Photosynthetic acclimation of shade-grown red pine (Pinus resinosa Ait.) seedlings to a high light environment

Photosynthetic light acclimation in red pine (Pinus resinosa Ait.) seedlings was examined in a greenhouse study to better understand the physiological response of this species to increased light intensity following release from competition. Seedlings grown in a high (HL), medium (ML) or low (LL) light environment for 12 weeks were transferred to high light. Gas exchange and chlorophyll fluorescence of ML and LL seedlings were measured prior to and following transfer and compared with the HL control treatment. Photosynthetic characteristics were related to initial light treatment and time after transfer. Acclimation of gas exchange features to high light in shade formed ML and LL foliage was relatively rapid, with similar values among light treatments within 57 days of transfer. Acclimation of net photosynthetic rate was similar in ML and LL seedlings, and was associated primarily with increased mesophyll conductance to CO₂. The ratio of variable to maximal chlorophyll fluorescence (F_v/F_m) decreased initially after transfer, especially in LL seedlings, but recovered to normal values after 57 days. Red pine seedlings appear to be well adapted for photosynthetic acclimation to high light intensity, consistent with that reported for other early successional tree species.     

Comparison of the ability of feline calicivirus (FCV) vaccines to neutralise a panel of current UK FCV isolates

Feline calicivirus (FCV) comprises a large number of strains which are related antigenically to varying degrees. The antigenic variability creates problems for choosing antigens to include in vaccines. Historically, these have been selected for use based on their cross-reactivity with a high proportion of field strains. However, it is important to determine the current level of cross-reactivity of vaccines and whether or not this may be decreasing owing to widespread vaccine use. In this in vitro study, we have compared the ability of antisera to two vaccine viruses (FCV strain F9 and FCV strain 255) to neutralise a panel of 40 recent UK field isolates. These 40 isolates were obtained by randomised, cross-sectional sampling of veterinary practices in different geographical regions of the UK so as to ensure they were representative of viruses circulating in the veterinary-visiting population of cats in the UK. Virus neutralisation assays showed that both vaccine strains are still broadly cross-reactive, with F9 antiserum neutralising 87.5% and 255 antiserum 75% of isolates tested with antiserum dilutions of 1 in 2 or greater. However, when antibody units were used, in order to take account of differences in homologous titres between antisera, fewer isolates were neutralised, with F9 antiserum showing a slightly higher proportion of isolates neutralised than 255. Multivariable analysis of the sample population of 1206 cats from which the 40 isolates were derived found that vaccinated cats were at a decreased risk of being positive for FCV, whereas cats from households with more than one cat, and cats with mouth ulcers were at increased risk. In addition as cats became older their risk of shedding FCV decreased.     

Leading the pack: Best practices in comparative canine cancer genomics to inform human oncology

Pet dogs develop spontaneous cancers at a rate estimated to be five times higher than that of humans, providing a unique opportunity to study disease biology and evaluate novel therapeutic strategies in a model system that possesses an intact immune system and mirrors key aspects of human cancer biology. Despite decades of interest, effective utilization of pet dog cancers has been hindered by a limited repertoire of necessary cellular and molecular reagents for both in vitro and in vivo studies, as well as a dearth of information regarding the genomic landscape of these cancers. Recently, many of these critical gaps have been addressed through the generation of a highly annotated canine reference genome, the creation of several tools necessary for multi-omic analysis of canine tumours, and the development of a centralized repository for key genomic and associated clinical information from canine cancer patients, the Integrated Canine Data Commons. Together, these advances have catalysed multidisciplinary efforts designed to integrate the study of pet dog cancers more effectively into the translational continuum, with the ultimate goal of improving human outcomes. The current review summarizes this recent progress and provides a guide to resources and tools available for comparative study of pet dog cancers.     

Morphological characteristics associated with tolerance to competition from herbaceous vegetation for seedlings of jack pine,black spruce,and white pine

Tolerance of bareroot and container-grown seedlings of black spruce (Picea mariana (Mill.) B.S.P.), jack pine (Pinus banksiana Lamb.), and eastern white pine (Pinus strobus L.) to competition from herbaceous vegetation was examined in the first five years after planting on a site in the Great Lakes/St. Lawrence forest of Ontario, Canada. Shoot and root morphological characteristics of various stocktypes were measured before planting and correlated with 5-year survival and growth following control and no control of herbaceous vegetation. For black spruce and jack pine, medium-sized bareroot stocktypes had greater relative 5-year stem volume growth in the presence of herbaceous vegetation than did container stock of either species or large bareroot stock of spruce. Relative volume growth was measured as the ratio of the cumulative stem volume increment in the presence of vegetation (Veg) to that in the absence of vegetation (NoVeg), i.e., the Veg:NoVeg ratio. In white pine, the Veg:NoVeg ratio of volume increment of medium container and large bareroot stocktypes exceeded that of small container and medium bareroot stocktypes. In jack pine, root collar diameter at planting and number of first-order lateral roots were positively correlated with 5-year Veg:NoVeg ratio of volume increment. In white pine, the Veg:NoVeg ratio was also positively correlated with root collar diameter at planting and with root volume. In black spruce, the ratio was not related to pre-plant morphology. Thus, for white pine and jack pine, certain pre-plant morphological features may be useful in forecasting the relative ability of different stocktypes to grow under herbaceous competition conditions in the field.     

A survey of health care and disease in geriatric horses aged 30 years or older

This study reports on aspects of preventive health care and on the prevalence of disease in geriatric (≥30 years old) horses and ponies in North-West England and North Wales. Of 128 questionnaires mailed to horse owners, 87 useable responses were received and 69 horses were subject to veterinary examination. Of the animals examined, 16% were underweight with body condition scores (BCS)<2/5, and 10% were overweight (BCS>3/5). This contrasted with the owner responses that reported 23% of the animals surveyed to be underweight and only 3% to be overweight. When assessed at trot, 77% of the horses were lame on at least one limb, with 97% having a reduced range of motion in at least one joint. Only 16% of these animals were reported by owners to have been lame within the previous 12 months. Owner-reported changes to hair coat were significantly associated with hirsutism or abnormal moulting detected at clinical examination (39%). At least one ophthalmic lesion was identified in all of the horses and ponies examined and 17% of owners reported that their animal had experienced visual problems within the previous year. Although dental abnormalities were detected in all animals where an oral examination was performed, only 42% of owners reported that their horse suffered from a known dental disorder. In general, despite a high prevalence of disease detected in these geriatric animals and with the majority having multiple abnormalities at clinical examination, there was under-reporting/under-recognition of these health problems by owners.     

Comparison of two thiopental infusion rates for the induction of anaesthesia in dogs

OBJECTIVE: To compare the induction dose requirements of thiopental using two different infusion rates for induction of anaesthesia in dogs. STUDY DESIGN: Prospective, randomized study. ANIMALS: Fifty, healthy (ASA I or II) client-owned dogs with a mean age of 4.1 years and a mean mass of 20.4 kg undergoing elective surgery. MATERIALS AND METHODS: Animals were randomly assigned to receive an infusion of 2.5% thiopental at a rate of either 0.1 ml kg(-1) minute(-1) or 0.4 ml kg(-1)minute(-1), 30-40 minutes after pre-anaesthetic medication with intramuscular acepromazine (0.025 mg kg(-1)) and pethidine (3.5 mg kg(-1)). Thiopental administration was controlled by a precision syringe driver. Statistical analyses of the results, using the outcome 'mg kg(-1) required for induction' (log-transformed) included unpaired t-tests for all categorical data (thiopental infusion rate, breed, sex, obesity, sedation quality) and univariable linear regression for continuous variables (mass, age). All variables were then considered in a multivariable linear regression model. The quality of induction with the two different infusion rates was also assessed. RESULTS: After controlling for quality of sedation, the thiopental induction dose requirement was significantly less (p < 0.001) with the slower infusion rate (median = 7.5 mg kg(-1); range 4.9-13.7) compared with the faster infusion rate (median =11.0 mg kg(-1); range 6.6-18.0). The quality of sedation also affected the dose required (p = 0.03). The slower infusion rate was associated with a significantly poorer induction quality (p = 0.03) [corrected] CONCLUSIONS: Slow thiopental infusion (0.1 ml kg(-1) minute(-1)) for anaesthesia induction after acepromazine/pethidine pre-anaesthetic medication reduced the induction dose requirement, although the quality of induction was inferior. CLINICAL RELEVANCE: The induction dose of thiopental was reduced with a slower administration rate and so slow administration is recommended in thiopental-sensitive animals.     

Impaired thermosensation in mice lacking TRPV3, a heat and camphor sensor in the skin

Environmental temperature is thought to be directly sensed by neurons through their projections in the skin. A subset of the mammalian transient receptor potential (TRP) family of ion channels has been implicated in this process. These "thermoTRPs" are activated at distinct temperature thresholds and are typically expressed in sensory neurons. TRPV3 is activated by heat (>33 degrees C) and, unlike most thermoTRPs, is expressed in mouse keratinocytes. We found that TRPV3 null mice have strong deficits in responses to innocuous and noxious heat but not in other sensory modalities; hence, TRPV3 has a specific role in thermosensation. The natural compound camphor, which modulates sensations of warmth in humans, proved to be a specific activator of TRPV3. Camphor activated cultured primary keratinocytes but not sensory neurons, and this activity was abolished in TRPV3 null mice. Therefore, heat-activated receptors in keratinocytes are important for mammalian thermosensation.