Transfer of reducing equivalents into mitochondria by the interconversions of proline and Δ1-pyrroline-5-carboxylate

Direct evidence is presented for a proline cycle using a cell-free experimental system which sequentially transfers ³H from [1-³H]glucose to NADP⁺ to Δ¹-pyrroline-5-carboxylate and yields [³H]proline. The formation of [³H]proline depends on the presence of NADP, Δ¹-pyrroline-5-carboxylate, and the enzymes glucose-6-phosphate dehydrogenase and Δ¹-pyrroline-5-carboxylate reductase. The production of [³H]proline from unlabeled proline in the presence of mitochondria provides direct evidence for one complete turn of a proline cycle which transfers reducing equivalents produced by glucose oxidation in the pentose pathway into mitochondria. In this cycle, proline is oxidized to Δ¹-pyrroline-5-carboxylate by mitochondrial proline oxidase. Δ¹-pyrroline-5-carboxylate is released from mitochondria and is recycled back to proline by Δ¹-pyrroline-5-carboxylate reductase with concomitant oxidation of NADPH. At the maximal rate observed, 60% of Δ¹-pyrroline-5-carboxylate produced is recycled back to proline. This cycle provides a mechanism for transferring reducing equivalents from NADPH into mitochondria and is linked to glucose oxidation in the pentose pathway by NADPH turnover.     

Coprophagy in larval Culiseta bergrothi (Diptera: Culicidae)

Two experimental groups of Culiseta bergrothi Edw. larvae were kept under laboratory conditions, but in water from the breeding locality. The ‘donors’ were fed on a suspension of charcoal powder and baker's yeast; the ‘receivers’ had access to the faecal pellets of the donors. After 1.5 hours the gut of almost all receivers was more or less filled with charcoal particles. The possible consequences of the added yeast suspension to food choice and feeding behaviour are discussed.     

Lipid composition and food quality of some freshwater phytoplankton for cladoceran zooplankters

The nutritional value of several planktonic algae was testedby means of feeding trials with three cladoceran zooplankters.The algae were monocultures and included two blue-greens, fourgreens and four flagellates with a size range of 5–48µm. The specific growth rates of the zooplankters werechosen as the measure of the nutritional value of the algae.The three cladocerans showed large differences in growth ratein the different algae, but the two cryptomonads were withoutdoubt best suited as food for all. The fatty acid compositionfor the cryptomonads were different from the other algae. Theycontained high percentages of the polyunsaturated fatty acids20:5æ3 (EPA) and 22:6æ3 (DHA), which also are commonin fish. It is suggested that the lipid composition is a probablefactor determining the nutritional quality of the algae.     

Thidiazuron-induced adventitious shoot regeneration of sweetpotato (Ipomoea batatas)

Adventitious shoots of sweetpotato (Ipomoea batatas L. Lam.) were produced in vitro using a two-stage culture method. Petiole explants were incubated on Murashige and Skoog (MS) medium supplemented with 2,4-dichlorophenoxy acetic acid (0.2 mg·liter^−1) for 3 d, and transferred to MS medium with thidiazuron (0 to 0.4 mg·liter^−1). Shoot regeneration was observed in most explants (78.2%) of genotype PI 318846-3 within 28 days when cultured on thidiazuron at 0.2 mg·liter^−1. Histological studies of cultured petiole explants showed meristematic activity within cells of vascular bundles and throughout the ground tissue. Explants isolated from apical leaves exhibited higher shoot regeneration frequency than those isolated from the basal portion of the shoot. Leaf lamina explants exhibited lower frequency of regeneration than petiole explants. In contrast to thidiazuron, the use of zeatin riboside, and kinetin resulted in a lower frequency of shoot regeneration although more sweetpotato genotypes could be regenerated using either of these two cytokinins. The sweetpotato plants regenerated using thidiazuron grew vigorously and rooted easily when transferred to the greenhouse.     

Paraveinal mesophyll: Review and survey of the subtribeErythrininae (Phaseoleae,Papilionoideae, Leguminosae)

Paraveinal mesophyll (PVM) is a distinctive anatomical feature of the leaf mesophyll of some plant taxa that may represent a specialized physiological compartment. A comprehensive review of the 42 published references that mention PVM or similar cell layers and a survey of 121 of the 272 species of all nine genera of thePhaseoleae subtribeErythrininae demonstrate that PVM is nearly exclusively found inLeguminosae. InLeguminosae, PVM is either rare or absent in subfamilyCaesalpinioideae, uncommon inMimosoideae, and extensively distributed amongPapilionoideae. In subtribeErythrininae, PVM is ubiquitous inErythrina, and occurs in four other genera. ThreeErythrininae genera (Apios, Mucuna, andCochlianthus) lack PVM. Unique chloroplast-poor, enlarged conical cells (pellucid palisade idioblasts) occur in 80 species ofErythrina but not in any other genus ofErythrininae.     

Antihypertensive Pharmacology

Although drug treatment of hypertension is associated with improved survival and decreased vascular complications, drug compliance is a major problem in the control of hypertension. All antihypertensive medications are associated with side effects; thus, it is a physician''s responsibility to explain to each patient the side effects of the drugs he prescribes to treat hypertension, and to instill in the patient a sense of necessity for the treatment of hypertension. The choice of antihypertensive drug should be made based on each patient''s lifestyle, overall health and ability to tolerate the drug. Ideally, the antihypertensive regimen should be simple, effective, convenient to take and have very few side effects.     

Leukotriene A: stereochemistry and enzymatic conversion to leukotriene B

Leukotriene A was assigned the structure 5(S)-$\text{trans}$-5,6-oxido-7,9-$\text{trans}\text{-11,14-}\text{cis}$-eicosatetraenoic acid by the enzymatic conversion of a synthetic product of known stereochemistry into the naturally occurring isomer of 5(S),12(R)-dihydroxy-6,8,10,14-eicosatetraenoic acid in human polymorphonuclear leukocytes.     

BRAIN TISSUE AND PLASMA ASSAY OF L-DOPA AND α-METHYLDOPA METABOLITES BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION

Using reverse phase high-performance liquid chromatography and electrochemical detection with mobile phases composed of simple acids, we have developed an assay technique to measure multiple catecholamines and their catechol metabolites in plasma or brain tissue with sensitivity to the picomole level. Ion-pairing chromatography with nitric or trichloroacetic acid as the mobile phase permits separation and quantitation of norepinephrine, α-methylnorepinephrine, epinephrine, dopamine, α-methyldopamine, l -DOPA, α-methyldopa, carbidopa, and DOPAC. Alumina extraction selectively isolates catechols which are then separated on a reverse-phase column and measured by a commercially available electrochemical detector. This method has been applied to measurement of L-DOPA metabolites in patients with Parkinson's disease treated with L-DOPA and carbidopa and to measurement of catecholamines in rat hypothalamus in the course of studies on L-DOPA and α-methyldopa metabolism. Dihydroxybenzylamine is added as an internal standard and standard curves are linear over two orders of magnitude in concentration with coefficients of variation averaging 3.1%. Quantitation is routinely done to 20 pmol with absolute sensitivity possible to 0.5 pmol.     

Empirical choice of sampling procedures for optimal research design in the longitudinal study of primate behavior

A method is suggested to evaluate on an empirical basis sampling plans for the longitudinal study of primate behavior in those very common situations in which the mathematical structure of behavior is unknown. The method is based on a randomization procedure applied to a pilot sample of the behavior organized so that cost of implementation of a sampling plan can be evaluated vis á vis the sampling error intrinsic to the plan.     

Drug-Induced Changes in Blood Pressure Lead to Changes in Extracellular Concentrations of Epinephrine, Dihydroxyphenylacetic Acid, and 5-Hydroxyindoleacetic Acid in the Rostral Ventrolateral Medulla of the Rat

Neurochemical changes in the extracellular fluid of the rostral ventrolateral medulla (RVLM) were produced by changes in arterial blood pressure. Blood pressure was raised or lowered with systemic infusions of phenylephrine or nitroprusside and neurochemicals were recovered from RVLM by in vivo microdialysis. A dialysis probe 300 microns in diameter and 500 microns in length was stereotaxically implanted in the RVLM of the urethane-anesthetized rat. Sterile physiological Ringer's solution was perfused at a rate of 1.5 microliter/min. The perfusate was collected under ice-cold conditions every 15 min for the assay of epinephrine, dihydroxyphenylacetic acid (DOPAC), 5-hydroxyindoleacetic acid (5-HIAA), ascorbic acid, and uric acid. After stable baseline neurochemical concentrations were achieved, animals were infused with phenylephrine or nitroprusside intravenously to raise or lower the blood pressure. Increasing blood pressure 50 mm Hg above the baseline value by phenylephrine led to a significant reduction in heart rate and a reduction in extracellular epinephrine and DOPAC concentrations. The 5-HIAA concentration was increased during the hypertensive drug infusion. There were no changes in the concentrations of ascorbic acid or uric acid. Hypotension produced by nitroprusside (-20 mm Hg) led to neurochemical changes which were the reciprocal of those seen during hypertension. During hypotension, heart rate increased as did the extracellular fluid epinephrine concentration. The 5-HIAA concentration fell with hypotension and remained depressed following the nitroprusside infusion. Ascorbic acid and uric acid concentrations did not change during hypotension but ascorbic acid did increase after the nitroprusside infusion stopped. These data provide direct evidence that epinephrine release in RVLM is linked to changes in systemic blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)