Rates of corolla growth in tobacco determined with the plastochron index

The growth of vegetative and reproductive shoots of Nicotiana tabacum L. cv. Xanthi is analyzed with the plastochron index to estimate the relationship between corolla growth and time. The plastochron of leaves 9 through 20 declines steadily at each successive node. The flower plastochron increases steadily during the growth of an individual cyme, with the most distal flower to open having the longest plastochron. Variation in the flower plastochron is the result of variation in the rate of flower initiation, not the growth rate of individual flowers. The corolla has an extended phase of approximately constant relative growth in length (between 0.2 · d^–1 and 0.3 · d^–1) until a peak of growth (0.5 · d^–1) 2–3 d before anthesis. Corollas also have periodic peaks and troughs of growth that are low in amplitude (0.1 · d^–1), but persist throughout most of corolla development. The pattern of corolla expansion contrasts strongly with earlier reports of the pattern of tobacco leaf growth.Abbreviations PI plastochron index - PR plastochron ratio - RGR relative growth rate in length The authors thank: Drs. T. Sage and E.G. Williams for the considerable time and space they invested; the members of Dr. R. Wyatt's laboratory for allowing us to use their computer facilities; A. Tull and M. Smith for their care taken in the green-house. This research was supported by U.S. Department of Agriculture grant GAM-89-01056 and by National Science Foundation grant DCB-87-15799.     

Group size and stability: Why do gibbons and spider monkeys differ?

Gibbons and spider monkeys have similar diets, body size, and locomotor patterns. They are therefore expected to be subject to similar socioecological rules. However their grouping patterns differ. Gibbons live in small stable groups, whereas spider monkey form unstable sub-groups that vary from small to large during different seasons. If similar principles apply to the two species, food abundance should vary more for spider monkeys than for gibbons; food density should be similar for the two species when spider monkey sub-groups are the same size as gibbon groups; and the highest level of food abundance should be higher for spider monkeys than for gibbons. These predictions are upheld for a comparison of particular populations ofHylobates muelleri andAteles geoffroyi.     

Prediction of F3 row performance from F2 individual plant data in oats

Summary Parameters estimated from a Gardner-Eberhart analysis of the F₂ generation of a six-parent diallel in oats (Avena sativa L.) were used to compare methods for predicting the performance of F₃ row plots. The prediction methods were: (1) individual F₂ plant performance (F2I), (2) parent average plus F₂ plot deviations (PF2), (3) parent average plus weighted F₂ plot deviations (PF2P), (4) best linear unbiased prediction (BLUP) of parent average plus F₂ plot deviations (BPF2), and (5) BLUP plus weighted F₂ deviations (BF2). The F₂ single-plant traits used for prediction were biological yield to predict F₃ biological yield, whole plant and primary tiller grain yield for prediction of F₃ grain yield, and whole plant and primary tiller harvest index (HI) to predict F₃ HI. Prediction methods were evaluated by correlations between predicted and observed F₃ performance. Prediction methods and traits for which correlations were greater than for F2I included: BF2 for biological yield, PF2, PF2P and BF2 for whole plant grain yield, PF2, BPF2, and BF2 for primary tiller grain yield. None had a correlation significantly greater than F2I for either measure of HI, where heritability was large. PF2 is the recommended method for traits with low heritability because of its simplicity and because it had the largest or nearly the largest correlation for each of the yield traits. F2I is the recommended method for traits with larger heritability.Contribution No. 8821 of the U.S. Regional Pasture Research LaboratoryDeceased     

Paracrinology of growth regulation

Embryonic and fetal growth is dependent on genetic factors and epigenetic factors such as peptide growth factors. We describe here the interactions of several peptide growth factors during the growth and function of two cell types, growth plate chondrocytes from the ovine fetus and astroglial cells from the newborn rat cerebral cortex. Isolated chondrocytes released two endogenous growth factors, basic fibroblast growth factor (bFGF) and insulin-like growth factor II (IGF II). Although the latter was released in greater abundance, as detected by radioimmunoassay, exogenous bFGF was more than a thousand fold more active as a mitogen. Insulin was also able to increase chondrocyte replication at physiological concentrations, and bFGF, insulin and IGFs were additive in their effects on DNA and protein synthesis. Transforming growth factor beta (TGF beta), which is abundant in bone, had little effect on chondrocyte DNA or total protein synthesis alone, but blocked the stimulatory actions of insulin and IGFs on these parameters. However, TGF beta when alone or in combination caused an increase in the collagen: non collagenous protein ratio of new proteins synthesized by chondrocytes. Adult rat brain is a rich source of IGF II, and both IGF I and II are present during neurogenesis and gliagenesis in the fetal and neonatal rat respectively. We have cultured astroglial cells isolated from neonatal rat cerebral cortex to examine the production and interaction of peptide growth factors during their growth. Isolated astroglial cells contained mRNAs encoding both IGF I and II but abundance was not regulated by other hormones or growth factors. Using affinity cross-linking we found that cultured cells also released two species of IGF binding protein (IGF-BP) of 33 kDa and 38 kDa. Northern blot analysis using homologous cDNA probes showed that astroglial cells expressed IGF-BP2 and BP3, but little BP1. Both IGF I and II were mitogenic for astroglial cells, as was insulin at physiologic concentrations. Exogenous IGF-BP2 was able to modulate the mitogenic actions of exogenous IGF I. These two very different cell models show many similarities of endogenous growth control. Both release IGFs and IGF-BPs which regulate mitogenic rate. In addition, in both insulin functions as a growth factor at physiologic concentrations. These findings suggest common principles governing embryonic and fetal growth and development. Studies have shown that fetal and neonatal growth is independent of regulation by classic hormones (e.g. growth hormones) synthesized by the mother or the fetus. It is believed that embryonic and fetal growth is controlled by two major mechanisms, namely, (i) the genetic factors as determined by the embryonic and fetal genome, and (ii) the epigenetic and environmental factors that alter the expression of the embryonic or fetal genome.(ABSTRACT TRUNCATED AT 400 WORDS)     

Oestrogen receptor gene structure and function in breast cancer

The mechanisms underlying loss of oestrogen responsiveness in breast cancer are not well-defined. Potential mechanisms include loss of receptor expression, alterations in the oestrogen receptor (ER) gene producing proteins with abnormal function, or changes to receptor-dependent or -independent pathways controlling cell proliferation. Examination by Southern analysis of the ER gene in a series of ER-negative and -positive breast tumour biopsies failed to provide evidence of gross rearrangements and in only only one of thirty seven tumour DNA samples was significant gene amplification observed. No restriction fragment length polymorphisms were detected for the restriction enzymes EcoRI, Pst I or Hind III. Methylation of the ER gene as assessed by Hpa II and Msp I restriction enzyme digests varied between tumours but the degree of methylation was not correlated with levels of expression of the receptor protein. Similar findings applied in a series of ER-negative and -positive breast cancer cell lines and clonal lines of MCF-7 cells, which were developed as an in vitro model for the acquisition of oestrogen and antioestrogen resistance. In this model there was no evidence that changes to ER receptor function and/or structure at the level of the ER gene, mRNA, ligand binding, and ability to induce progesterone receptor might account for the development of hormone resistance. However, the ability of ER to interact with a DNA sequence containing the vitellogenin promoter oestrogen response element, as assessed by gel retardation assay, was impaired in the clone showing the greatest degree of oestrogen and antioestrogen resistance.     

Biochemical characterization of transgenic tomato plants in which carotenoid synthesis has been inhibited through the expression of antisense RNA to pTOM5

Transgenic tomato plants expressing antisense RNA to a ripening-related cDNA clone (pTOM5) had yellow ripening fruit and pale coloured flowers. Carotenoid levels in fruit of these plants were reduced by up to 97%. In order to determine the step of carotenoid biosynthesis which was blocked, a cell-free system active in the synthesis of carotenoid intermediates was prepared. Incubations with radiolabelled carotenoid precursors led to the identification of the block between GGDP and phytoene. Analysis of carotenoids in different tissues of transgenic and control plants indicated that although ripe fruit and flower carotenoid levels were reduced in the modified plants, leaf carotenoid levels were not decreased. This implies that the pTOM5 gene product is not involved in carotenoid synthesis in the leaf.     

The acetycholinesterase gene ofAnopheles stephensi

1. The acetylcholinesterase (AChE) gene from the important malaria vector Anopheles stephensi has been isolated by homology to the Drosophila acetylcholinesterase gene. 2. The complete sequence and intron-exon organization has been determined. The encoded protein has 69% identity to Drosophila AChE and 38 and 36% identity to Torpedo AChE and human butyrylcholinesterase, respectively.     

In situ activation of mouse macrophages and therapy of spontaneous renal cell cancer metastasis by liposomes containing the lipopeptide CGP 31362

Summary We determined whether the intravenous administration of multilamellar vesicle liposomes (MLV) containing a lipopeptide analogue of a fragment from the cell wall of gram-negative bacteria (CGP 31 362) can render BALB/c mouse alveolar macrophages tumoricidal in situ and reduce the incidence of spontaneous lung metastasis of syngeneic renal carcinoma (RENCA) cells. Alveolar macrophages (a) incubated in vitro with MLV containing CGP 31 362 (MLV-31 362) and (b) harvested from mice injected i.v. with MLV-31 362 were rendered cytotoxic against the RENCA cells. Maximum cytotoxic activity of the macrophages was induced by injecting 5 µmol MLV consisting of 250 mg phospholipids and 0.5 mg CGP 31 362. The single i.v. injection of 5 µmol MLV-31 362 produced activation of macrophages that lasted for up to 4 days. Repeated i. v. injections of MLV-31 362 produced a continuous antitumor activity in alveolar macrophages. To study the lipopeptide's effects on metastasis, we injected the left kidneys of BALB/c mice with RENCA cells. The kidney with growing tumor was resected 10 days later and, after a further 2 days, groups of mice were injected i.v. with MLV-31 362 or with MLV-HBSS (twice weekly for 3 weeks). Treatment with MLV-31 362 significantly decreased the median number of spontaneous lung metastases. These data demonstrate that the systemic administration of MLV-31 362 can activate murine lung macrophages in situ and reduce the incidence of spontaneous RENCA lung metastases.     

Lymphocyte activation and serine-esterase induction following recombinant interleukin-2 infusion for lymphomas and acute leukaemias

Summary C57BL mice inoculated with radiation leukemia virus (RadLV) develop preleukemic cells long before the onset of leukemia. These cells are potentially immunogenic but fail to elicit an immune response in the host because of the appearance of virus-specific suppressor T cells. We have studied the effect of polysaccharide K (PSK) on the generation of RadLV-specific cell-mediated immune responses in vitro. Long-term exposure to PSK in culture potentiated the ability of immunized T cells to respond to a RadLV-induced lymphoma. It also abrogated the suppressive activity of suppressor T cells and simultaneously boosted the ability of reactive T cells to respond. The dual immunostimulating activity of PSK resulted in the generation of T cytotoxic lymphocytes that could lyse lymphoma cells in vitro. The results suggest that PSK could be used as a prophylactic immune response modifier in preleukemia.     

Comparison of methods of repelling mosquitoes

Comparisons were made with human subjects of repellency of free flying Anopheles gambiae using soaps containing deet and permethrin or permethrin alone. The reduction in biting did not differ statistically significantly between these two forms of repellent soap. Some mosquitoes which touched the permethrin soap layer without biting died within the next day. The soap with deet was compared with the same amount of deet in a commercially available stick or as a liquid. Only in the latter form did the repellent show resistance to being washed off by cold water.Electrically heated vaporizing mats containing bio-allethrin were shown to be more effective than smouldering coils containing natural pyrethrins, in that there was more complete prevention of biting, and more rapid knock-down and kill. Operation of the vaporizing mat caused deposition of insecticide on the room surfaces.