Lactate dehydrogenase isozyme patterns from five species of snakes : comparison of rattlesnake vibratory muscle with body epaxial muscle

Lactate dehydrogenase (LDH) isozyme patterns of seven tissues in each of five species of snakes are described from their polyacrylamide gel electrophoretic characteristics. The tissues examined included vibratory tail muscle, non­ vibratory tail muscle, body epaxial muscle, heart muscle, whole blood, liver and kidney. The species of snakes included Crotalus adamanteus, C. h. horridus, Agkistrodon piscivorus and Sistrurus miliarius barbouri from the family Crotalidae and Natrix taxispilota from the family Colubridae. These snakes show a decreasing continuum of tail vibratory activity, respectively, to N. taxispilota, which has a non­vibratory tail muscle. Crotalus adamanteus, C. h. horridus and A. piscivorus have similar LDH isozyme patterns. They represent a case of restricted subunit association and have only four isozymes rather than five which are characteristic of the majority of vertebrates. The missing heteropolymer was determined to be LDH-4 (A3B1) . This is the first time that the four-isozyme system has been reported in Crotalid snakes. Sistrurus m. barbouri and N. taxispilota show non-restricted subunit association and have the five-isozyme LDH pattern. Muscles which contract rhythmically tend to show LDH patterns like those in heart muscle, therefore it was anticipated that rattlesnake vibratory muscle would exhibit a similar pattern. However, this was not the case as vibratory muscle LDH patterns resembled non-rhythmical body epaxial muscle patterns and not those of heart muscle. Vibratory muscle and body epaxial muscle differed in heteropolymer bands LDH-2 (A1B3) and LDH-3 (A2B2), which were wider in vibratory muscle than in body epaxial muscle. There were positive correlations between muscle vibratory activity and increases in heteropolymer band width and intensity. Vibratory muscle LDH patterns were found to be like the white skeletal muscle LDH patterns in most vertebrates and similar to liver LDH isozyrnes. Vibratory muscle and liver have LDH characteristic of anaerobic respiration, however both function in an aerobic environment. Vibratory muscle LDH could represent an alternate energy route during prolonged vibration when oxygen may not be readily available

Transglutaminase 2 in cartilage homoeostasis: novel links with inflammatory osteoarthritis.

Transglutaminase 2 (TG2) is highly expressed during chondrocyte maturation and contributes to the formation of a mineralised scaffold by introducing crosslinks between extracellular matrix (ECM) proteins. In healthy cartilage, TG2 stabilises integrity of ECM and likely influences cartilage stiffness and mechanistic properties. At the same time, the abnormal accumulation of TG2 in the ECM promotes chondrocyte hypertrophy and cartilage calcification, which might be an important aspect of osteoarthritis (OA) initiation. Although excessive joint loading and injuries are one of the main causes leading to OA development, it is now being recognised that the presence of inflammatory mediators accelerates OA progression. Inflammatory signalling is known to stimulate the extracellular TG2 activity in cartilage and promote TG2-catalysed crosslinking of molecules that promote chondrocyte osteoarthritic differentiation. It is, however, unclear whether TG2 activity aims to resolve or aggravate damages within the arthritic joint. Better understanding of the complex signalling pathways linking inflammation with TG2 activities is needed to identify the role of TG2 in OA and to define possible avenues for therapeutic interventions

A comparative study of the chromosomes of rodents

The principal object of this study has been the comparison of the chromosome numbers and morphology of members of a relatively restricted group of mammals, the order Rodentia. While this comparison was being made an attempt was also made to establish the range of chromosome numbers for the group as well as to find out, if possible, the morphological changes of the chromosomes that have occurred during speciation. A discussion of the probable causes of the variation in numbers and morphology has been given, but it is not claimed that the exact nature of these causes has been fully determined. The matter of a base number for the group has been given consideration, and there is added evidence that forty-eight, the probable number assigned by other investigators, is the base number of chromosomes for mammalsEcology, Evolution and Behavio