Simian tumor virus isolate: demonstration of cytopathic effects in vitro

Several cell lines that were derived from primates and inoculated with virus originally obtained from a spontaneous mammary carcinoma showed cytopathic effects characterized by multinucleation. These cytopathic effects appeared as early as 24 holurs after inoculation. Multinucleated cells contained virus particles characteristic of the original virus isolate.     

Psoriatic fibroblasts induce hyperproliferation of normal keratinocytes in a skin equivalent model in vitro

A skin equivalent model has been used to fabricate tissues with psoriatic and normal cells. Psoriatic fibroblasts can induce hyperproliferative activity in normal keratinocytes. The psoriatic epidermis from lesions continues to proliferate at high rates for at least 15 days in this model, and normal fibroblasts are unable to suppress this hyperproliferation. The primary defect in psoriatic skin may reside in the dermal fibroblast.     

Morphological transformation in vitro of human fibroblasts by Epstein-Barr virus: preliminary observations

Human embryo fibroblasts have undergone morphological transformation in vitro after infection by Epstein-Barr virus. The fibroblasts were maintained in suspension during exposure to the virus, and further treatment with inactivated Sendai virus increased the transformation rate. The transformed cells were large and polygonal and grew in discrete, heaped up, foci.     

Oncogenes in radioresistant, noncancerous skin fibroblasts from a cancer-prone family

Li-Fraumeni syndrome is manifested in a variety of neoplasms that are transmitted in a dominantly inherited pattern. The noncancerous skin fibroblasts of family members exhibit a unique characteristic of being resistant to the killing effect of ionizing radiation. A three- to eightfold elevation in expression of c-myc and an apparent activation of c-raf-1 gene have been observed in these noncancerous skin fibroblasts. These results may provide insight into the heritable defect underlying the familial predisposition to a variety of cancers.     

Thyroid hormone action: in vitro demonstration of putative receptors in isolated nuclei and soluble nuclear extracts

Saturable binding activities for triiodothyronine were demonstrated in vitro with isolated nuclei and soluble nuclear extracts of rat liver, kidney, and cultured GH(1) cells. The binding activity can be extracted from nuclei in soluble form with no significant change in hormone affinity and has properties of a nonhistone protein.     

延边奶山羊耳成纤维细胞体外培养的研究

为了给延边奶山羊转基因核移植及乳腺生物反应器研究提供足够且状态良好的细胞,采取延边奶山羊耳部组织块,利用组织块贴壁法进行原代培养和传代培养,对于纯化了的成纤维细胞观察其生长状态,并对4代以后的成纤维进行生长曲线、核型分析,并对细胞进行冷冻复苏试验,检测细胞活力.结果表明,4～13代体外培养成纤维细胞的细胞形态及核型基本正常,13代以后,细胞染色体变异比例增加,15代以后,细胞生长速度减慢;冷冻复苏后的细胞除生长速度减慢外,其它细胞生物学特征均正常,基本符合体细胞克隆、转基因等试验的基本要求,可以用于试验研究.     

Conserved folding in retroviral proteases: crystal structure of a synthetic HIV-1 protease

The rational design of drugs that can inhibit the action of viral proteases depends on obtaining accurate structures of these enzymes. The crystal structure of chemically synthesized HIV-1 protease has been determined at 2.8 angstrom resolution (R factor of 0.184) with the use of a model based on the Rous sarcoma virus protease structure. In this enzymatically active protein, the cysteines were replaced by alpha-amino-n-butyric acid, a nongenetically coded amino acid. This structure, in which all 99 amino acids were located, differs in several important details from that reported previously by others. The interface between the identical subunits forming the active protease dimer is composed of four well-ordered beta strands from both the amino and carboxyl termini and residues 86 to 94 have a helical conformation. The observed arrangement of the dimer interface suggests possible designs for dimerization inhibitors.     

Effectiveness of exogenous DNA transfer to chicken embryo cells in vitro and in vivo using retroviral vectors

The frequency of genetic transformation of target cells in a culture is established to be from 9 × 10^?4 to 3 × 10^?3. A transgenic rooster with integration and expression of the lacZ gene in heart, liver, intestine, and testis cells is produced.     

Host suppression and stability in a parasitoid-host system: experimental demonstration

We elucidate the mechanisms causing stability and severe resource suppression in a consumer-resource system. The consumer, the parasitoid Aphytis, rapidly controlled an experimentally induced outbreak of the resource, California red scale, an agricultural pest, and imposed a low, stable pest equilibrium. The results are well predicted by a mechanistic, independently parameterized model. The key mechanisms are widespread in nature: an invulnerable adult stage in the resource population and rapid consumer development. Stability in this biologically nondiverse agricultural system is a property of the local interaction between these two species, not of spatial processes or of the larger ecological community.     

偏凸山羊草的抗条锈病新基因YrG775的AFLP标记

对小麦抗病种质贵农775与西农97148的F2后代人工接种CY32条锈病菌,对其进行了抗性鉴定,通过卡方检测抗感病单株分离比例,确定贵农775携带有2对重叠抗条锈病基因。从128个AFLP引物组合中,筛选到与其中1个抗病基因YrG775共分离的多态性标记M8P15(1 200 bp),该标记仅能在原始亲本偏凸山羊草中检测到。由于已知来源于偏凸山羊草的Yr17苗期不抗CY32条锈病菌,所以根据抗性鉴定和分子生物学试验结果,推断YrG775很可能是1个来自偏凸山羊草,并与已知抗条锈病基因都不同的新基因。     

Insulin release by emiocytosis: demonstration with freeze-etching technique

The technique of freeze-etching for electron microscopy applied to isolated islets of Langerhans has permitted a successful evaluation of emiocytotic events on the cell surface. The frequency of these events in stimulated cells suggests that emiocytosis represents a significant mechanism for insulin release.     

The fajada butte solar marker: a reevaluation

Evaluation of the Fajada Butte solar marker in Chaco Canyon, New Mexico, on the basis of its ethnographic context and usefulness for confirmatory and anticipatory solar observations indicates that the site does not function as an accurate solar calendar (accurate in the context of the historic Puebloan culture). The site most likely served as a sun shrine rather than as a calendrical observing station. The interpretation of the site as marking the northern declinations of the lunar 18.6-year cycle is not supported by the ethnographic evidence nor can the site be used to anticipate accurately the year of the standstill.     

Increased pyrophosphate in fibroblasts and lymphoblasts from patients with hereditary diffuse articular chondrocalcinosis

The metabolic and genetic factors leading to deposition of calcium pyrophosphate crystals in cartilage of patients with chondrocalcinosis are not well understood. Analysis of cultured fibroblasts and lymphoblasts from 12 affected members of a large kindred showed a mean concentration of intracellular inorganic pyrophosphate two times greater than that in cells from unaffected family members or normal, unrelated volunteers. Increased intracellular pyrophosphate may, therefore, be a biochemical marker for the heterozygous expression of the chondrocalcinosis gene.     

RNA-DNA hybridization: demonstration in a mammalian system of competition by preincubation

Nonspecific intermolecular interactions obscure the interpretation of competition experiments involving hybridization of DNA and RNA in mammalian systems when the labeled RNA/DNA ratio is low. The effect of these interactions can be minimized by choosing a sufficiently high ratio of labeled RNA/DNA. No serious effect of nonspecific interactions is observed in bacteriophage systems, even at very low labeled RNA/DNA ratios.     

Parallels between cytokinesis and retroviral budding: a role for the ESCRT machinery

During cytokinesis, as dividing animal cells pull apart into two daughter cells, the final stage, termed abscission, requires breakage of the midbody, a thin membranous stalk connecting the daughter cells. This membrane fission event topologically resembles the budding of viruses, such as HIV-1, from infected cells. We found that two proteins involved in HIV-1 budding-tumor susceptibility gene 101 (Tsg101), a subunit of the endosomal sorting complex required for transport I (ESCRT-I), and Alix, an ESCRT-associated protein-were recruited to the midbody during cytokinesis by interaction with centrosome protein 55 (Cep55), a centrosome and midbody protein essential for abscission. Tsg101, Alix, and possibly other components of ESCRT-I were required for the completion of cytokinesis. Thus, HIV-1 budding and cytokinesis use a similar subset of cellular components to carry out topologically similar membrane fission events.     

Opiate receptor: demonstration in nervous tissue

Tritiated naloxone, a powerful opiate antagonist, specifically binds to an opiate receptor of mammalian brain and guinea pig intestine. Competition for the opiate receptor by various opiates and their antagonists closely parallels their pharmacological potency. The opiate receptor is confined to nervous tissue.     

Electrotonic coupling between pyramidal cells: a direct demonstration in rat hippocampal slices

Intracellular recordings from pairs of neurons in slices of rat hippocampus directly demonstrated electronic coupling between CA3 pyramidal cells. When two neurons were impaled simultaneously (as verified by subsequent double staining with horseradish peroxidase), current pulses injected into one cell caused voltage changes in other cells. These interactions were bidirectional. Fast prepotentials, historically thought to represent spike activity in dendrites, resulted from action potentials in other electronically coupled pyramidal cells. These data directly demonstrate electrotonic coupling between neurons in the mammalian brain and indicate that some fast prepotentials are coupling potentials. Coupling between pyramidal cells could mediate synchronization of normal rhythmic activity and of burst discharges during seizures.