ANTHER MORPHOLOGY AND THE ORIGIN OF THE TETRAPLOID WHEATS

Anther morphology of various species of the genus Triticum is consistent with previous evidence that different biotypes of T. boeoticum (AA) and T. urartu (BB) contributed the respective A and B genomes to the emmer (A^eA^eB^eB^e) and timopheevi (A^tA^tB^tB^t) tetraploid complexes. Anther length of T. dicoccoides (2.8 mm) and T. araraticum (3.0 mm) is mid-way between that of T. boeoticum (3.6) and T. urartu (2.2) and the same as that of the sterile hybrid T. boeoticum X T. urartu. With respect to mode of dehiscence, post anthesis reflexion of anther lobes and twisting of the anthers, T. dicoccoides resembles T. boeoticum, whereas T. araraticum resembles T. urartu. With respect to anther apex, T. dicoccoides resembles neither T. boeoticum nor T. urartu but is identical with their F₁ hybrid. Among amphiploids involving four different Aegilops species and T. boeoticum lines, none could similarly account for the length or other diagnostic attributes of the tetraploid anthers. Anther morphology is consistent with the presumed genomic composition of the cultivated tetraploid and hexaploid wheats and seems to distinguish effectively the different genomic groups of the genus Triticum.     

Task demand as reflected in catecholamine excretion and heart rate.

Immediate effects and aftereffects of exposure to a color-word conflict task were studied in two groups of subjects, one of which performed the task without auditory interference ("single conflict"), the other with auditory interference ("double conflict"). Physiological arousal indices were more susceptible than performance measures to the level of task demand. Thus, the higher demand imposed by the double-conflict task was reflected in relatively larger increases of adrenaline excretion and heart rate, both during the conflict task and during the subsequent arithmetic task, whereas the performance measures remained unaffected.     

Mast cell activation and tissue cell proliferation

Summary The effect of mast cell activation and degranulation on the proliferation in the intact mesentery was studied in Sprague-Dawley rats. Mast cell activation was achieved by a single intraperitoneal injection of Compound 48/80.The proliferation was studied using three independent methods for estimation of cell production and DNA synthesis: 1. the mitotic index, 2. the relative number of cells having a DNA content in the S and G2 regions, by Feulgen photometric measurement in individual cells, and 3. the specific DNA activity, employing a method which combines a liquid scintillation technique after an intravenous injection of ³H-thymidine and Feulgen photometric determination of the DNA content per membrane preparation.It was found that the proliferation of the normal mesenchymal cells adjacent to the activated and degranulated mast cells in the mesentery was significantly increased within 24 and 32 h, the maximum increase being more than 20-fold compared to untreated controls. The results suggest that the common type of mast cell may have a pathophysiological function related to stimulation of local cell proliferation.Supported by grants from the Swedish Medical Research Council (Project 12X-2235) and from the Medical Faculty, University of LinköpingWe thank Brita Söderlund, Margareta Odenö and Iréne Svensson for skilful technical assistance, and Erik Leander, Ph. D., for help with statistical methodsPart of this work was presented at the 7th Meeting of the European Study Group for Cell Proliferation, 5–9 May 1975, in Amsterdam, The Netherlands     

Release of cyclic AMP from the superfused prepubertal rat ovary stimulated with human chorionic gonadotrophin (HCG) and prostaglandin E1 (PGE1).

The release of cAMP and lactate from the HCG and PGE₁ stimulated prepubertal rat ovary has been studied using a superfusion technique. The continuous presence of HCG (50 IU/ml) or PGE₁ (10 μg/ml) in the medium led to an increased but transient release of cAMP. The release of lactate also rose as a consequence of the stimulus but in this case the release stayed at an elevated level during the whole experimental period. Experiments with HCG (10 IU/ml) applied as 40-minute pulses spaced 240 minutes apart showed the ovaries to be refractory to the second stimulus. Contrary to this PGE₁ (10 μg/ml) administered under the same conditions elicited a renewed response to the second pulse. Despite refractoriness to a second HCG pulse, PGE₁ applied after HCG, could evoke a new increased release of cAMP. HCG applied after PGE₁ also gave rise to a renewed response in accordance with the experiments with double PGE₁ pulses. In these double pulse experiments, the response to the second challenge was always considerably suppressed in relation to the first.     

Immunogenicity and toxicity of lipopolysaccharide from Francisella tularensis LVS

Abstract Lipopolysaccharide (LPS) from the live vaccine strain of Francisella tularensis ( F . tularensis LVS) was isolated and purified. The LPS did not stimulate lymphocytes from previously tularaemia-vaccinated individuals or lymphocytes from nonprimed individuals. However, serum antibodies from tularaemia vaccines reacted with the LPS whereas virtually no reactivity was found with antibodies from individuals not exposed to F. tularensis LVS. Antibodies of immunoglobulin class M displayed the antibody reactivity predominantly. The LPS failed to induce the mononuclear cell-derived cytokine interleukin-1 and only low levels of tumour necrosis factor were detected. Furthermore, no LPS endotoxin properties were found in galactosamine-treated mice or in the Limulus amoebocyte lysate assay. From these results it can be concluded that F. tularensis LVS possesses a lipopolysaccharide-like molecule, which does not exhibit properties of a classical endotoxin.     

Effects of low temperature on contraction in papillary muscles from rabbit, rat, and hedgehog

During hibernation the body temperature may fall to only a few degrees above 0 degree C. The heart of the hedgehog continues to function whereas the hearts of nonhibernating mammals stop beating. The present study was performed to investigate and compare the mechanical responses to hypothermia in rabbits, rats, and hedgehogs. Isometric force was recorded from papillary muscles mounted in an organ bath and effects of hypothermia on the mechanical restitution curve were also compared. A reduction of bath temperature from 35 degrees C caused an increase in peak developed force. Maximum force was seen at 20 degrees C in the rabbit, 15 degrees C in the rat, and 10 degrees C in the hedgehog preparations. In all the species there was a similar prolongation of time to peak force and of time from peak to half-relaxation as temperature was lowered. An increase in resting force and after-contractions were recorded in the rabbit and rat muscles at temperatures below 15 and 10 degrees C, respectively. The rabbit and rat preparations became inexcitable at temperatures below 10 and 5 degrees C, respectively. The hedgehog papillary muscle, on the other hand, still contracted at 0 degree C and did not show increased resting force nor after-contractions. The results are consistent with the hypothesis that there is a calcium overload in cardiac cells from rabbit and rat at low temperatures but there is no calcium overload in the hedgehog muscle during hypothermia.     

New assay for uronosyl 5-epimerases

Simple assays have been developed for the two uronosyl 5-epimerases which participate in the biosynthesis of heparin and dermatan sulfate (heparosan N-sulfate D-glucuronosyl 5-epimerase and chondroitin D-glucuronosyl 5-epimerase, respectively). Following previously published procedures, substrates labeled with tritium in the C-5 positions of the D-glucuronosyl and L-iduronosyl residues were prepared enzymatically by incubation of O-desulfated heparin and dermatan with 3H2O and crude epimerase preparations from bovine liver and human skin fibroblasts, respectively. In the new assays, 3H2O generated from these substrates during the epimerase reactions was quantitated by the method of Pollard et al. (Anal. Biochem. (1981) 110, 424-430). In this procedure, 3H2O in the aqueous reaction mixture is extracted into a toluene-based organic phase containing 25% isoamyl alcohol, while the polysaccharide substrate remains in the aqueous phase and does not generate scintillations. This procedure is much simpler than that used previously which involves distillation of each reaction mixture and quantitation of the radioactivity in the distillate. The new assays have been validated by the demonstration that conditions of linearity with time and enzyme concentration can be established for both epimerase reactions. Assays of this type should be useful in the study of any enzymatic reaction where 3H2O is formed from a 3H-labeled substrate and the unreacted substrate is not appreciably soluble in the organic phase.     

The function of carotenoids during chloroplast development. V. Correlation between carotenoid content, ultrastructure and chlorophyll b to chlorophyll a ratio

The ultrastructural effect of carotenoid deficiency in wheat ( Triticum aestivum L. ) was studied after adding the herbicide SAN-9789 to the growth medium. The presence of SAN-9789 (28 mg I^-1) resulted in an almost complete absence of carotenoids. For plants grown in darkness the lack of carotenoids was accompanied by a reduction in partitions between primary thylakoids as well as a change in appearance of the plastoglobuli from small and black (osmiophilic) to large and greyish white (less osmiophilic). When plants were grown in weak red light (16 mW m^-2), the presence of SAN-9789 also resulted in an almost complete absence of grana, a decrease in the ratio of chlorophyll b /chlorophyll a from 0.25 to 0.1, and an almost complete absence of prolamellar bodies. The greatest differences in carotenoid content, in amount of grana, in chlorophyll b /chlorophyll a ratio, and in number of prolamellar bodies, all occurred between 0.28 and 2.8 mg I^-1 of SAN-9789. The change in appearance of plastoglobuli occurred at a lower SAN-9789 concentration, between 0.028 and 0.28 mg I^-1. The ultrastructural responses to the SAN-9789 treatment could be related to the effect on the carotenoid synthesis in different ways. The disappearance of thylakoid partitions was connected to a structural role of carotenoids, while the disappearance of the prolamellar bodies was dependent on the photoprotective role of carotenoids. The change in shape and size of plastoglobuli was not correlated to the presence of carotenoids. However, a connection to the accumulation of the carotenoid precursors is still possible.     

Data and theory for a revised chiasma map of man

Summary Chiasma maps appropriate to chiasma conservation and terminalization are derived from new data on chiasma distributions and high-resolution banding. Here detailed data for arms with and without a terminal chiasma and improved estimates of mapping parameters are given. Utility of chiasma maps is limited by uncertainty about the nature and extent of chiasma movement. These results are being integrated with genetic data and physical assignments.This work was supported by grant GM 17173 from the U.S. National Institutes of Health. We are grateful to M. Hulten for unpublished data