Immunological detection of m- and µ-calpains in the skeletal muscle of Marchigiana cattle.

Calpains are Ca(2+)-dependent proteases able to cleave a large number of proteins involved in many biological functions. Particularly, in skeletal muscle they are involved in meat tenderizing during post mortem storage. In this report we analyzed the presence and expression of µ- and m-calpains in two skeletal muscles of the Marchigiana cattle soon after slaughter, using immunocytochemical and immunohistochemical techniques, Western blotting analysis and Casein Zymography. Therefore, the presence and the activity of these proteases was investigated until 15th day post-mortem during normal process of meat tenderizing. The results showed m- and µ-calpain immunosignals in the cytoplasm both along the Z disk/I band regions and in the form of intracellular stores. Moreover, the expression level of µ-calpain but not m-calpain decreased after 10 days of storage. Such a decrease in µ-calpain was accompanied by a gradual reduction of activity. On the contrary, m-calpain activity persisted up to 15 days of post-mortem storage. Such data indicate that expression and activity of both µ-calpain and m-calpain analyzed in the Marchigiana cattle persist longer than reported in literature for other bovines and may be related to both the type of muscle and breed examined.

Modulation of macrophage activity by aflatoxins B1 and B2 and their metabolites aflatoxins M1 and M2.

Aflatoxins are natural contaminants frequently found both in food and feed. Many of them exert immunomodulatory properties in mammals; therefore, the aim of the current study was to investigate immune-effects of AFB1, AFB2, AFM1 and AFM2, alone and differently combined, in J774A.1 murine macrophages. MTT assay showed that AFB1, alone and combined with AFB2, possess antiproliferative activity only at the highest concentration; such effect was not shown by their hydroxylated metabolites, AFM1 and AFM2, respectively. However, the immunotoxic effects of the aflatoxins evaluated in the current study may be due to the inhibition of production of active oxygen metabolites such as NO. Cytofluorimetric assay in macrophages exposed to aflatoxins (10-100 µM) revealed that their cytoxicity is not related to apoptotic pathways. Nevertheless, a significant increase of the S phase cell population accompanied by a decrease in G0/G1 phase cell population was observed after AFB1 treatment. In conclusion, the results of the current study suggest that aflatoxins could compromise the macrophages functions; in particular, co-exposure to AFB1, AFB2, AFM1 and AFM2 may exert interactions which can significantly affect immunoreactivity.

Histochemical and morphometrical characterization and distribution of fibre types in four muscles of ostrich (Struthio camelus).

A staining procedure used for simultaneously determining three different fibre types in single sections bovine, porcine or ovine skeletal muscle was modified for use with ostrich skeletal muscle. The muscle fibres of gastrocnemius pars externa, tibialis cranialis caput tibiale, tibialis cranialis caput femorale and fibularis longus tendo caudalis were studied. The histochemical results revealed the presence of three types of fibre only in the gastrocnemius pars externa muscle: fast-twitch glycolytic fibres (FG), fast-twitch oxidative glycolytic fibres (FOG) and slow-twitch oxidative fibres (SO), while in the other muscles the FG fibres were absent. The percentage distribution of fibres types showed a higher incidence of SO fibres compared to FOG fibres in tibialis cranialis caput femorale and tibialis cranialis caput tibiale muscles, while it was opposite in the case of the fibularis longus tendo caudalis muscle. In the gastrocnemius pars externa muscle the FG fibres outnumber the other fibres, followed by the SO and FOG fibres. The results of the analysis of variance show significant interaction between muscle x fibre type for every morphometric parameter evaluated. Differences about value of fibres area exists between tibialis cranialis caput femorale and fibularis longus tendo caudalis muscles. Both fibre types in tibialis cranialis caput tibiale muscle have mean values of transversal section area smaller than tibialis cranialis caput femorale. The other morphometric parameters show a similar trend. The gastrocnemius pars externa muscle presents similar dimensions of muscle fibres for the FG and FOG types, and significantly smaller for the SO type.

Histomorphometrical and comparative analysis of three muscles of buffalo (Bubalus bubalis L.).

Three muscles were analyzed, Longissimus dorsi, Semimembranosus and Caput longum Tricipitis brachii taken from nine cow buffaloes, by examining the histochemical and morphometrical characteristics of different muscle fibres types and their distribution inside the examined muscles. Cross sectional area, perimeter, maximum and minimum diameter of about 200 fibres were measured for each muscle, and fast-twitch glycolytic fibres (FG), fast-twitch oxidative-glycolytic fibres (FOG), slow-twitch oxidative fibres (SO) were histochemically differentiated. The data have been elaborated with the SPSS software. The variance analysis indicates that there are not significant differences about dimensions between FG and FOG fibres, while the average values of transversal section area and perimeter are greater than the oxidative fibres in all examined muscles. The Semimembranosus muscle in comparison to the Longissimus dorsi and to the Caput longum Tricipitis brachii muscles has muscle fibres with the smallest value of transversal section area and perimeter. The balanced distribution and intense myofibrillar adenosine triphosphatose and succinic dehydrogenase activities of the three fibres types in Caput longum Tricipitis brachii muscle can be justified by the function performed by this muscle which, together with the other heads of the Triceps brachii acts essentially as extensor of the forearm in fact, differences in the dimensions of the different fibre types inside the three examined muscles have been underlined; this fact can be justified for every muscle performs different motor functions.