Central neural peptides and catecholamines in spontaneous and DOCA/salt hypertension

Hypothalamic and neurophypophyseal levels of catecholamines and peptides were measured in spontaneous and deoxycorticosterone (DOCA)/salt hypertension. Catecholamines, norepinephrine, epinephrine and dopamine were measured by electrochemical detection while the peptides, vasopressin, oxytocin, luteinizing hormone-releasing hormone (LHRH), the enkephalins and somatostatin (SRIF) were measured by radioimmunoassay. Blood pressure was significantly elevated in both groups as compared to their controls. Marked changes in central neural peptides were observed in the SHR, while no differences were seen in DOCA/salt hypertension. Hypothalamic vasopressin, oxytocin, LHRH and SRIF were significantly decreased. In the posterior pituitary, enkephalins were increased twofold in the SHR. With regard to catecholamines, there was no change in hypothalamic content. However, a dramatic decrease in neurohypophyseal dopamine was observed in SHR. Plasma levels of vasopressin were significantly elevated in both types of hypertension while oxytocin was increased only in the DOCA/salt model. These result show that (1) a wide spectrum of neuroendocrine changes are associated with genetic hypertension, (2) there are CNS differences between DOCA/salt and spontaneous hypertension, and (3) central aminergic changes may be involved in th neuroendocrine alterations seen in the SHR.     

A redescription of the Middle Cambrian wormAmiskwia sagittiformis Walcott from the Burgess Shale of British Columbia

Amiskwia sagittiformis Walcott is redescribed on the basis of the five available specimens. The dorsoventrally compressed body consists of a head bearing a pair of prominent tentacles and a trunk with lateral and caudal fins. A gut with subterminal openings, cerebral ganglia, nerve cords, blood vessels and muscles have been identified with varying degrees of confidence. An active pelagic mode of life is considered probable. The rejection by earlier workers of this worm from the arrow-worms (Chaetognatha) is confirmed, but their identification of it as a nemertean (Nemertea) cannot be supported owing to the absence of critical data. The systematic position ofA. sagittiformis remains unresolved.     

6-Hydroxydopamine produces a weight increase in toads

A large increase in body weight occurred after injection of 6-hydroxydopamine (6-OHDA, 100 mg kg-1) into the iliac lymph sac of toads. The body weight increase was apparently due to retention of fluid and only occurred when toads could not avoid contact of their ventral skin with water. Lower doses of 6-OHDA (25 or 50 mg kg-1) did not cause a weight increase although they were sufficient to eliminate fluorescence from peripheral adrenergic nerves. A peripheral injection of 6-OHDA did not affect the appearance of central aminergic nerves. Removal of the pituitary and median eminence did not affect the weight increase. Although the primary action of 6-OHDA in upsetting water balance in toads has not been revealed by this study, it is clearly not related to the chemical sympathectomy of adrenergic nerves.     

Secretion of trans-zeatin by Agrobacterium tumefaciens: A function determined by the nopaline Ti plasmid

Production of the plant cytokinin, trans-zeatin, by a number of strains of Agrobacterium tumefaciens was measured by a combination of traceenrichment, HPLC and radioimmunoassay and confirmed by mass spectrometry. Secretion of trans-zeatin into a culture medium is a constitutive function of those strains which harbor a nopaline Ti plasmid. Strains cured of the nopaline Ti plasmid and those which harbor octopine or agropine plasmids are non-producers. Reacquisition of nopaline plasmids by cured strains restores production.     

Genetic mapping of new RFLPs at Xq27-q28.

The development of the human gene map in the region of the fragile X mutation (FRAXA) at Xq27 has been hampered by a lack of closely linked polymorphic loci. The polymorphic loci DXS369 (detected by probe RN1), DXS296 (VK21A, VK21C), and DXS304 (U6.2) have recently been mapped to within 5 cM of FRAXA. The order of loci near FRAXA has been defined on the basis of physical mapping studies as cen-F9-DXS105-DXS98-DXS369-DXS297-FRAXA-++ +DXS296-IDS-DXS304-DXS52-qter. The probe VK23B detected HindIII and XmnI restriction fragment length polymorphisms (RFLPs) at DXS297 with heterozygote frequencies of 0.34 and 0.49, respectively. An IDS cDNA probe, pc2S15, detected StuI and TaqI RFLPs at IDS with heterozygote frequencies of 0.50 and 0.08, respectively. Multipoint linkage analysis of these polymorphic loci in normal pedigrees indicated that the locus order was F9-(DXS105, DXS98)-(DXS369, DXS297)-(DXS293,IDS)-DXS304-DXS52. The recombination fractions between adjacent loci were F9-(0.058)-DXS105-(0.039)-DXS98-(0.123)-DXS369-(0.00)- DXS297-(0.057)-DXS296- (0.00)-IDS-(0.012)-DXS304-(0.120)-DXS52. This genetic map will provide the basis for further linkage studies of both the fragile X syndrome and other disorders mapped to Xq27-q28.     

The accumulation and intracellular compartmentation of cadmium,lead, zinc and calcium in two earthworm species (Dendrobaena rubida and Lumbricus rubellus) living in highly contaminated soil

Summary The earthworm Lumbricus rubellus contained more Ca and Zn, and less Pb and Cd, than Dendrobaena rubida living in the same contaminated disused-mine soil. Differences in the kinetics of Ca turnover may account for some of the inter-specific differences in heavy metal burdens, although the calciferous glands do not seem to be directly involved in heavy metal excretion. A comparison of the present findings with published data indicated that the concentration of soil Ca and the bioavailability of heavy metals, both factors being allied to soil pH, are important exogenous determinants of heavy metal accumulation by different earthworm populations. Electron microprobe X-ray analysis of air-dried smears of chloragogenous tissue showed that the metals were fairly specifically compartmentalized into two distinct organelles in both worms: Ca, Pb and Zn were found (associated with P) in the chloragosomes; Cd was found (with S and probably in stoichiometric association) in a more electron-lucent vesicular component, designated the cadmosome, but which may be identical with the debris vesicles which are characteristic inclusions in conventionally-fixed chloragocytes. The in vivo incorporation of Pb by the chloragosomes of D. rubida was accompanied by the loss of Ca, Zn and P.     

Fast atom bombardment: A new mass spectrometric method for peptide sequence analysis

We have studied a selection of peptides using a new mass spectrometric ionisation technique - fast atom bombardment (FAB). We define the fragmentation pathways observed and comment on the utility in sequence analysis. A simple acetylation experiment is shown to aid rapid sequence assignment.     

Individual variation of nucleoside triphosphate pyrophosphohydrolase activity in human erythrocytes,granulocytes, lymphocytes,and platelets

Analysis of the nucleoside triphosphate pyrophosphohydrolase specific activity of red cells obtained from a random Caucasian population indicated at least two subclasses. The specific activity of 18% of the population ranged from undetectable activity to 27.5 nmol ITP cleaved/20 min/mg hemoglobin. The remainder of the population had higher activity, 27.5–125 nmoles ITP cleaved/20 min/mg hemoglobin. The variation of NTPH activity evident in the red cells of an individual is reflected in granulocytes, lymphocytes, and platelets of that individual. Erythrocyte activity ranges from 0.7 to 21 units (nmol of ITP cleaved in 20 min)/10⁷ cells, granulocytes have 17–201 units/10⁷ cells, lymphocytes have 91–462 units/10⁷ cells, and platelets have 1.1–7.1 units/10⁷ platelets. These cell differences are discussed with respect to the hypothesis that NTPH prevents incorporation of ITP or dITP into nucleic acids.This work was supported by funds allocated by the Agricultural Experiment Station, Michigan State University. Michigan Agricultural Experiment Station Journal No. 8727.