The influence of zinc and sulphur deficiency on oil-filling in peanut (Arachis hypogaea L.) kernels

In the developing peanut (Arachis hypogaea L.) kernels, the period between 15 and 35 days after podding (DAP) was identified as the active period of oil-filling. The period of active oil-filling was associated with a decrease in the starch, soluble sugars and proteins so as to make available the energy and carbon skeleton for the synthesis of oil. The oil content in the mature kernels decreased by 11, 12 and 25 per cent with Zn, S and Zn+S deficiency, respectively. In addition, proteins and starch content decreased significantly while that of soluble sugars increased slightly. The activity of malate dehydrogenase and glucose-6-phosphate dehydrogenase also decreased due to Zn as well as S deficiency. The deficiency treatments resulted in a decrease in phospholipids, free fatty acids and triacylglycerols in mature kernels. Further the proportion of 16∶0 and 18∶2 decreased while that of 18∶1 increased in developing kernels.     

The analysis of planktonic rotifer populations: A plea for long-term investigations

Short-term species succession, and long-term community development, of planktonic rotifer populations of the temperate zone and factors influencing species' abundance (ie., physical and chemical limitations, food and exploitative competition, mechanical interference competition, predation, parasitism) are described and discussed. The long-term development of plankton communities in three European lakes is described and the major events are discussed in relation to ecological interactions. Frequently, the shortcomings of our knowledge about population ecology and ecophysiology of rotifers prevent explanations of short-term and, especially, of long-term developments of these plankton organisms. The need for qualitative and quantitative observations in the field and in the laboratory over long periods becomes obvious.     

Effects of membrane physical parameters on hematoporphyrin-derivative binding to liposomes: A spectroscopic study

Summary Physical parameters of membrane bilayers were studied for their effect on the binding of hematoporphyrin derivative (Hpd), which is used as a sensitizer in photodynamic therapy of cancerous tissues. The purpose of this study was to clarify which parameters were relevant, under physiological conditions, to the selectivity of Hpd binding to cancer cells. Fluorescence spectroscopy was used to measure the relative partitioning of the dye between the lipid and aqueous media. Increasing the microviscosity of the liposomes' membranes by various bilayer additives results in a strong reduction of Hpd binding, to an extent independent of the specific additive. The effect of temperature near the physiological value as well as the effect of cross membrane potential are small. Surface potential does not affect the binding constant, indicating that the binding species does not carry a net electric charge.     

Sequence instability in the long terminal repeats of avian spleen necrosis virus and reticuloendotheliosis virus

Summary Sequence divergence between the 3 long terminal repeats (LTR) of avian reticuloendotheliosis virus (REV), deletion variant proviral clone 2-20-4, and spleen necrosis virus (SNV)—proviral clones 14-44, 60, and 70—was found to involve two classes of base substitutions: low-frequency interspersed and high-frequency clustered substitutions. Clones 2-20-4 and 14-44 have diverged 4.4% owing to low-frequency substitutions. In contrast, two high-frequency substitution segments have diverged by 30% and 29%, respectively. Clustered substitutions appear to be located either within or next to tandem repeats, suggesting their introduction concomitant with sequence deletions and duplications commonly associated with such repeats. A new 19-bp tandem repeat is found in clone 2-20-4. Its sequence could have evolved from the 26-bp repeats found in the SNV clones.     

Effects of α2-Adrenergic Agonists and Antagonists on Photoreceptor Membrane Currents

Type B photoreceptors of the nudibranch mollusc Hermissenda crassicornis receive excitatory synaptic potentials (EPSPs) whose frequency is controlled by potential changes of a neighboring cell known as the S optic ganglion cell which is thought to be electrically coupled to the presynaptic source of these EPSPs, the E optic ganglion cell. The frequency of the EPSPs increases when a conditioned stimulus (light) is paired with an unconditioned stimulus (rotation) during acquisition of a Pavlovian conditioned response. The results of the present study are consistent with an adrenergic origin for these EPSPs. Noradrenergic agonists (greater than 100 microM), norepinephrine and clonidine, only slightly depolarize the type B cell but clearly prolong its depolarizing response to light. Serotonin, by contrast, causes hyperpolarization of the type B cell's resting potential as well as after a light step. Clonidine reduces voltage-dependent outward K+ currents (IA, an early current, ICa2+-K+, a late Ca2+-dependent current) that control the type B cell's excitability (and thus its light response and membrane potential). These effects of clonidine are reduced or blocked by the alpha 2-receptor antagonist, yohimbine (0.5 microM), but not the alpha 1-blocker, prazosin. The same yohimbine concentration also blocked depolarizing synaptic excitation of the type B cell in response to depolarization of a simultaneously impaled S optic ganglion cell. Histochemical techniques (both the glyoxylic acid method of de la Torre and Surgeon and the formaldehyde-induced fluorescence or Falck-Hillarp method) demonstrated the presence of a biogenic amine(s) within a single neuron in each optic ganglion as well as three or four cells within the vicinity of previously identified visual interneurons. No serotonergic neurons were found within the optic ganglion or in proximity to visual interneurons. A clonidine-like synaptic effect on type B cells, therefore, could amplify conditioning-specific changes of membrane currents by increasing type B depolarization and possibly, as well, by elevating intracellular second messengers.     

Repeated floristical observations on islets in the Aegean

Repeated observations are made on species and numbers of individuals in some islets. The changes after 14 years are reported for 11 islets. They include several extinctions and invasions. Great changes in numbers of individuals were found, especially for many of the annuals, in some of them as great as between 0–10 and over 10 000 individuals. The greatest constancy was found in a few dominant and subdominant perennials.Dedicated to Prof.K. H. Rechinger on the occasion of his 80th birthday.     

Revision of the plant geographical territories of Israel and Sinai

The phytogeographical territories of Israel and Sinai are revised using a large mass of species distribution data. With the help of chorotype frequencies for 25 km² individual squares in Israel, territories were defined on the basis of the first two most frequent chorotypes. The similarity of boundaries in the resulting phytogeographical map with a physiognomic map suggests that the latter may be used in preliminary stages of the preparation of plant geographical maps.     

Delimitation and classification ofBromus fasciculatus (Poaceae)

The syntypes ofBromus madritensis var.delilei Boiss. comprise two different elements: specimens ofB. haussknechtii Boiss. and ofB. fasciculatus C. Presl s.l. By its lectotypification and on the basis of new morphological characters, the validation ofB. fasciculatus subsp.delilei (Boiss.)H. Scholz 1971 was substantiated. This subspecies represents the eastern marginal segregate of the south-Mediterranean species.B. fasciculatus var.alexandrinus Thell. is a minor variant of the typical subspecies.Dedicated to Prof.K. H. Rechinger on the occasion of his 80th birthday.     

Sex determination of fetal and neonate skeletons by means of discriminant analysis

Facing the requirements of refined paleodemographical analyses, the access to the early ontogenetic sex ratio of skeletal populations is an important feature. Using raw data provided byFazekas & Kosa (1978) for a sample of known sex, discriminant functions are derived from hip and thigh bone dimensions that allow an almost unbiased classification of more than 70% of fetal and neonate individuals.     

Succinate metabolism related to lipid synthesis in the housefly Musca domestica L

The metabolism of succinate was examined in the housefly Musca domestica L. The labeled carbons from [2,3-¹⁴C]succinate were readily incorporated into cuticular hydrocarbon and internal lipid, whereas radioactivity from [1,4-¹⁴C]succinate was not incorporated into either fraction. Examination of the incorporation of [2,3-¹⁴C]succinate, [1-¹⁴C]acetate, and [U-¹⁴C]proline into hydrocarbon by radio-gas-liquid chromatography showed that each substrate gave a similar labeling pattern, which suggested that succinate and proline were converted to acetyl-CoA prior to incorporation into hydrocarbons. Carbon-13 nuclear magnetic resonance showed that the labeled carbons from [2,3-¹³C]succinate enriched carbons 1, 2, and 3 of hydrocarbons with carbon-carbon coupling showing that carbons 2 and 3 of succinate were incorporated as an intact unit. Radio-high-performance liquid chromatographic analysis of [2,3-¹⁴C]succinate metabolism by mitochondrial preparations showed that in addition to labeling fumarate, malate, and citrate, considerable radioactivity was also present in the acetate fraction. The data show that succinate was not converted to methylmalonate and did not label hydrocarbon via a methylmalonyl derivative. Malic enzyme was assayed in sonicated mitochondria prepared from the abdomens and thoraces of 1- and 4-day-old insects; higher activity was obtained with NAD⁺ in mitochondria prepared from thoraces, whereas NADP⁺ gave higher activity with abdomen preparations. These data document the metabolism of succinate to acetyl-CoA and not to a methylmalonyl unit prior to incorporation into lipid in the housefly and establish the role of the malic enzyme in this process.