Histopathology and cell culture characteristics of liver cells from grc − and grc + rats given diethylnitrosamine

The histopathological response and cell culture characteristics of liver cells from the R16 (grc ^–) strain of rats, which carries an MHC-linked deletion, were examined one week after a single intraperitoneal injection of 200 mg/ kg body weight diethylnitrosamine (DEN) and were compared with the response of liver cells from wild type (grc+) rats. The DEN exposure induced hydropicl vacuolar changes in the parenchymal cells and a limited proliferation of oval cells in the periportal areas of the livers of both grc+ and grc rats. Primary culture of collagenase-digested livers consisted of parenchymal, bile ductular and oval-related cells as determined by cell-specific immunohistochemistry. Subpassaged cells from grc+ rats exhibited oval cell ultrastructural morphology, inducible histochemical staining for gammaglutamyl transpeptidase (GGT), and DEN-associated onset of anchorage-independent growth. Primary cultures of liver cells from R16 rats consistently failed to form cell strains upon subpassage.Abbreviations DEN diethylnitrosamine - grc growth and reproduction complex - GGT gamma-glutamyl transpeptidase - MHC major histocompatibility complex     

Breed differences in the distribution of BoLA-A locus antigens in American cattle

A total of 627 cattle representing seven breeds from south central Nebraska, USA were tested for 37 BoLA antigens which behave as products of 37 distinct alleles of the class I BoLA-A locus. Four antigens were absent from all breeds tested. The other antigens showed marked and statistically significant differences in breed distribution. There was no evidence for blank (null) alleles. The number of alleles in each breed ranged from 10 to 20. The Hereford and Simmental populations tested were less polymorphic than the Angus, Brown Swiss, Charolais, Gelbvieh and Limousin populations.     

Serotonin and gastrin/cholecystokinin-like immunorcactive neurons in the larval retrocerebral complex of the blowfly Calliphora erythrocephala

Summary The presence and distribution of neurons immunoreactive against antibodies to serotonin (5-HT) and gastrin/cholecystokinin (gastrin/CCK) has been studied in the larval retrocerebral complex of the blowfly Calliphora erythrocephala, a composite structure which consists of the corpus cardiacum, the corpus allatum, the thoracic gland and a portion of the cephalic aorta. Immunoreactive material was found in all these elements except in the corpus allatum. Six to eight cell bodies in the corpus cardiacum and four to eight cell bodies in the thoracic gland were 5-HT immunoreactive (5-HTi). These 5-HTi cell bodies send processes to the neuropil of the corpus cardiacum and to neurohemal sites in the cephalic aorta, corpus cardiacum and ventral part of the thoracic gland. Six to eight cell bodies in the corpus cardiacum and four to six cell bodies in the thoracic gland reacted with antibodies against gastrin/CCK. These cell bodies send processes to the neuropil of the corpus cardiacum and to neurohemal sites in the corpus cardiacum and the cephalic aorta in a pattern resembling that of the 5-HTi fibers. Additional gastrin/CCK-like immunoreactive fibers were shown to come from the central nervous system via the two nervi corporis cardiaci. An electron-microscopical analysis was performed to analyze further the morphological features revealed by the light-microscopic immunocytochemical technique. This confirmed the existence of neurosecretory-like terminals among the gland cells of the thoracic glands and the existence of neurohemal sites in several regions of the larval retrocerebral complex. Some functional aspects of the retrocerebral complex are discussed on the basis of the presented data.     

The use of poly(L-proline)-Sepharose in the isolation of profilin and profilactin complexes

In the purification of proline hydroxylase by affinity chromatography on poly(L-proline)-Sepharose it was found earlier that two other components, profilin and the complex profilin-actin, also bind with high affinity to this matrix. We have exploited this observation to develop a rapid procedure for the isolation of profilin and profilin-actin complexes in high yields directly from high-speed supernatants of crude tissue-extracts. Through an extensive search for elution conditions, avoiding poly(L-proline) as the desorbant, we have found that active proteins can be recovered from the affinity column with a buffer containing 30% dimethyl sulphoxide. Subsequent chromatography on hydroxylapatite separates free profilin and the two isoforms of profilactin, profilin-actin_β and profilin-actin_γ. The profilin-actin complexes produced this way have high specific activities in the DNAase-inhibition assay, give rise to filaments on addition of Mg²⁺, and can be crystallized. From the isolated profilin-actin complexes the β- and γ-actin isoforms of non-muscle cells can easily be prepared in a polymerization competent form. Pure profilin is either obtained from an excess pool present in some extracts or by dissociation of profilin-actin complexes and removal of the actin.     

Amino acid identities in the three redox center-carrying polypeptides of cytochromebc 1/b 6 f complexes

The comparison of primary structures is extended to 22 cytochromesb orb ₆, 12 cytochromesc ₁ orf, and 8 Rieske FeS proteins. Conclusions are drawn as to their phylogenetic relationship as well as on conserved, functionally important amino acids and secondary structures. The results are in favor of two independent quinone binding sites at opposite surfaces of the membrane, topping one of the two hemes of cytochromeb each.     

Pyruvate Dehydrogenase Activity in Osmotically Shocked Rat Brain Mitochondria: Stimulation by Oxaloacetate

Pyruvate dehydrogenase complex activity (PDHC) measured by CO2 release isotopic assay has generally been much lower than activity measured by the spectrophotometric arylamine acetyltransferase assay (ArAT). Decarboxylation of [1-14C]pyruvate was measured in osmotically shocked rat brain cortical mitochondria. Activity is dependent on the concentration of the substrate pyruvate. Activity of 74.6 units +/- 12.3 SD (n = 22) was observed at 4 mM pyruvate (1 unit = 1 nmol pyruvate decarboxylated/min/mg protein). Activity was dependent on added NAD, CoA, and thiamine pyrophosphate, implying increased mitochondrial permeability after osmotic shock. Freeze/thaw with sonication of the mitochondrial preparation reduced PDHC activity to 11.5 units +/- 3.0 SD (n = 4). Oxaloacetate produced a marked stimulation of activity. The optimal assay contained 3 mM oxaloacetate, and without oxaloacetate activity fell to 15.4 units +/- 9.9 SD (n = 8). These studies highlight the importance of optimal substrate concentrations in the CO2 release isotopic PDHC method. Higher PDHC activity is found with intact mitochondria and thus activity values should be interpreted in the light of the presence or absence of intact mitochondria in individual preparations.     

白腹锦鸡,红腹锦鸡,中国雉鸡SC组型的比较研究

以微铺展—硝酸银染色技术制备三种鸡的SC标本,进行电镜观察。结果表明:三种鸡的SC组非常相似,即2n=82,ZZ/ZW型性别决定,雄性为ZZ。除1号SC和Z-SC为中着丝粒外,其余均为端着丝粒。Z-SC的相对长度有明显的细胞间差异;平均相对长度度介于第3和第4号SC之间。三者SC组型上的差异主要表现在相应SC长度上的不同。并对其亲缘关系及在鸟类进化中的可能地位进行了讨论。此外,在微铺展法制备的锦鸡精母细胞SC标本中还发现了巨大中心粒,这在高等动物尚属首次。     

Persistent measles virus infection enhances major histocompatibility complex class I expression and immunogenicity of murine neuroblastoma cells

The effect of persistent measles virus infection on the expression of major histocompatibility complex (MHC) class I antigens was studied. Mouse neuroblastoma cells C1300, clone NS20Y, were persistently infected with the Edmonston strain of measles virus. The persistently infected cell line, NS20Y/MS, expressed augmented levels of both H-2K^k and H-2D^d MHC class I glycoproteins. Activation of two interferon(IFN)-induced enzymes, known to be part of the IFN system: (2–5)oligoadenylate synthetase and double-stranded-RNA-activated protein kinase, was detected. Measles-virus-infected cells elicited cytotoxic T lymphocytes that recognized and lysed virus-infected and uninfected neuroblastoma cells in an H-2-restricted fashion. Furthermore, immunization of mice with persistently infected cells conferred resistance to tumor growth after challenge with the highly malignant NS20Y cells. The rationale for using measles virus for immunotherapy is that most patients develop lifelong immunity after recovery or vaccination from this infection. Patients developing cancer are likely to have memory cells. A secondary response induced by measles-virus-infected cells may therefore induce an efficient immune response against non-infected tumour cells.     

Effects of lesion of the inferior olivary complex by 3-acetylpyridine on learning and memory in the rat

Summary DA/HAN-strained male rats (pigmented rats) were submitted to two experimental tasks consisting of spatial learning (water-escape) and a passive avoidance conditioning. Both these tasks were performed by different animals. In order to destroy the inferior olivary complex, the animals were injected with 3-acetylpyridine either 9 days prior to the initial learning session or 24 h after completion of the learning task. They were retested (retrieval test) 10 days after the initial learning was achieved. Learning and retention were compared to those noted in control rats. Administration of 3-acetylpyridine before the initial learning did not prevent the spatial learning but the scores were greatly altered and the number of trials needed to reach the fixed learning criterion was much greater than in controls. However, 10 days later the animals had memorized their initial experience. Injection of 3-acetylpyridine after the initial learning session impaired memory: the animals had completely forgotten their initial learning. It can therefore be concluded that lesion of the afferent climbing fibres to the cerebellar cortex alters learning and retention of a spatial task. Such a lesion does not interfere with learning and retention of a passive avoidance conditioning, since in this condition the experimental animals injected with 3-acetylpyridine either before or after the initial learning behave similarly to controls. The effects of the inferior olivary complex lesion are obviously different according to the task to be learnt, suggesting that these two tasks do not require the integrity of the same nervous structures.Abbreviations 3-AP 3-acetylpyridine - C control - ILR initial learning-lesion-retrieval - IOC inferior olivary complex - LIR lesion-initial learning-retrieval