Crop/Weed gene flow:Cucurbita argyrosperma Huber andC. fraterna L. H. Bailey (Cucurbitaceae)

A mixed population of Cucurbita at Vado El Mow in northern Tamaulipas, Mexico showed an anomalous pattern of fruit bitterness. Some domesticated plants (C. argyrosperma andC. moschata) expressed cucurbitacin bitterness whereas some sympatric free-living plants produced non-bitter fruits. This reversal of typical cucurbitacin expression suggested gene flow between crop and weed at the site. Isozyme analysis provided little insight as to taxa involved in gene exchange, although progeny from a single free-living plant carried IDH allozymes that are associated with Mexican landraces ofC. pepo. Synthetic hybridization revealed that fertile F, hybrids are produced from crosses involvingC. fraterna as the pistillate parent andC. argyrosperma as the staminate parent. Interspecific crop/weed hybrids can produce viable progeny upon self-pollination or backcrossingto either parent, andF₂ families display normal allozyme segregation. Hybrid fertility, as indicated by pollen stainability, increases in progeny produced by backcrossingfrom theC. argyrosperma parent. Interspecific hybridfertility represents a potential for crop/weed gene flow that would be realized under natural conditions if pollen flow occurs betweenC. fraterna andC. argyrosperma in the fields of Tamaulipas. Oligolectic “squash bees” (Teponapis), efficientCucurbita pollen vectors, are present at the site. Thus, it is likely that natural interspecific crop/weed hybridization has occurred at Vado El Moro and this might at least partially explain the anomalous distribution of fruit bitterness among extant populations at the site.     

Flow cytometric estimation of nuclear DNA amount in diploid bananas (Musa acuminata andM. balbisiana)

Cell nuclei were isolated from leaf tissues of wild banana (Musa balbisiana, M. acuminata ssp.banksii andM. acuminata ssp.errans) and of the two vegetative clones of diploid cultivar “Pisang Mas”. Relative fluorescence intensity was measured on propidium iodide-stained nuclei by flow cytometry. Nuclei isolated fromGlycine max with known nuclear genome size were used as internal standard to determine nuclear DNA content ofMusa in absolute units. The results of the study showed that the size of nuclear genome ofMusa is smaller than previously estimated. In general, it is smaller in comparison with many other angiosperms. Furthermore, it was found that nuclear DNA content ofM. balbisiana (genome BB) is significantly lower than that ofM. acuminata subspecies and cultivars (genome AA). This finding should permit estimation of genome composition in triploidMusa clones with expected hybrid composition. Flow cytometry is proposed as a useful technique with potential applications in taxonomy, breeding and biotechnology ofMusa.     

Alcohol dehydrogenase isoenzymes fromNicotiana tabacum include ADH of bothN. sylvestris andN. tomentosiformis

Electrophoretic separation of seed alcohol dehydrogenase (ADH) fromNicotiana tabacum on 12% starch gels at pH 7.8 produced only one band with an apparent R_f of 0.65, which confirmed earlier reports. The same was found with pollen ADH. However, in polyacrylamide gel isoelectric focusing, seed ADH separated into three distinct bands with apparent pI of 5.33, 5.42 and 5.50. The pI 5.33 isoenzyme was found to be the essential form inN. sylvestris seeds. The analysis of charge properties ofN. tomentosiformis seed ADH showed only one isoenzyme with pI of 5.56. These results present further evidence thatN. tabacum has arisen from a cross between aN. sylvestris predecessor and an ancestral type ofN. tomentosiformis. The presence of the pI 5.42 form inN. tabacum is consistent with the reported formation of heterodimeric ADH in tobacco hybrids.     

Oil concentration and fatty acid composition of achenes of North AmericanHelianthus (Asteraceae) species

Oil concentration and fatty acid composition were determined in achenes of two annual Helianthus species (112 populations) and 11 perennial species (103 populations) from the Great Lakes region and the Central Great Plains of the U.S. The highest average oil concentration was observed in annualH. petiolaris Nutt. with 28.8%, followedbyH. annuus L. with 25.4%. Among the perennial species,H. hirsutus Raf. had the highest average oil concentration with 29.8%. The highest average palmitic (C16: 0) andstearic (C18:0) fatty acids were observed inH. tuberosus L. (6.5 and 3.5%, respectively), while the lowest values were observed inH. pauciflorus Nutt. ssp.subrhomboideus (4.2 and 2.1, respectively). The highest oleic acid (CI8:1) was observed inH. annuus (24.7%) and the highest linoleic (C18:2) was observed inH. pumilus Nutt. with 71.3%. Sufficient variability appears to be present in the wild species for enhancement of oil and fatty acid characteristics for cultivated sunflower.     

Subcellular localization of ribonuclease isoenzymes in tobacco mesophyll protoplasts and their changes induced by infection of PVY

Changes in the content and subcellular localization of ribonuclease isoenzymes were determined in mesophyll protoplasts prepared fromNicotiana tabacum L. cv. Samsun from healthy and potato virus Y (PVY) infected plants. Intact chloroplasts, mitochondria and soluble cytosolic proteins were obtained after protoplast disintegration by means of differential centrifugation. The 1 000g pellet from healthy protoplasts contained 7.3 %, the 15 000g pellet 13.5 % and 15 000g supernatant 82.1 % of the total activity of ribonucleases. The 1 000g pellet from infected protoplasts contained 10.4%, the 15 000g pellet 10.0% and 15 000g supernatant 89.6 % of the total activity of ribonucleases. The activity of these enzymes in infected protoplasts was enhanced in crude homogenate to 137.0 % (P<0.001), in 1 000g pellet to 194.8 % (P<0.001), in 15 000g pellet to 101.3 % (NS), and in 15 000g supernatant to 149.4 % (P<0.001) of that in healthy noninoculated protoplasts.     

Effects of inorganic arsenicals on DNA synthesis in unsensitized human blood lymphocytes in vitro

Effects of inorganic arsenicals on DNA synthesis in unsensitized human blood lymphocytes were biphasic: The chemicals at very low concentrations enhanced DNA synthesis, whereas higher concentrations inhibited DNA synthesis. The concentrations of arsenicals at which the maximum stimulating effect was found were 1×10^?5 M, 1×10^?6 or 2×10^?6 M, and 0.8×10^?6 or 1×10^?6 M for sodium arsenite exposure of 1 h, 3 d, and 6 d, respectively; for sodium arsenate, 1× 10^?5 M, 1×10^?5 M, and 2×10^?6 or 5×10^?6 M, respectively. Arsenicals must be present for the entire 6-d culture period to produce maximum stimulation of DNA synthesis in human lymphocytes. The longer exposure of the lymphocytes to arsenicals, the lower the concentrations of arsenicals at which the maximum stimulating effect on DNA synthesis was found. Stimulating effect of trivalent arsenic (sodium arsenite) on DNA synthesis was stronger than pentavalent arsenic (sodium arsenate), and the stronger the effect of trivalent arsenic than pentavalent, the longer exposure of the cells to the chemicals. Both sodium arsenite and sodium arsenate stimulated DNA synthesis in human lymphocytes to a lower degree than phytohemagglutinin (PHA).     

Characterization of mitochondrial DNA topoisomerase I fromNeurospora crassa

DNA topoisomeraseI isolated from the lower eukaryoteNeurospora crassa mitochondria was characterized. Molar mass of the enzyme in the native state is 120 kDa and 60–65 kDa when denatured. The pH optimum of the enzyme is 7.8 and the KCl optimum concentration is 40 mmol/L. This topoisomerase is independent of ATP and Mg²⁺. N-Ethylmaleimide, 4-chloromercuribenzoate, SDS, guanidinium chloride, polyethylene glycol, heparin and ethidium bromide inhibit its activity, while novobiocin, nalidixic acid, Triton X-100 and chloroquine do not. Polyamines, and histone, H1 stimulate the topoisomerase activity. We classify this DNA topoisomerase as typeI and eukaryotic. Conversion of the topoisomerase to a nonspecific endonuclease at increased temperature is proposed.     

Plant radioresistance and DNA repair efficiency inChlamydomonas reinhardtii andPisum sativum

This paper compares the repair of DNA single strand breaks (ssb) induced by γ-radiation in two strains ofChlamydomonas reinhardtii (137C/+/ and UVS-I) and three lines ofPisum sativum (NN 131, 198, 140) differing in the degree of radioresistance. DNA ssb in cells exposed to γ-rays (50, 100, 200, 500 Gy) were measured by electrophoresis and alkaline unwinding method with subsequent chromatography on hydroxyapatite immediately after irradiation and after 30 min of post-irradiation incubation at 25°C. An increase of double-strand DNA (in%) was found in cells after 30 min post-irradiation incubation.C. reinhardtii strains displayed an equal level of DNA degradation and repair efficiency in the DNA single strand breaks. The radioresistant line N 198 ofP. sativum is characterized by a lower level of induced DNA ssb and higher efficiency of repair of these breaks as compared with less radioresistant lines NN 131 and 140.     

Cytological relationships of selected species ofPanicum L.

The cytological investigation of 12 taxa ofPanicum L. revealed that the vast majority of them have the basic number x=9 at different ploidy levels. The basic number x=8 was recorded only in the tetraploid speciesP. maximum with 2n=32. The diploid number 2n=18 was encountered inP. capillare, P. laevifolium, P. antidotale andP. coloratum (2) with 3B-chromosomes recorded in the latter species. The tetraploid chromosome number 2n=36 was found to exist inP. miliaceum, P. miliare, P. coloratum (1) andP. virgatum. The hexaploid number 2n=54 was recorded inP. bulbosum, P. dichotomiflorum andP. esculentum. The karyotypes of all accessions were mostly symmetrical and mainly comprised of meta- and submetacentric chromosomes with little variation in length among them within each karyotype. Investigation of chromosome association during metaphase I of meiosis revealed that the frequency of bivalents/cell was the highest among all investigated diploid, tetraploid and hexaploid accessions. Univalents were also frequently encountered in various accessions. These results may indicate that segmental alloploidy has been the major process by which polyploid species have originated.     

Diversity in two candidate malaria vaccine antigens in different Indian strains ofPlasmodium falciparum

Polymorphism in two malarial antigens, merozoite surface antigen-1 (MSA-1) and ring erythrocyte surface antigen (RESA), has been characterized in four different Indian strains ofPlasmodium falciparum. The Indian strains were obtained from two malaria endemic regions of India, viz. Surat (Gujarat) and Delhi, and established in culture. Monoclonal and polyclonal antibodies raised against different domains of these antigens were used in the study. In MSA-1 a novel intragenic crossover was detected in the central conserved domain in two of the Indian strains. The repeat domain of RESA was found to be absent in the two strains ofP. falciparum isolated from Surat. These differences in immunoreactivity have been extended to the DNA level by appropriate PCR studies. MSA-1 and RESA are candidate vaccine antigens and these diversities will have an important bearing on the design of a suitable malaria vaccine.     

Cryptorchidie et cancer du testicule

A history of cryptorchidism is the only risk factor for testicular cancer that can be considered unequivocally established. The rate of cryptorchidism at age 3 months appears to have increased over the 30 years from 1.7% to 3.2%. From a review of the literature, the overall proportion of testicular cancer patients with a history of cryptorchidism is approximately 10%. Case-control studies indicate that the relative risks of testicular cancer associated with a history of cryptorchidism are about 6. Prevalence of testicular cancer in patients with a history of cryptorchidism could range between 2% and 3%, as reported in studies from North European Countries. Orchidopexy itself or age at orchidopexy seem to have no effect on the subsequent risk of testicular cancer; however, data from the literature are somewhat discrepant. But orchidopexy does seem to influence the histologic type of malignancy, with a lower frequency of seminoma. The developement of non invasive techniques is badly needed to allow population screening for testicular cancer.     

A search for mutations that affect the non-oxidative pentose phosphate pathway inSaccharomyces cerevisiae

A number of selection strategies have been devised to obtain mutations in the non-oxidative pentose phosphate pathway in the yeastSaccharomyces cerevisiae. Some of these schemes exploit the bidirectionality of this pathway by selecting for mutants that can grow on a mixture of two carbon sources, which allow the pathway to function in opposite directions, while failing to utilize either of them alone. Other strategies select for mutations that prevent growth on glucono-5-lactone or xylulose, compounds metabolized exclusively through the pentose phosphate pathway. In the present study, these schemes yielded 35 mutants that define 11 genetic complementation groups. None of these mutations, however, affected the activity of the pathway enzymes, assayed in cell-free extracts. Nevertheless, the mutants were deficient in various aspects of carbohydrate metabolism and in the biosynthesis of the aromatic amino acids. The problems associated with the selection of mutants directly affected in the functioning of the enzymes of the non-oxidative pentose phosphate pathway have been discussed.     

Procréation médicalement assistée et paraplégie masculine — Expérience Montpellieraine

Between 1980 and 1993, seventy one tetra or paraplegic patients consulted in order to know more about their “procreative status”. After being taken into care in an appropriate enviroinment, specialized in the treatment of ejaculation disorders and following a semen analysis, twenty two patients decided to procreate. Their vertebral lesions were located in the cervical region (5 cases), drom D1 to D10 (10 cases), from D11 to L1 (6 cases) and from L2 to L5 (1 case). Eighteen patients suffered from complete lesions. Nineteen patients achieved an ejaculation: fifteen cases of antegrade ejaculations, three cases of retrograde ejaculations and one mixed one. Out of eighteen pregnancies — for fourteen couples — nine were obtained in Assisted Reproductive Technology: three of them after an intravaginal artificial insemination, one following an intracervical artificial insemination, two after an intrauterine artificial insemination, two through an in vitro fertilization (IVF), one following a transfer of frozen embryos obtained through IVF with some epididymal spermatozoon. An Assisted Reproductive Technology strategy is being proposed, which takes into account the number of available progressive moving spermatozoon.     

Synergistic interaction between particular X-chromosome deletions andSex-lethal causes female lethality inDrosophila melanogaster

We studied the effect on female viability oftrans-heterozygous combinations of X-chromosome deficiencies andSxl ^f1, a null allele ofSex-lethal. Twentyfive deficiencies, which together covered 80% of the X chromosome, were tested. Seven of thesetrans-hcterozygous combinations caused significant levels of female lethality. Two of the seven interacting deficiencies include the previously known sex determination genessans fills andsisterless-a. Four of the remaining uncover X-chromosomal regions that were not hitherto known to contain sex determination genes. These newly identified regions are defined by deficienciesDf(1)RA2 (7D10; 8A4-5),DJ(1)KA14 (7F1-2; 8C6),Df(1)C52 (8E; 9C-D) andDf(1)NI9 (17A1; 18A2). These four deficiencies were characterized further to determine whether it was the maternal or zygotic dosage that was primarily responsible for the observed lethality of female embryos,daughterless andextra macrochaetae, two known regulators ofSxl, influence the interaction of these deficiencies withSxl.     

The ethnobotany of sweet flag,acorus Calamus (Araceae)

Sweet flag,Acorus calamus, one of the few extratropical members of the Araceae, is a semi-aquatic component of aquatic habitats throughout the temperate to sub-temperate regions of Eurasia and the Americas. The plant has a rich ethnobotanical history dating back possibly to the time of Moses in the Old Testament of the Bible and in early Greek and Roman medicine. Sweet flag, thought to be indigenous to India and spread along trade routes, has been valued for its rhizome and fragrant oils which have been used medicinally, in alcoholic beverages, as a fragrant essence in perfumes and oils, and for insecticidal properties. Current research investigates sweet flag’s value as an insecticidal, antibacterial and antifungal agent. This paper is a comprehensive survey of the past, present and future uses of sweet flag.     

Enzyme activities ofChlorophyllum molybditis andCortinarius melliolens at different sporophore stages

The intracellular enzyme activities ofChlorophyllum molybditis (Mayerex. Fr.) Massee andCortinarius melliolens Fries were determined at different stages of sporophore maturity. In both mushroom species, total amylase, α-amylase, proteinase, lipase, peroxidase, catalase and polyphenol oxidase activities were increased with sporophore maturity. In contrast, glucose-6-phosphatase activity was higher in the young sporophore than in very young and mature ones. All the enzymes assayed except cellulase and β-amylase showed greater activity in the pilei than in the stipes.C. molybditis showed greater total amylase, α-amylase, cellulase, proteinase, catalase and glucose-6-phosphatase activities thanC. melliolens.     

Enhancement of faba bean nodulation,nitrogen fixation and growth by different microorganisms

The effect of four bacterial and six fungal species on nodulation and growth ofVicia faba cv. Giza 3 inoculated withRhizobium leguminosarum biovarviceae strain RCR 1001 were assessed in a pot experiment.Bacillus cereus, Pseudomonas fluorescens, Aspergillus niger andA. quadriliniatus either alive cells or sterile filtrate significantly promoted nodulation, growth and nitrogen accumulation. Heat-killed cells had no effect.     

Mitochondrial DNA restriction maps ofMus booduga,Mus terricolor andMus musculus tytleri

Restriction maps of milochondrial DNA of the Indian pygmy field miceMus booduga andM. terricolor, and the house mouseM. musculus tytleri were determined with seven six-cutter restriction enzymes. The restriction map of the mitochondrial DNA of the laboratory mouseM. m. domesticus was used as a reference. Pairwise comparison was made of the mitochondrial DNAs for the presence or absence of the restriction sites, and per cent sequence divergence was calculated. The results show that the sequence divergence betweenbooduga andterricolor is 8-7% while thedomesticus-tytleri andbooduga-terricolor groups are divergent by 16-3%. The mtDNA sequence divergences we have obtained suggest that thebooduga-terricolor lineage might not have diverged before the Southeast Asiancervicolor-cookii-caroli lineage during evolution of these lineages of the subgenusMus as inferred by others earlier. On the other hand, it seems likely that these lineages evolved in parallel.