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     

High sequence similarity within ras exons 1 and 2 in different mammalian species and phylogenetic divergence of the ras gene family

We have determined the canine and feline N-, K-, and H-ras gene sequences from position +23 to +270 covering exons I and II which contain the mutational hot spot codons 12, 13, and 61. The results were used to assess the degree of similarity between ras gene DNA regions containing the critical domains affected in neoplastic disorders in different mammalian species. The comparative analyses performed included human, canine, feline, murine, rattine, and, whenever possible, bovine, leporine (rabbit), porcelline (guinea pig), and mesocricetine (hamster) ras gene sequences within the region of interest. Comparison of feline and canine nucleotide sequences with the corresponding regions in human DNA revealed a sequence similarity greater than 85% to the human sequence. Contemporaneous analysis of previously published ras DNA sequences from other mammalian species showed a similar degree of homology to human DNA. Most nucleotide differences observed represented synonymous changes without effect on the amino acid sequence of the respective proteins. For assessment of the phylogenetic evolution of ras gene family, a maximum parsimony dendrogram based on multiple sequence alignment of the common region of exons I and II in the N-, K-, and H-ras genes was constructed. Interestingly, a higher substitution rate among the H-ras genes became apparent, indicating accelerated sequence evolution within this particular clade. The most parsimonious tree clearly shows that the duplications giving rise to the three ras genes must have occurred before the mammalian radiation. Received: 23 July 1997 / Accepted: 30 October 1997     

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.     

Nucleolus organizer regions and heterochromatin in the zebu (Bos indicus L.)

Summary Ag-NOR staining and a counterstain enhanced fluorescence technique (chromomycin A₃/distamycin A/DAPI-staining = CDD-method) and G-banding, respectively, have been applied to the zebu (Bos indicus L.) chromosomes. The nucleolus organizer regions (NORs) were found in the telomeric regions of chromosomes nos. 2, 3, 4, 11, and 28. CDD staining led to a well-defined R-banding pattern along the chromosome arms and to the visualization of centric heterochromatic bands of variable sizes.     

Molecular structure of the bilin binding protein (BBP) from Pieris brassicae after refinement at 2.0 A resolution

The bilin binding protein (BBP) from the insect Pieris brassicae has been analysed for amino acid sequence, spectral properties and three-dimensional structure. The crystal structure that had been determined by isomorphous replacement has been refined at 2.0 A (1 A = 0.1 nm) resolution to an R-value of 0.20. The asymmetric unit contains four independent subunits of BBP. The co-ordinate differences are 0.25 A, in accord with the estimated error in co-ordinates. The polypeptide chain fold is characterized by an eight-stranded barrel. The connecting loops splay out at the upper end of the barrel and open it, whilst the lower end is closed. The overall shape resembles a calyx. The biliverdin IX gamma chromophore is located in a central cleft at the upper end of the barrel. The bilatriene moiety is in cyclic helical geometry with configuration Z,Z,Z and conformation syn,syn,syn. The geometry is in accord with the spectral properties and permits a correlation between sign of the circular dichroism bands and sense of the bilatriene helices. The fold of BBP is related to retinol binding protein (RBP), as had been recognized in the preliminary analysis, although the amino acid sequences of RBP and BBP show only 10% homology. There are large differences in the loops at the upper end of the barrel, whilst the segments of the centre and the lower end of the barrel superimpose closely. The ligands of BBP and RBP, biliverdin and retinol, respectively, are also similarly located.     

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.