from being fully elucidated. In this study, we combined green fluorescent protein (GFP)-tagging, histological and transcriptomic analyses to clarify the pathogenesis of experimental vibriosis and the mechanisms used by the host Pacific oyster Crassostrea gigas larvae to resist infection. The Vibrio strains first colonized the digestive system and rapidly proliferated, while only the transcription level of IκB kinase (IKK) and nuclear factor κB (NF-κB) associated with signaling transduction were up-regulated in oyster at 18 h post challenge (hpc). The mRNA levels for integrin β-1, peroxinectin, and heat shock protein 70 (HSP70), which are associated with phagocytosis, cell adhesion, and cytoprotection, were not upregulated until 30 hpc when the necrosis already happened in the larval digestive system. This suggested that the immunity in the early stages of C. gigas is not strong enough to prevent vibriosis and future research may focus on the strengthening of the gastrointestinal immune ability to defend vibriosis in bivalve larvae.

A Study of Carry-Over and Histopathological Effects after Chronic Dietary Intake of Citrinin in Pigs, Broiler Chickens and Laying Hens

Citrinin (CIT) is a polyketide mycotoxin occurring in a variety of food and feedstuff, among which cereal grains are the most important contaminated source. Pigs and poultry are important livestock animals frequently exposed to mycotoxins, including CIT. Concerns are rising related to the toxic, and especially the potential nephrotoxic, properties of CIT. The purpose of this study was to clarify the histopathological effects on kidneys, liver, jejunum and duodenum of pigs, broiler chickens and laying hens receiving CIT contaminated feed. During 3 weeks, pigs (n = 16) were exposed to feed containing 1 mg CIT/kg feed or to control feed (n = 4), while 2 groups of broiler chickens and laying hens (n = 8 per group) received 0.1 mg CIT/kg feed (lower dose group) and 3 or 3.5 mg CIT/kg feed (higher dose group), respectively, or control feed (n = 4). CIT concentrations were quantified in plasma, kidneys, liver, muscle and eggs using a validated ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method. Kidneys, liver, duodenum and jejunum were evaluated histologically using light microscopy, while the kidneys were further examined using transmission electron microscopy (TEM). Histopathology did not reveal major abnormalities at the given contamination levels. However, a significant increase of swollen and degenerated mitochondria in renal cortical cells from all test groups were observed (p < 0.05). These observations could be related to oxidative stress, which is the major mechanism of CIT toxicity. Residues of CIT were detected in all collected tissues, except for muscle and egg white from layers in the lowest dose group, and egg white from layers in the highest dose group. CIT concentrations in plasma ranged between 0.1 (laying hens in lower dose group) and 20.8 ng/mL (pigs). In tissues, CIT concentrations ranged from 0.6 (muscle) to 20.3 µg/kg (liver) in pigs, while concentrations in chickens ranged from 0.1 (muscle) to 70.2 µg/kg (liver). Carry-over ratios from feed to edible tissues were between 0.1 and 2% in pigs, and between 0.1 and 6.9% in chickens, suggesting a low contribution of pig and poultry tissue-derived products towards the total dietary CIT intake for humans.

Identification of a microscopically selected microorganism in milk samples

Identification of unwanted microbial contaminants microscopically observed in food products is challenging due to their low abundance in a complex matrix, quite often containing other microorganisms. Therefore, a selective identification method was developed using laser capture microdissection in combination with direct-captured cell PCR. This procedure was validated with Geobacillus stearothermophilus and further used to identify microbial contaminants present in some industrial milk samples. The microscopically observed contaminants were identified as mainly Methylobacterium species.