Intermuscular variation in tenderness: association with the ubiquitous and muscle-specific calpains

The biochemistry of intermuscular variation in tenderness is not fully understood. To investigate the role of the calpains in this process we performed two experiments using bovine and ovine species. In the bovine experiment, two distinct muscles, longissimus thoracis et lumborum (LT) and psoas major (PM), were used. In the ovine experiment, four muscles, LT, PM, semimembranosus (SM), and semitendinosus (ST), were used. Muscles were sampled at death for the determination of the steady-state mRNA level of calpains and calpastatin and the activities of calpain 1, 2, and calpastatin. Muscles were also sampled to determine the temporal changes in pH, tenderness, and the activity of the ubiquitous calpain system during postmortem aging. The results of the relative rate of tenderization in both species was found to be related to muscle type; LT had the highest value in both species. Within species, the mRNA steady-state levels of calpain 1 and calpastatin were similar in various bovine and ovine muscles. Bovine calpain 2 mRNA level was significantly lower in the LT than in the PM. Ovine calpain 2 mRNA level was lower, but not significantly different, in the LT compared to the other muscles. The mRNA level of bovine calpain 3 was significantly higher in the LT muscle than in the PM. In the ovine, the mRNA level of calpain 3 was highest in the LT, followed by SM, PM, and ST. Results on the activity of the ubiquitous calpain system in various muscles at death were dependent on muscle type and species. Temporal changes in the activity of calpains and calpastatin during the first 24 h of postmortem aging were similar in the muscles studied: calpain 1 and calpastatin declined significantly and calpain 2 remained relatively unchanged. The temporal changes in muscle pH in both experiments indicated that the extent and rate of pH decline during aging was related to muscle type. Correlation analysis between the relative rate of tenderization and mRNA expression of calpains revealed a strong relationship with calpain 3 in both species.     

Segregation ratios and growth rate in inactive ovine metallothionein 1a-ovine growth hormone transgenic mice

Objectives were to determine whether the oMt1a-oGH transgene shows normal Mendelian segregation and whether oMt1a-oGH mice exhibit normal growth without the zinc supplementation required to increase plasma oGH levels and stimulate growth. Transgenic mice were reciprocally backcrossed for four generations to high growth and control lines to form lines GM and GR, respectively. In the fifth generation, hemizygous transgenic mice (T/-) were crossed within each line. Pooled across backcross generations, there was a deficit (P < 0.001) of T/- progeny in lines GM (31.6%) and GR (22.2%) compared with expected (50%). In the T/- x T/- cross, the combined percentage of homozygous (T/T) and hemizygous transgenic mice was less (P < 0.001) than expected (75%) in both GM (44.2%) and GR (38.5%). Backcross T/- mice had lower (P < 0.05) 3-wk BW and lower (P < 0.001) 6-wk BW and 3- to 6-wk postweaning gains than nontransgenic mice. Similar genotypic differences were found in the T/- x T/- cross. No significant growth differences were found between T/T and T/- progeny. Using segregation ratios from the T/- x T/- mating, the relative fitness estimates of T/T, T/-, and -/- (nontransgenic) mice were 0.345, 0.223, and 1.0, respectively, in line GM and 0.218, 0.205, and 1.0 in line GR. Fitness estimates in the back-cross for T/- and -/- were 0.463 and 1.0 in line GM and 0.285 and 1.0 in line GR. Abnormal segregation ratios may be due to germline mosaicism or reduced fitness due to differential embryo survival. Reduced growth of oMt1a-oGH transgenic mice when the transgene is switched off suggests a subtle developmental abnormality, which may contribute to a reduction in fitness.     

Severe complication after administration of formalin for treatment of progressive ethmoidal hematoma in a horse

Formalin was injected into an ethmoidal hematoma in an 18-year-old Arabian gelding. Abnormal neurologic signs were observed within minutes of the injection. The horse did not respond favorably to medical treatment of the neurologic signs and was euthanatized. Postmortem examination revealed erosion and necrosis of the ventral cribriform plate, which appeared to have allowed the injected formalin to reach the rostral portion of the frontal lobe of the brain. Endoscopy and radiography had been performed prior to euthanasia, but neither delineated the cribriform lesion. Before treating large progressive ethmoidal hematomas with formalin, it may be beneficial to perform computed tomography to assess the extent of damage caused by the lesion.     

Relationship between skeletal muscle-specific calpain and tenderness of conditioned porcine longissimus muscle

Tenderization of skeletal muscle in meat animals has been closely linked to the postmortem activity of the calpain proteolytic enzyme system, which includes the specific inhibitor calpastatin. Increased understanding of the skeletal muscle-specific calpain isoform p94 has prompted suggestions as to whether it too could have a role in the tenderization process. In this study, two groups of pigs were identified in which shear force measurements after 8 d of conditioning indicated a large variation in the tenderness of longissimus muscle. The quantity of p94 in the muscle was monitored by immunoblotting, using a porcine-specific polyclonal antibody raised against a recombinant peptide fragment generated as a fusion protein. The antiserum recognized a 94-kDa protein associated with myofibrils in skeletal but not cardiac muscle, as expected for this calpain isoform, although it could not be tested with the native protein because of the extreme instability of p94. In the first experiment, the mean shear force for the tough group was 6.71 +/- .28 kg (n = 12, SEM) and that of the tender group was 3.87 +/- .12 kg (n = 12), but there was no difference in the normalized absorbance of the immunopositive 94 kDa band on Western blots from samples collected at approximately 40 min postmortem. In the second experiment, the stability of p94 in chilled carcasses was investigated over 24 h, using a further two groups of 10 tough and 10 tender pigs of mean shear force values 5.36 +/- .14 kg and 2.81 +/- .15 kg, respectively. In tough and tender animals, there was a decline (P < .05) in the 94-kDa immunostaining material of mean half-lives of 13.8 and 12.9 h, respectively, although there was considerable variability. Despite this variability in half lives and shear force values, no correlation was seen between these factors. Thus, in porcine longissimus muscle, the variability in tenderness after 8 d of conditioning cannot be attributed to an underlying variability in p94.     

河南省花生锈病侵染来源的初步研究

本世纪七十年代以来,花生锈病在亚洲、非洲和大洋洲的许多地方流行,已成为世界性的病害。我国的广东、广西、福建和台湾省也曾迅速蔓延,造成严重危害。为了澄清此病在我省的发生情况,我们于1981年到八个地区的十七个县作过调查,发现大部分县都有发生。淮河以南地区已相当严重,估计减产在1—3成,已超过叶斑病的危害。我们还镜检各县病株,均未发现有冬孢子存在。为了明确我省花生锈病的侵染来源,以期为防治提供依据,我们自1981年起对此进行了研究,结果如下。     

中国舞毒蛾Lymantria dispar(Linnaeus)天敌考察

前言在1982年以前,有关中国境内舞毒蛾天敌的专门报道较少,在散见的出版书刊中曾提到一种病毒和一些寄生天敌。1982年我们在北京市、黑龙江和吉林省的52个考察地点进行了为期8周的考查。本文主要报道考察中所采集到的有关舞毒蛾的天敌。材料与方法考察地点及详细情况见Schaefer等的文章。在考察的52个地点采集了舞毒蛾的幼虫和所见到的捕食舞毒蛾幼虫的天敌,并将舞毒蛾幼虫进行饲养,直到寄生天敌全部出来为止。舞毒蛾的幼虫饲养在90×15毫米的塑料培养皿,纸盒或塑料袋中,用蒙古栎     

Age-related changes in porcine corticosteroid-binding globulin (pCBG) as determined by an enzyme-linked immunosorbent assay

The objectives of this study were to develop an assay for the direct measure of porcine corticosteroid-binding globulin (pCBG) and to confirm age-related changes in plasma pCBG concentration. Isolation and purification of pCBG from plasma was performed by affinity chromatography and HPLC–DEAE anion exchange techniques. Analysis by SDS–PAGE revealed two polypeptides (54 and 59 kDa) having similar amino acid homology (>50%) to previously reported sequences of seven mammalian species for the first 33 amino acids. Porcine CBG (20 ng/well) was immobilized to microtiter plates and standards or samples added along with rabbit antiserum developed against the purified pCBG. Goat anti-rabbit IgG-alkaline phosphatase conjugate was added followed by p-NPP substrate. The resultant color development was read at 405 nm. Intra- and interassay coefficients of variation (n=26) of a pooled sample were 10 and 15%, respectively. Age-related changes (P<0.001) in plasma pCBG concentration (n=203) from day 3 through 168 of age confirmed that, in the pig, changes seen in the percent distribution of cortisol among protein bound and free forms around day 28 of age are associated with an increase in CBG concentration.     

Optimal fecal assessment

Fecal testing is a common component of most gastrointestinal work-ups. A multitude of diagnostic techniques are available for identifying parasites and pathogens, or showing abnormalities of flora. Optimal fecal assessment involves careful formulation of a differential list based on signalment, history, and clinical signs. Tests should be selected and interpreted based on their relative sensitivity and specificity for specific conditions. It is essential to use effective testing methods for the etiologies of concern. This article reviews the plethora of diagnostic techniques available for fecal assessment. Indications, limitations, and issues of specimen handling for each technique are discussed. The optimal approach to the diagnosis of some common parasites, pathogens, abnormalities of flora, and metabolic conditions are covered.