Photoinhibition, carotenoid composition and the co-regulation of photochemical and non-photochemical quenching in neotropical savanna trees

Plants in the neotropical savannas of central Brazil are exposed to high irradiances, high air temperatures and low relative humidities. These conditions impose a selection pressure on plants for strong stomatal regulation of transpiration to maintain water balance. Diurnal adjustments of non-photochemical energy dissipation in photosystem II (PSII) provide a dynamic mechanism to reduce the risk of photoinhibitory damage during the middle of the day when irradiances and leaf temperatures are high and partial closure of the stomata results in considerable reductions in internal CO(2) concentration. At the end of the dry season, we measured diurnal changes in gas exchange, chlorophyll fluorescence parameters and carotenoid composition in two savanna tree species differing in photosynthetic capacity and in the duration and extent of the midday depression of photosynthesis. Non-photochemical quenching and its quantum yield were tightly correlated with zeaxanthin concentrations on a total chlorophyll basis, indicating that the reversible de-epoxidation of violaxanthin to antheraxanthin and zeaxanthin within the xanthophyll cycle plays a key role in the regulation of thermal energy dissipation. In both cases, a single linear relationship fitted both species. Although efficient regulation of photochemical and non-photochemical quenching and adjustments in the partitioning of electron flow between assimilative and non-assimilative processes were operating, these trees could not fully cope with the rapid increase in irradiance after sunrise, suggesting high vulnerability to photoinhibitory damage in the morning. However, both species were able to recover quickly. The effects of photoinhibitory quenching were largely reversed by midday, and zeaxanthin rapidly converted back to violaxanthin as irradiance decreased in late afternoon, resulting in the maximal quantum yield of PSII of around 0.8 just before sunrise.     

Nutritional planning for Nellore heifers post-weaning to conception at 15 months of age: performance and nutritional,metabolic, and reproductive responses

Tropical Animal Health and Production - The objective of this study was to evaluate the effects of strategic supplementation in the dry period and dry/rainy transition period on the performance and...     

p62/SQSTM1 expression in canine mammary tumours: Evolutionary notes

Recent studies highlighted the role of autophagy as a cardinal regulatory system for homeostasis and cancer‐related signalling pathways. In this context, the deregulated expression of p62 – Sequestosome1 (p62/SQSTM1) – a protein acting both as an autophagy receptor and signalling hub, has been associated with tumour development and chronic inflammation. Multiple clinical studies test drugs targeting autophagy, and even more research is on the way to clinical trials. However, no comparative investigations have been carried out to identify adequate preclinical models to assess p62‐based medicine. In veterinary oncology the role of p62 in cancer‐related pathways has been largely ignored. We compared p62 sequences in multiple organisms and found that canine p62 significantly diverges from the humans and from other animals sequences. Then, we chart by immunohistochemistry the expression levels of p62 in canine mammary tumours. A total of 66 tumours and 10 non‐neoplastic mammary samples were examined. The expression of p62 was higher in normal tissue and adenomas than carcinomas, with lowest levels of p62 protein detected in high grade carcinomas. In all cases examined the tumour stroma appeared to be p62‐negative. Taken together our results would suggest that in dogs the association between p62 expression and cancer cells overturns that reported in human breast carcinoma, where p62 accumulates in malignant cells as compared to normal epithelium. Thus, at least in canine mammary tumours, p62 should be not considered a tumour‐rejection antigen for an anti‐cancer immunotherapy.     

Comparative antifungal effect and mode of action of tetraconazole on Ustilago maydis

Tetraconazole, a new, recently introduced antifungal triazole, has been assayed in parallel with a number of standard analogues on various sensitive strains of Ustilago maydis. The values of EC₅₀ and EC₉₀ tetraconazole concentrations, determined on strain ATCC 14826 in agar, were 0.5 × 10⁻⁶ and 3.5 × 10⁻⁵ , respectively, in reasonable agreement with those needed to inhibit by 50% and 90%, respectively, the ergosterol biosynthesis in broth cultures. Squalene and 12 sterols have been extracted from the latter, characterized and quantified. Accumulation of 14α-methylsterols and reduction of ergosterol and other late precursors are consistent with the inhibition of 14α-demethylase caused by the title compound.     

Characterization and genetic analysis of field isolates ofBotryotinia fuckeliana (Botrytis cinerea) resistant to dichlofluanid

Field isolates ofBotryotinia fuckeliana were collected from naturally infected plants. Their responses to the multisite fungicide dichlofluanid in mycelium growth test fell into three phenotypic classes, characterized by the following EC₅₀ (and MIC) values ing ml^–1: sensitivity, 1–3 (6–10); low resistance, 3–10 (> 100); high resistance, 10–30 (> 100). The corresponding values obtained for these classes in a spore germination test were respectively: 0.05 (0.2), 0.05–0.1 (0.5), 0.5–1 (0.9–1.5). Resistant isolates were crossed with two sensitive and two resistant strains of appropriate mating type to determine the genetic basis of resistance. Distribution of resistance phenotypes in ascospore progeny indicated that a gene, namedDic1, was probably responsible for the low or high resistance of 14 mutants selectively collected from experimental plots of greenhouse-grown gerbera sprayed several times with dichlofluanid or tolyfluanid. A second gene, namedDic2, was probably responsible for the low resistance displayed by two isolates (from grapevine and from carnation) maintained in the laboratory collection. As a result of the investigation, the use of dichlofluanid in integrated management programmes against grey mould is discussed.     

The Importance of Wild Canids in the Epidemiology of Rabies in Northeast Brazil: A Retrospective Study

Rabies is an endemic disease in Brazil, where it is considered a serious public health problem. Although the number of human and dog‐transmitted cases has declined in recent decades, rabies in wildlife has emerged considerably. Among the sylvatic animals, wild canids have been considered important hosts of the rabies virus. We performed a retrospective study of reported cases of rabies in wild canids and human victims in Ceará state (Northeast Brazil) during 2003 to 2013. Information was provided by governmental laboratories involved in rabies detection and by the Ministry of Health. From January 2003 to December 2013, a total of 11 931 animal samples were examined for rabies. Positivity were detected in 438 samples (3.67%), of which 229 (52.28%) were domestic animals, 105 (23.97%) wild canids and 104 (23.74%) other wild animals (bats, marmosets and raccoons). Approximately 33% of wild canids surveyed (n = 317) were positive for rabies. During the studied period, a total of 1923 attacks on humans by wild canids were registered. Males (n = 1405) were more affected than females (n = 520; 72.98% versus 27.01%), and the median age of all cases was 36.5 years. Injuries to individuals up to 19 years old corresponded to approximately 30% (n = 565) of all cases. Most of the victims lived in rural areas (72.46%; n = 1395), and the majority showed bites (81.13%; n = 1677) or scratches (12.23%; n = 253). Injuries were considered profound (52.1%; n = 1003), superficial (40.91; n = 788) or multiple with severe laceration (6.98%; n = 134). Only 1300 (67.53%) victims were enrolled for the complete rabies post‐exposure prophylaxis scheme. Data from the present study confirm that wild canids are important hosts of rabies virus in northeastern Brazil and jeopardize rabies control in this area. Local authorities should focus their efforts in education of health professionals. In addition, strategies should be formulated to preserve wildlife.     

Dose response of rumen‐protected conjugated linoleic acid supplementation to fattening bulls and heifers on growth,and carcass and meat quality

We investigated the influence of rumen‐protected conjugated linoleic acid (rpCLA) on growth performances, and carcass and meat quality traits in beef. Twenty‐four young bulls and 30 heifers obtained from double‐muscled beef sires and dairy cows were fed a low‐protein ration (110 g/kg DM of crude protein) supplemented with 0, 8 or 80 g/d of a commercial rpCLA product. The animals were monthly weighed and scored for body muscularity and fatness. Blood samples were collected after 140 days on feed. Animals were slaughtered when they reached average in vivo fatness scores of around 2.5 (heifers) and 2.0 (bulls) points respectively. At slaughter, carcasses, various organs and parts of the gastrointestinal tract were weighed; the 5th rib was dissected and its tissue and muscle chemical composition was determined. The rpCLA had little influence on growth performance but decreased the blood urea content by 28% (p < 0.01). The rpCLA × sex interactions for daily gain (p < 0.05), conformation scores (p < 0.01), and blood creatinine content (p < 0.05) suggest that males were more responsive to rpCLA than females when fed a low‐protein ration, probably because of the metabolic protein‐sparing effect of CLA. Only slight differences were observed in carcass weight and quality at slaughter. The results indicate that the response of beef cattle to rpCLA is dependent on sex or on their propensity for lean and fat accretion. It is also possible that counteracting feedback mechanisms compensate for the influence of rpCLA administration over the course of growth.     

LPS-induced sickness behavior is not affected by selenium but is switched off by psychogenic stress in rats

Veterinary Research Communications - Sickness behavior (SB) is considered part of the adaptive behavioral and neuroimmune changes that occur in response to inflammatory processes. However, SB is a...     

Early luteal development in Santa Inês ewes superovulated with reduced doses of porcine follicle‐stimulating hormone

The aim was to compare the early luteal development in ewes superovulated with different doses of pFSH. Twenty‐nine Santa Inês ewes received a progesterone device (CIDR®) for 8 days. Gonadotrophic treatment started on Day 6: G200 (control, n = 9, 200 mg); G133 (n = 10, 133 mg); and G100 (n = 10, 100 mg of pFSH). On Day 6, all females received eCG (300 IU). B‐mode and spectral Doppler ultrasonography were performed daily during the early luteal phase (Days 11–15) to monitor the development of corpora lutea (CLs; dimensions) and ovarian arteries indices. CLs were also classified as normal or prematurely regressed (PRCL) on Day 15 by videolaparoscopy. Ewes from G100 and G133 showed gradual increase in luteal diameter during the early luteal phase (p < 0.001), whereas G200 animals presented increase from Day 11 to Day 13, and then decrease on Days 14 and 15 (p < 0.001). The G200 females showed greater percentage of PRCL (45.20%) than those of the other groups (p < 0.001). The normal CLs number was greater in G100 than in G133 (p = 0.04), while the PRCL number was greater in G200 than in the other groups (p = 0.03). Resistive index (RI) was greater in G200 than in G100 (p = 0.02). RI was lower in Day 12 than Day 15 (p = 0.02). Pulsatility index (PI) was greater on Days 14 and 15 (p < 0.01). In conclusion, the lowest dose of pFSH (100 mg) can be considered sufficient for an efficient superovulatory response in sheep, producing better CLs development dynamic in early luteal phase and ovarian blood perfusion and smaller number of PRCL than the traditional (200 mg) pFSH dose.