Comparison of simian immunodeficiency virus isolates

Information on the extent of genetic variability among non-human primate lentiviruses related to human immunodeficiency virus (HIV) is sorely lacking. Here we describe the isolation of two molecular clones from the simian immunodeficiency virus (SIV) and their use to derive restriction endonuclease maps of five SIV isolates from rhesus macaques and one from a cynomolgus macaque. Although similar, all six viral isolates are readily distinguishable; the single isolate from a cynomolgus macaque is the most different. The restriction endonuclease map of one macaque isolate (SIVMAC-251) is identical to that published by others for STLV-IIIAGM of African green monkeys and for HTLV-IV of humans. Nucleotide sequences from the envelope region of cloned SIVMAC-251 have more than 99% identify to previously published sequences for STLV-IIIAGM (refs 2, 4) and HTLV-IV (ref. 4). These results and other observations provide strong evidence that isolates previously referred to as STLV-IIIAGM and HTLV-IV by others are not authentic, but were derived from cell cultures infected with SIVMAC-251.

Molecular genotypes of the human T cell receptor gamma-chain

New RFLP of the human TCR gamma-chain defined by a single restriction enzyme (PvuII) are described. They define three alleles and allow haplotype assignments within families. They occur at a high frequency within the population studied and are useful for studies on disease associations with the gamma-chain genes. The PvuII sites flank the C gamma 2 gene. A polymorphic site maps to an area 0.5 kb downstream of C gamma 2-exon III. The second RFLP appears to be the result of a 3-kb insertion giving rise to differences in the number of copies of exon II in the C gamma 2 gene.

Molecular genotypes of the human T cell receptor gamma-chain

New RFLP of the human TCR gamma-chain defined by a single restriction enzyme (PvuII) are described. They define three alleles and allow haplotype assignments within families. They occur at a high frequency within the population studied and are useful for studies on disease associations with the gamma-chain genes. The PvuII sites flank the C gamma 2 gene. A polymorphic site maps to an area 0.5 kb downstream of C gamma 2-exon III. The second RFLP appears to be the result of a 3-kb insertion giving rise to differences in the number of copies of exon II in the C gamma 2 gene.

Finding complex oscillatory phenomena in biochemical systems. An empirical approach

Starting with a model for a product-activated enzymatic reaction proposed for glycolytic oscillations, we show how more complex oscillatory phenomena may develop when the basic model is modified by addition of product recycling into substrate or by coupling in parallel or in series two autocatalytic enzyme reactions. Among the new modes of behavior are the coexistence between two stable types of oscillations (birhythmicity), bursting, and aperiodic oscillations (chaos). On the basis of these results, we outline an empirical method for finding complex oscillatory phenomena in autonomous biochemical systems, not subjected to forcing by a periodic input. This procedure relies on finding in parameter space two domains of instability of the steady state and bringing them close to each other until they merge. Complex phenomena occur in or near the region where the two domains overlap. The method applies to the search for birhythmicity, bursting and chaos in a model for the cAMP signalling system of Dictyostelium discoideum amoebae.

Induction of ornithine decarboxylase and histidine decarboxylase activities in rat colon mucosa after application of 12-o-tetradecanoylphorbol-13-acetate (TPA), sodium deoxycholate and indole

Ornithine decarboxylase (ODC) and histidine decarboxylase (HDC) activities of rat colon mucosa were induced after intrarectal instillation of 12-o-tetradecanoylphorbol-13-acetate (TPA) and sodium deoxycholate. After instillation of sodium deoxycholate, ODC and HDC activities increased rapidly and reached a peak at 4 h, then decreased quickly towards control levels. Both enzymes activities also increased significantly 4 h after instillation in animals treated with TPA and sodium deoxycholate plus indole. However, there were no changes in ODC and HDC activities from 0-8 h after indole administration. These data are the first to show the induction of HDC activity in colon mucosa by TPA and sodium deoxycholate and suggest that the induction of activities in these two enzymes might be one mechanism of their action as cancer promoters.

Induction of beta-glucuronidase activity during dimethylhydrazine carcinogenesis and additive effects of cholic acid and indole

The kinetic change of beta-glucuronidase (beta-G) activity was measured in mouse large intestinal mucosa during dimethylhydrazine (DMH) carcinogenesis with addition of cholic acid and/or indole. The experiment lasted 21 weeks. The enzyme activity began to increase significantly at 5th week after treatment of DMH with cholic acid and/or indole, and at 7th week with DMH alone. Then, increased activity remained the rest of the time. Mouse intestinal cancer induced by DMH injection are also shown to have an increased beta-G activity. The induction of beta-G activity in the early stage of DMH colon carcinogenesis and additive effects of cholic acid and/or indole may imply one mechanism of action of DMH as a carcinogen and cholic acid as a promoter in large intestinal cancer.

Superoxide dismutase activity during dimethylhydrazine colon carcinogenesis and the effects of cholic acid and indole

Copper, zinc superoxide dismutase (Cu,ZnSOD) and manganese superoxide dismutase (MnSOD) activities were measured in mouse large intestinal mucosa during dimethylhydrazine (DMH) carcinogenesis. Mice were divided into five groups. Group A was subcutaneously injected with DMH (20 mg/kg) weekly and fed with a diet containing 0.2% cholic acid (C) and 0.8% indole (I). Group B was injected with DMH and given indole feeding. Group C was treated with DMH injection and cholic acid feeding. Group D was given DMH injection alone. Group E was an age-matched control group given 0.9% NaCl injection. The experiment last 21 weeks. The Cu, ZnSOD activity of intestinal mucosa in group A animals began to increase significantly at the 7th week of the experiment. In groups B, C and D, however, this enzyme was not elevated statistically until the 16th week, and then each of these groups kept an increased Cu,ZnSOD level the rest of the experimental period. MnSOD activity was elevated statistically in group C animals at the 7th week. The enzyme activity in group A and D animals increased at the 9th week, but the enzyme activity did not increase statistically until the 11th week in group B. After the 16th week of the experiment the increased activity of MnSOD in all experimental groups returned to the level of the control group. Large intestinal cancer tissues had increased Cu,ZnSOD activity and decreased MnSOD activity.

Xanthophylls and abscisic Acid biosynthesis in water-stressed bean leaves

Experiments were designed to obtain evidence about the possible role of xanthophylls as abscisic acid (ABA) precursors in water-stressed leaves of Phaseolus vularis L. Leaves were exposed to (14)CO(2) and the specific activities of several major leaf xanthophylls and stress-induced ABA were determined after a chase in (12)CO(2) for varying periods of time. The ABA specific radioactivities were about 30 to 70% of that of lutein and violaxanthin regardless of the chase period. The specific activity of neoxanthin, however, was only about 15% of that of ABA. The effects of fluridone on xanthophyll and ABA levels and the extent of labeling of both from (14)CO(2) were determined. Fluridone did not inhibit the accumulation of ABA when leaves were stressed once, although subsequent stresses in the presence of fluridone did lead to a reduced ABA accumulation. The incorporation of (14)C from (14)CO(2) into ABA and the xanthophylls was inhibited by fluridone and to about the same extent. The incorporation of (18)O into ABA from violaxanthin which had been labeled in situ by means of the violaxanthin cycle was measured. The results indicated that a portion of the ABA accumulated during stress was formed from violaxanthin which had been labeled with (18)O. The results of these experiments are consistent with a preformed xanthophyll(s) as the major ABA precursor in water-stressed bean leaves.

Acoustooptic filters for astronomical photometry: design and fabrication

Using calculations based on the acoustooptic properties of the crystal material a procedure is outlined for the design of filters having a particular bandwidth specification and reduced sensitivity to the incidence angle of the input beam. Relevant aspects of the fabrication techniques are given. The optical performance of a prototype filter having a 0.5-2-nm bandwidth over the 400-700-nm tuning range based on the design methods outlined is satisfactory for the chosen application, but it is not optimum. Analysis of experimental and design data shows that this can be accounted for by an error in the specified angle of the crystal axis which is required to accuracy of some +/-0 5 degrees .

Lack of genotoxic effects of fluoride in the mouse bone-marrow micronucleus test

The purpose of this investigation was to examine the potential genotoxic influence of sodium fluoride (NaF) on mammalian cells by means of a mouse bone-marrow micronucleus test. Mice of genotype B6C3F1 were obtained at about eight weeks of age and maintained on a low-fluoride diet (< 0.2 ppm F) and distilled water ad libitum throughout the experiment. At approximately 12 weeks of age, the animals were randomly assigned to seven groups, with multiple sampling schedules. The animals were intubated with various doses of NaF, ranging from 0.1 mg/kg to the Maximum Tolerable Dose (MTD), with sampling at 30, 48, and 72 hours after treatment. Negative (distilled water) and positive (cyclophosphamide) controls were included. Coded slides of femur marrow cells were prepared and examined, without identification as to treatments, for the frequency of micronucleated polychromatic erythrocytes (MN-PCE). The humera were analyzed for fluoride for monitoring of the absorption of fluoride following oral intubation. The results indicated that doses of NaF up to the MTD did not significantly increase the frequencies of MN-PCE when compared with the negative controls, although the bone fluoride content increased as the dose of NaF was increased.

Tissue-specific expression of the human alpha 1-antitrypsin gene is controlled by multiple cis-regulatory elements

Human alpha 1-antitrypsin (AAT) is expressed in the liver, and a 318 bp fragment immediately flanking the CAP site of the gene was found to be sufficient to drive the expression of a reporter gene (CAT) specifically in hepatoma cells. The enhancing activity however, was orientation-dependent. The DNA fragment was separated into a distal region and a proximal region. A "core enhancer" sequence GTGGTTTC is present within the distal region and is capable of activity enhancement in both orientations when complemented by the proximal region in the sense orientation. The results strongly suggest that there are multiple cis-acting elements in the human AAT gene that confer cell specificity for its expression. Nuclear proteins prepared from the hepatoma cells bound specifically to the proximal region in a band-shifting assay that was resistant to competition by the globin promoter DNA. Foot-printing analysis showed a protected domain within the proximal region that contains a nearly perfect palindromic sequence TGGTTAATATTCACCA, which may be important in the regulation of AAT expression in the liver.

Effects of fluoride on the mouse sperm morphology test

There has been little information and much confusion regarding the genotoxic effects of fluoride. The purpose of this study was to examine the spermatogenic influence of sodium fluoride (NaF) on the germ cells by means of the mouse sperm morphology test. Male mice of genotype B6C3F1 were obtained at about eight weeks of age and maintained on a low-fluoride diet (less than 0.2 ppm F) and distilled water ad libitum throughout the experiment. At approximately 13 weeks of age, the animals were randomly assigned to eight groups. Group I was intubated with the Maximum Tolerable Dosage (MTD) of NaF (70 mg/kg). Groups II through VI received NaF by stomach intubation at doses of 35, 20, 10, 1, and 0.1 mg/kg, respectively. Group VII served as a negative control and was intubated with distilled water. The positive control, Group VIII, was exposed to a known mutagen, cyclophosphamide (20 mg/kg, i.p.). The animals were treated daily for five days, and killed by cervical dislocation 35 days after the first exposure to chemicals. Slides of sperm from the cauda epididymides were prepared and blindly scored for morphological abnormalities. Weight of the testes was recorded, and the femurs were saved for fluoride (F) analysis. Analysis of bone F demonstrated the effective absorption of fluoride following intubation. The counts of abnormal sperm and the weights of the testes for mice exposed to NaF doses up to the MTD were not significantly different from those of the negative control. The results of this study showed that NaF did not have adverse effects on mouse sperm morphology.

Digital optical isochronous array processing

An optical isochronous array processing method is proposed. An optical isochronous array processor (OIAP) is a local regularly interconnected processing network that employs an array of identical optical processing elements. In an OIAP, incoming isochronous data are parallel processed in a fashion much like a propagating electromagnetic wavefront. For the various applications, the OIAP processing elements and their interconnections can be different. In this paper, various all-optical OIAP elements are considered. Applications ranging from optical binary number multiplication preprocessing to optical matrix algebra as well as to optical residue arithmetic are presented.