Isozyme and RAPD Analysis of the Genetic Diversity Within and BetweenVigna luteolaandV. marina

Nineteen accessions ofVigna luteola,five ofV. marinassp.oblonga,and two ofV. marinassp.marinawere analysed using variation ofisozymes and RAPD markers to obtain better insight into geneticrelationships within and between these taxonomic entities. Thirteenputative isozyme loci were scored, seven of which were polymorphic.Both species showed very low genetic diversity indices and mostof the variation was detected among populations. Pairwise Nei'sgenetic distances based on allozyme frequencies were also verylow and the accessions ofV. marinassp.marinawere the least relatedto the others. RAPD analysis was more discriminating and 66bands out of a total of 85 were polymorphic. Based on the presenceor absence of bands, Jaccard's similarity index was calculated.Similarity ranged from 0.476 to 0.98. Matrices derived fromboth isozyme and RAPD data were used to construct UPGMA dendrograms.In the tree obtained from Nei's genetic distance, based on allozymefrequencies, accessions belonging toV. marinassp.oblongaweremixed withV. luteolaaccessions; on the other hand, the twoV.marinassp.marinaclustered separately, with oneV. luteola.Thedendrogram derived from RAPD data showed three main groups correspondingto the three taxa analysed. Moreover, according to these data,V.marinassp.oblongais more closely related toV. luteolathan toV.marinassp.marina.Copyright 1997 Annals of Botany Company Vigna luteola(Jacq.) Benth.; Vigna marina(Burm.) Merrill; isozymes; RAPDs; genetic relationships; genetic variation     

Records of upwelling, seasonality and growth in stable-isotope profiles of Pliocene mollusk shells from Florida

Oxygen and carbon isotopic profiles across the shells of well-preserved bivalves and gastropods from the Pliocene Pinecrest Beds near Sarasota, Florida, provide detailed records of the paleoen-vironmental and paleoclimatic conditions under which these high-density shell beds accumulated, as well as offer insight into shell-growth rates and longevity. Eight turritellid gastropods were analyzed from within and surrounding two Turritella-rich beds, an upper bed within unit 2(2.5-2.0 Ma) and a lower bed situated near the top of the main shell bed, unit 6/7(3.5-2.5 Ma). Three bivalves plus another turritellid specimen from a lower horizon (middle of unit 6/7), considered to represent offshore, normal-marine conditions, were also analyzed. The isotopic profiles of all shells reflect year-round shell growth in a seasonal, subtropical to warm-temperate paleoenvironment. Cyclical patterns in δ¹⁸O reflect annual variations in water temperature which on average ranged from 15 to 24d?C; minimum paleoseasonality contrasts varied from 7 to 9d?C. Summer paleo-temperatures compare favorably with those detemined from ostracodes, whereas winter temperatures appear slightly cooler. Except for one pectinid specimen, temperature differences between horizons and specimens are small. Annual δ¹⁸O cycles indicate: Turritella apicalis lived longer and grew slightly faster than Turritella gladeensis; and, shell growth rates and increment formation in Mercenaria campechiensis are comparable to modern Florida populations. Coincident episodes of heavy δ¹⁸O and light δ¹⁸C in both turritellids and bivalves suggest a pattern of seasonal upwelling. This cool, nutrient-rich, upwelled water may be partially responsible for the great abundance of Pinecrest fossils. □Stable isotopes, Pliocene, Pinecrest Beds, Florida, upwelling, paleotemperature, mollusk, Turritella.      

Regeneration of Sclerenchyma in Wounded Dicotyledon Stems

When the sclerenchyma cylinder that surrounds the vascular cylinderin many dicotyledon stems is interrupted by cutting away oneside of an internode, its continuity becomes restored in somespecies by the differentiation of sclereids within the woundcallus. These sclereids, which may be scattered or arrangedin clumps or in a continuous sheet, lie in a zone within the‘cortical’ parenchyma between the regenerated vascularcylinder and the wound cork. The amount and especially the arrangementof regenerated sclerenchyma tends to reflect that of the originalprimary sclerenchyma cylinder in the unwounded stem, exceptthat longitudinal continuity is poorly developed and all fibresare replaced by sclereids. Syringa vulgaris L, lilac, regeneration, differentiation, fibres, sclereids, sclerenchyma, positional control     

DIAGNOSTIC SELF‐TESTING: AUTONOMOUS CHOICES AND RELATIONAL RESPONSIBILITIES

Diagnostic self‐testing devices are being developed for many illnesses, chronic diseases and infections. These will be used in hospitals, at point‐of‐care facilities and at home. Designed to allow earlier detection of diseases, self‐testing diagnostic devices may improve disease prevention, slow the progression of disease and facilitate better treatment outcomes. These devices have the potential to benefit both the individual and society by enabling individuals to take a more proactive role in the maintenance of their health and by helping society improve health and reduce health costs. However, the full implications of future home‐based diagnostic technology for individuals and society remain unclear due to their novelty. We argue that the development of diagnostic tools, especially for home use, will heighten a number of ethical challenges. This paper will explore some of the ethical implications of home‐based self‐testing diagnostic devices for the autonomous and relational dimensions of the person. This will be facilitated by examining the impact of diagnostic devices for individual autonomy, for the delivery of accurate diagnosis and for the personal significance of the information for the user. The latter will be examined using Charles Taylor's view of personhood and his emphasis on human agency and interpretation. While the ethical issues are not necessarily new, the development of home‐based self‐testing diagnostic devices will make issues regarding autonomy, accuracy of information and personal significance more and more demanding. This will be the case particularly when an individual's autonomous choices come into conflict with the person's relational responsibilities.     

Analysis of potential sources of variation in tissue culture derived celery plants

Somaclonal variation derived from tissue culture is a potential source of variation that can be used in crop improvement programmes. The characteristics of this variation are first shown in the regenerant generation and their heritability is then confirmed by examination of the progeny. There would be savings of time, space and labour if this variation could be detected in vitro using easily assessed visual cues. The aim of this study was to relate variation in the source of explant and the morphology of the newly initiated callus to the characteristics of the regenerant plant, of which the most important was resistance to leaf spot disease caused by Septoria apiicola. Associations were investigated by isolating four stem explants from each of 564 surface sterile seedlings, var. Celebrity, on a callus initiation medium (MS medium, 30 g litre‘¹sucrose, 0.5 mg litre’¹2,4-D, 0.6 mg litre‘¹kinetin) and assessing the morphology and colour of the callus. After this initial culture (8 wk), each callus was transferred to a regeneration medium (MS medium, 30 g litre“¹sucrose). Plantlets were regenerated from many of the callus cultures and these were transferred to the glasshouse. When all of the surviving regenerant plants (276) were mature, leaf shape, amount and composition of the essential oils and resistance to late blight were assessed. Statistical analysis revealed that the character of the newly initiated callus (width, height, colour, organogenesis) showed poor correlation with all aspects of the regenerated plant measured. However, it was shown that increased variation resulted from different seedlings more than from plants derived from within seedlings or within callus.     

Quantitative Measurement of Rates of 5S RNA and Transfer RNA Synthesis in Sea Urchin Embryos

Embryonic differentiation is believed to be due to a programmed expression of genes, which includes their time of activation, sequence of appearance, and amount transcribed into the immediate gene product, RNA. Differential synthesis of the major RNA classes, such as the ribosomal RNAs (28S, 18S, 5S) and transfer RNA (tRNA), characterizes many animal developing systems, including the sea urchin embryological system. Previous work has shown that the genes for 5S RNA and tRNA are active during early cleavage in sea urchin embryos. The present study focused on quantitatively measuring and comparing the rate of 5S RNA and tRNA synthesis in cleavage, early blastula, and early pluteus embryos of Arbacia punctulata. At each stage, embryos were labeled for 3 h with [8-³H]-guanosine. Total cellular RNA was extracted using the cold (4°C)-phenol-sodium dodecyl sulfate method and purified (LiCl-soluble) RNA preparations were fractionated by electrophoresis on 10% polyacrylamide gels. The amount of 5S RNA and tRNA synthesized at each stage was calculated from the radioactivity coincident with the 5S RNA and with the tRNA absorbance peaks (A_{260 nm}) on each gel, from the known guanosine monophosphate (GMP) compositions of sea urchin 5S RNA and tRNA and from the average specific radioactivity of the GTP precursor pool during each 3 h labeling period. The results showed that on a per embryo basis the rates of 5S RNA and tRNA synthesis increased slightly (about 1.4-fold) from cleavage through pluteus stages, while on a per cell basis the rates declined severalfold (about 3-fold) during embryogenesis. The rates of 5S RNA and tRNA synthesis determined here parallel previously-reported levels of RNA polymerase III in sea urchin embryos, suggesting that cellular levels of RNA polymerase III may exert some positive control over 5S RNA and tRNA synthesis during sea urchin embryogenesis.     

Transmission of Surface Pattern Through a Dedifferentiated Stage in the Ciliate Paraurostyla. Evidence from the Analysis of Microtubule and Basal Body Deployment

ABSTRACT. During conjugation of the hypotrich ciliate Paraurostyla weissei , the two partners fuse to form a transient dedifferentiated stage, the zygocyst, which later redifferentiates into a vegetative cell. Immunocytochemical studies have been performed to follow the deployment of microtubules and basal bodies during the entire cycle of conjugation. They show that a superficial lattice persists during the whole zygocyst stage, after most of the infraciliature of the exconjugants has been disassembled. These superficial microtubules display different immunocytochemical properties in the mature zygocyst and during its morphogenesis, suggesting that some transient chemical modifications of the microtubules are associated with the morphogenetic activity. In the zygocyst, the superficial microtubules retain the specific orientation characteristic of the ventral and the dorsal sides of the recipient cell, respectively. In the course of subsequent morphogenesis of the zygocyst, these specific cellular territories differentiate into the ventral and dorsal sides of the new cell. Although our experiments do not resolve the question of whether superficial microtubules play an active or merely a passive role in the transmission of surface pattern, they show that no complete breakdown in cell polarity occurs, even through a profound dedifferentiated stage. Thus, the overall surface pattern appears to be retained, in a simplified form, through the conjugation cycle.     

Attempts to define and mimic the effects of pollen on the development of lesions caused by Phoma betae inoculated onto sugarbeet leaves

Expanding lesions resulted when conidia of Phoma betae Frank, mixed with rye pollen, were inoculated on to sugarbeet leaves by a standard technique. Conidia without pollen generally caused non-expanding necrotic spots; these could be made to spread later by covering them with pollen or orange juice, but not with water. Germ-tube growth was quicker on water agar than on sugarbeet leaves. Pollen extract stimulated germ-tube growth on leaves 10 h after inoculation and resulted in the production of knots of hyphae overlying areas where intercellular hyphae could be discerned and where expanding lesions developed. Some inorganic salts mimicked the stimulatory effect of pollen on germtube growth on agar slides, but only a mixture of hexose sugars with boric acid reproduced the effect of pollen on both numbers and size of expanding lesions caused by P. betae on sugarbeet leaves, and numbers of expanding lesions caused by Botrytis cinerea Pers. ex Fr. on bean leaves.