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.

Human interstitial retinol-binding protein (IRBP): cloning, partial sequence, and chromosomal localization

A cloned 2184-bp cDNA coding for human interstitial retinol-binding protein (IRBP) has been isolated and sequenced. The probe hybridized to a 5.2-kb poly(A) RNA from human retinas. Nineteen tryptic peptides (363 amino acids) sequenced and purified from bovine IRBP could be aligned with 86-88% homology to the translated sequence. Two segments approximately 200 amino acids long were found to have a 41% residue identity, suggesting an internal duplication event. This cloned cDNA was used to probe DNA samples from a panel of 29 rodent-human somatic cell hybrids, mapping the structural gene for IRBP to chromosome 10. In situ hybridization suggested a regional localization near the centromere (p11.2----q11.2), although a secondary site of hybridization at q24----25 was also observed.

The chicken vimentin gene. Nucleotide sequence, regulatory elements, and comparison to the hamster gene

Here we report the nucleotide sequence of the chicken vimentin gene and its deduced primary amino acid sequence. A comparison of this gene to other intermediate filament protein genes demonstrates that both exon size and position are strongly conserved features of this multigene family. In addition, the hamster and chicken vimentin genes exhibit strong identity at the level of nucleotide (74%) and amino acid (80%) sequence. Interestingly, 40% of total sequence diversity is localized to the N terminus or "head" region of these genes whereas other protein domains (rod and C terminus) are remarkably identical in both nucleotide (81%) and amino acid (89%) sequence. Even stronger amino acid identity (100%) is exhibited in certain subdomains which may define regions crucial for filament formation and function. Not surprisingly, vimentin is more homologous across animal species than it is to other intermediate filament protein members (e.g. desmin) within the same species. A comparison of 5'-flanking sequences of the hamster and chicken genes as well as other characterized promoter elements (SV40, HSV-TK) reveals homologous sequence elements which may define common and/or unique sites involved in the modulation of gene expression. The implications of these sequence elements for both tissue-specific and developmental expression of the vimentin gene are discussed.

Conditional symbolic modified signed-digit arithmetic using optical content-addressable memory logic elements

A new conditional symbolic substitution rule for modified signed-digit arithmetic computation is introduced. Using this substitution rule, the numbers to be added or subtracted are first replaced by a pair of new equivalent strings, which in a second step are then subject to another substitution to generate both the addition or subtraction result and its complement. For an optical implementation, a holographic contentaddressable memory is used. Correspondingly, the input encoding, the logic reduction, and the optical processing techniques are described.

Bgl II RFLP recognized by a human IRBP cDNA localized to chromosome 10

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