Hypertrophic cardiomyopathy in young Maine Coon cats caused by the p.A31P cMyBP-C mutation - the clinical significance of having the mutation

Background

In Maine Coon (MC) cats the c.91G > C mutation in the gene MYBPC3, coding for cardiac myosin binding protein C (cMyBP-C), is associated with feline hypertrophic cardiomyopathy (fHCM). The mutation causes a substitution of an alanine for a proline at residue 31 (p.A31P) of cMyBP-C. The pattern of inheritance has been considered autosomal dominant based on a single pedigree. However, larger studies are needed to establish the significance of cats being heterozygous or homozygous for the mutation with respect to echocardiographic indices and the probability of developing fHCM. The objective of the present study was to establish the clinical significance of being homozygous or heterozygous for the p.A31P cMyBP-C mutation in young to middle-aged cats.

Methods

The cohort consisted of 332 MC cats, 282 cats < 4 years (85%). All cats were examined by 2-D and M-mode echocardiography. DNA was extracted from blood samples or buccal swabs and screened for the p.A31P cMyBP-C mutation in exon 3 of the gene, using polymerase chain reaction followed by DNA sequencing.

Results

The fHCM prevalence was 6.3% in the cohort. Eighteen cats were homozygous and 89 cats were heterozygous for the mutation. The odds ratio for having fHCM for homozygous cats was 21.6 (95% confidence interval 7.01-66.2) - when the group of equivocal cats was categorized as non-affected. Overall, 50% of the cats that were homozygous for the mutation had fHCM. p.A31P heterozygosity was not associated with a significant odds ratio for fHCM. In cats in the 4 to 6 years of age range a similar, non significant, odds ratio was seen in heterozygous cats. Only two cats over four years were homozygous and both were diagnosed with fHCM.

Conclusion

As there is no significant odds ratio associated with being heterozygous for the pA31P cMyBP-C mutation at this age, the mutation must have a very low penetrance in this group. From our data it would appear that most MC cats that develop fHCM due to the p.A31P mutation prior to the age of approximately 6 years do so because they are homozygous for this mutation.     

Frost resistance mechanisms in quinoa (Chenopodium quinoa Willd.)

Quinoa (Chenopodium quinoa Willd.) is traditionally grown in the mountain regions of the Andes where frost is common. However, the physiological mechanisms responsible for the frost resistance observed in quinoa are largely unknown. For this reason, a study on cultivars of quinoa originating from the Andean highlands and from the inter-Andean valleys was performed. Frost tolerance was determined by measuring the average lethal temperature of 50% of the leaf tissues (LT₅₀) by ion leakage, and supercooling activity was assessed by thermal analysis using thermocouples. Quinoa demonstrated supercooling capacity (a mechanism that prevents immediate damage by freezing temperatures) of 5 °C. Ice nucleation temperature was always lower than the LT₅₀. This indicates that the main survival mechanism of quinoa to frost is avoidance of ice formation by moderate supercooling. The study revealed that quinoa has a high soluble sugar content, which may cause a lowering of the freezing point and therefore contributing to lower the LT₅₀. It is suggested that the content of proline and soluble sugars, such as sucrose, may serve as indicators of frost tolerance in quinoa breeding material.     

Adenosine 3'5'-monophosphate phosphodiesterase: multiple molecular forms

By starch-gel electrophoresis and a specific staining technique, seven different molecular forms of cyclic nucleotide phosphodiesterase have been demonstrated in supernatants from homogenates of rat and rabbit tissues. No tissue contains more than four components, but there are distinct differences in component patterns among the various tissues. Tentative molecular weights of the three most prevalent components of rat tissues have been estimated at 135,000, 150,000, and 167,000 by sucrose density gradient centrifugation.     

Effects of swim‐with‐dolphin tourism on the behaviour of spinner dolphins,at Samadai Reef in the Egyptian Red Sea

1. Spinner dolphins, Stenella longirostris, are the primary target for marine mammal tourism in Egypt. The present study investigated the short‐term effects of tourist presence on the behaviour of spinner dolphins at Sha'ab Samadai (Samadai Reef), in the southern Egyptian Red Sea.
2. The reef has a large central lagoon where a population of spinner dolphin regularly rest from mid‐morning to mid‐afternoon; visitors are permitted to snorkel in the southern part of the lagoon, but not in the northern closed zone that the dolphins mainly use.
3. Dolphin behaviour was monitored both on days when tourist boats were present and on days when they were absent. In the presence of tourists the proportion of time that the dolphins spent resting was reduced by two‐thirds, whereas the times spent milling, travelling, and showing avoidance behaviour all increased.
4. Furthermore, upon using Markov chain modelling to investigate the effect of tourist presence on the transition probabilities between dolphin activity states, significant changes were found in 10 of the 25 possible behavioural transitions, including increased probabilities of transitioning from resting to milling or travelling, from milling to travelling or avoiding, and from travelling to avoiding.
5. These findings raise concerns that despite the management measures in place, tourist activities affect the dolphins’ behaviour to a greater extent than was previously apparent, with potential long‐term negative effects on their energy budget. The study led to proposals for amending the zoning of the site and for strengthening the regulations for tourist vessels.

     

Effect of astaxanthin and vitamin A on growth and survival during first feeding of Atlantic salmon, Salmo salar L.

Abstract. The interactions of astaxanthin and vitamin A on the growth and survival of Atlantic salmon, Salmo salar L., during the first-feeding period were examined using semi-purified diets. Alevins, with a mean initial weight of 0.18g, were fed diets supplemented with 0, 20 and 40 mg astaxanthin/kg dry diet and 0, 750 and 1500 μg vitamin A/kg dry diet for 20 weeks. The weights of the fish were recorded throughout the experimental period and carcasses were collected for proximate composition, vitamin A and astaxanthin analyses at the beginning and end of the experiment. The feeds were analysed for proximate composition, vitamin A and astaxanthin levels.
No interaction between astaxanthin and vitamin A was found in relation to the growth, survival or vitamin A content of the fry. Astaxanthin was found to strongly influence the growth, survival and vitamin A concentration in the fish. Poor growth and low survival rates were observed in groups fed diets without astaxanthin, including the group fed a diet with sufficient vitamin A. The results indicate both a provitamin A function of astaxanthin and a specific function of astaxanthin. Astaxanthin was found to be essential to alevins during the first-feeding period.     

Blackspot bruise susceptibility of potato tubers during growth and storage determined by two different test methods

Summary Blackspot bruise susceptibility of potato tubers of the cultivar Oleva increased during growth but was stable during storage independent of the type of impact method employed. With the pendulum test method, blackspots were observed in the tubers of the cultivar Dali during the final growth period and early in the storage period, whereas no blackspots were observed when they were treated on a shaking table. The relationships between blackspot susceptibility and dry matter content, size of starch granules, concentration of N, K, Mg and Ca, membrane leakiness and turgor pressure in the tuber cortices fluctuated according to cultivar, developmental stage of the tuber and the test method employed. The study underlines the importance of choosing a test method, which closely simulates the impact conditions of commercial situations, since the relationships between blackspot susceptibility and various physiological parameters of the tuber were found to change according to the impact condition employed.     

Growth Hormone Receptors in the Porcine Testis During Prepuberty

Supplementation of exogenous growth hormone (GH) during prepuberty advances onset of spermatogenesis in boars, but the mechanism of action is unknown. The present study is an investigation of the presence and characteristics of testicular growth hormone receptors (GHR). A total of 36 boars were castrated, three boars every 10 days, between the ages of 10 and 120 days. Testicular membrane preparations of 10, 20, 30, 50, 70, 100 and 120‐day‐old boars were used to determine ¹²⁵I‐bGH binding and Scatchard analysis. Liver from a 60‐kg barrow was used for comparison. Specific ¹²⁵I‐bGH binding to testicular membrane preparations occurred in all age groups with the exception of 20‐day‐old boars at levels of 30–40% of liver binding. At 30 days of age the unlabelled bGH at 1.1 ng/tube achieved half maximal inhibition (ID₅₀). Results of Scatchard analysis indicated a single class of binding sites. Binding affinity was 2.89 × 10⁹m with a binding capacity of 12 fmole/mg membrane protein. The results from this study suggest that GH may act directly on the cells of the prepubertal boar testis.