Unterschiede im revier- und sexualverhalten endemisch-anatolischer zahnkarpfen (pisces,cyprinodontidae)

The endemic Anatolian cyprinodonts Aphanius chantrei, A. (Kosswigichtys) asquamatus, and A. anatoliae show definite interspecific differences in their territorial and sexual behaviour under laboratory conditions. Intraspecific differences were found in the nine populations of A. anatoliae investigated.A. chantrei and Kosswigichthys show almost the same territorial behaviour. In A. anatoliae territoriality is found in three populations; the remaining six populations show no territoriality.The sexual behaviour consists of visual display elements and of elements which enable the fish to keep close contact without actually touching each other. The sequence of elements can be variable. Only two populations of A. anatoliae have retained display elements; the remaining seven populations have lost all of them.A correlation is discussed between biotope conditions and sexual behaviour. Display and territorial behaviour may have become superfluous in extreme, sulphate-containing habitats, where a lack of flora has led to a lack of spawning sites. Under changing breeding conditions the newly evolved element with fish staying close together (male underneath the female) may have replaced the former display elements.     

Ein einfaches Mikrokolorimeter

Ohne Zusammenfassung     

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.     

Relationships among the streptothricin resistance transposons Tn1825 and Tn1826 and the trimethoprim resistance transposon Tn7

The streptothricin resistance transposons Tn1825 and Tn1826 are closely related, based on physical and genetic characteristics, to the trimethoprim resistance transposon Tn7. These transposons may be considered to be members of a transposon family sharing in common the transposition functions and a basic streptomycin/spectinomycin resistance determinant but differing from one another with respect to particular additional resistance genes inserted to the left of the aadA gene.     

Calculation of leaf photosynthetic parameters from light-response curves for ecophysiological applications

Measurement of the light response of photosynthetic CO₂ uptake is often used as an implement in ecophysiological studies. A method is described to calculate photosynthetic parameters, such as the maximum rate of whole electron transport and dissimilative respiration in the light, from the light response of CO₂ uptake. Examples of the light-response curves of flag leaves and ears of wheat (Triticum aestivum cv. ARKAS) are shown.Abbreviations and symbols A net photosynthesis rate - D ¹ rate of dissimilative respiration occurring in the light - f loss factor - I incident PPFD - I effective absorbed PPFD - J rate of whole electron transport - J _m maximum rate of whole electron transport - p ^c intercellular CO₂ partial pressure - PPFD photosynthetic photon flux density - q effectivity factor for the use of light (electrons/quanta) - absorption coefficient - I ^* CO₂ compensation point in the absence of dissimilative respiration (bar) - II conversion factor for calculation of CO₂ uptake from the rate of whole electron transport - convexity factor Gas-exchange rates relate to the projective area and are given in mol·m^-2·s^-1. Electron-transport rates are given in mol electrons·m^-2·s^-1; PPFD is given in mol quanta·m^-2·s^-1.     

Restriction analysis of lambda EMBL3 background recombinants: occurrence of lambda phages carrying a head to tail oriented left arm DNA sequence

Summary Eight representative recombinant background clones of λEMBL3 were analysed usingKpnI,BamHI,SalI,EcoRI andHindIII digestion. We found that λEMBL3 carries its own left arm in theBamHI cloning site. In this way, recombinant molecules were found to be generated which can grow onEscherichia coli strain NM539. In all cases analysed, the left arm DNA was inserted in a head to tail orientation. Seven clones carried a restoredBamHI site at thecos site-BamHI site connection. In the region where the inserted left arm and the right arm were ligated,BamHI cloning produces a large palindromic sequence consisting of two polylinkers. ThisBamHI site was incompletely cleaved in all cases analysed. We assume that a part of the λ DNA molecule in this region shows a cruciform structure prohibiting recognition or cleavage of this site by restriction endonucleaseBamHI.     

Self-association of nucleotides

The self-association of nucleosides decreases within the series adenosine>guanosine>inosine>cytidine ≈uridine. The same trend is observed for the corresponding nucleotides, though less pronounced, as the charge effect governs series like adenosine ? AMP^2?>ADP^3??ATP^4?. Protonation of adenosine considerably reduces its self-stacking tendency: this is different with ATP^4?, where a maximum is reached for H₂(ATP)^2? caused by additional ionic interactions in the [H₂(ATP)]₂ ^4? dimer. Metal ion coordination may promote self-association, e.g., of ATP^4? via (mainly) charge neutralization (Mg²⁺) and the formation of intermolecular bridges in dimeric stacks (Zn²⁺, Cd²⁺). These results allow definition of conditions with negligible self-association and thus the determination of the stability and structure of monomeric nucleotide complexes in aqueous solution, e.g., quantification of macrochelate formation in M(ATP)^2? complexes. Some biological implications of the results are indicated.     

Rhizobacteria of Cotton and Their Repression of Seedling Disease Pathogens

During the 1983 field season, the rhizobacteria (including organisms from rhizosphere soil and the root rhizoplane) of cotton plants at one location in Mississippi were inventoried at different plant growth stages. Isolates (1,000) were identified to the genus level and characterized for repression of Pythium ultimum and Rhizoctonia solani. Cotton seedlings were initially colonized by bacteria of many different genera, and populations quickly reached 10⁸ CFU/g of root tissue. As the season progressed, the bacterial populations declined as root mass increased and the roots became more woodlike in consistency. Fluorescent pseudomonads were the most numerous gram-negative rhizobacterial isolates of those that were randomly collected and identified, and they provided the largest number of isolates with fungal repressive activity. Several other gram-negative bacterial genera were recovered throughout the growing season, and some gram-positive bacteria were also isolated routinely, but at lower numbers. There was no correlation between the proportion of rhizobacterial isolates that possessed fungal repressive activity and the plant growth stage from which the isolates were obtained. Approximately twice as many bacterial isolates demonstrated fungal repression in the agar assay compared with the inplanta assay, and isolates were found more frequently with fungal repressive activity against P. ultimum than against R. solai.     

Protein kinase C inhibition by calmodulin and its fragments

Inhibition of protein kinase C (PKC) by calmodulin is investigated and we describe the localization of inhibitory sequences within the calmodulin molecule. We present evidence that calmodulin inhibits PKC through an inhibition of the activation of PKC associated with lipid membranes: Binding of PKC to lipid vesicles is not affected, but activation is abolished. The potent calmodulin antagonist R24571 (calmidazol) did not affect the inhibition of PKC by calmodulin at concentrations up to 10^–5 M. Two tryptic fragments of calmodulin were isolated which inhibited PKC. They were only slightly less potent than intact calmodulin with an IC₅₀ of 6 µ M compared to 1 µ M of intact calmodulin. They were identified as Ser³⁸-Arg⁷⁴ and His¹⁰⁷-Lys¹⁴⁸. Each of the inhibiting fragments contains an intact Ca²⁺-binding domain with complete helix-loop-helix structure (EF hand). Other calmodulin peptides showed only weak inhibitory activity. Both fragments did not stimulate cAMP phosphodiesterase even at concentrations 100-fold higher than the calmodulin concentration needed for maximal stimulation. None of the fragments acted as a calmodulin antagonist.