Lipiniella arenicola (Chironomidae) compared withChironomus muratensis andCh. nudiventris: Distribution patterns related to depth and sediment characteristics,diet, and behavioural response to reduced oxygen concentrations

Density patterns ofLipiniella arenicola andChironomus muratensis were studied in Lake Wolderwijd (The Netherlands) using geostatistics, and compared with patterns of depth and silt contents of the sediment.L. arenicola was restricted to shallow (depth <1 m), sandy silt (silt content <5%), wind-exposed sediments.Ch. muratensis occurred all over the lake, but the highest densities were found in the sheltered silty North-West corner. Gut analyses of IV-instar larvae from the Ventjagers flats (Haringvliet, Lower Rhine-Meuse) showed thatL. arenicola fed by selectively grazing on benthic algae,Ch. muratensis by filtering and non-selective grazing, andCh. nudiventris by non-selective grazing. In the laboratory, behavioural responses to reduced oxygen concentrations were tested with the impedance conversion technique.L. arenicola was more sensitive to low oxygen concentrations (<3 mg l^–1) than bothChironomus species. It is argued that the differences in resistance to hypoxia and feeding behaviour are in accordance with the differences in distribution patterns. The restriction ofL. arenicola to the pure sand habitats is not attributable to an especially high sensitivity to low dissolved oxygen concentrations alone. Several behavioural adaptations enableL. arenicola larvae to live in the shallow, wind-exposed pure-sand habitats: the ability to select food items, tube strength, and site selection of ovipositing females or planktonic larvae.     

Synthesis,antimalarial activities and cytotoxicities of amino-artemisinin-1,2-disubstituted ferrocene hybrids

Artemisinin-ferrocene conjugates incorporating a 1,2-disubstituted ferrocene analogous to that embedded in ferroquine but attached via a piperazine linker to C10 of the artemisinin were prepared from the piperazine artemisinin derivative, and activities were evaluated against asexual blood stages of chloroquine (CQ) sensitive NF54 and CQ resistant K1 and W2 strains of Plasmodium falciparum (Pf). The most active was the morpholino derivative 5 with IC₅₀ of 0.86?nM against Pf K1 and 1.4?nM against Pf W2. The resistance indices were superior to those of current clinical artemisinins. Notably, the compounds were active against Pf NF54 early and late blood stage gametocytes – these exerted >86% inhibition at 1?µM against both stages; they are thus appreciably more active than methylene blue (～57% inhibition at 1?µM) against late stage gametocytes. The data portends transmission blocking activity. Cytotoxicity was determined against human embryonic kidney cells (Hek293), while human malignant melanoma cells (A375) were used to assess their antitumor activity.     

Nuclear magnetic resonance‐based determination of dioxygen binding sites in protein cavities

The location and ligand accessibility of internal cavities in cysteine‐free wild‐type T4 lysozyme was investigated using O₂ gas‐pressure NMR spectroscopy and molecular dynamics (MD) simulation. Upon increasing the concentration of dissolved O₂ in solvent to 8.9 mM, O₂‐induced paramagnetic relaxation enhancements (PREs) to the backbone amide and side chain methyl protons were observed, specifically around two cavities in the C‐terminal domain. To determine the number of O₂ binding sites and their atomic coordinates from the 1/r⁶ distance dependence of the PREs, we established an analytical procedure using Akaike's Information Criterion, in combination with a grid‐search. Two O₂‐accessible sites were identified in internal cavities: One site was consistent with the xenon‐binding site in the protein in crystal, and the other site was established to be a novel ligand‐binding site. MD simulations performed at 10 and 100 mM O₂ revealed dioxygen ingress and egress as well as rotational and translational motions of O₂ in the cavities. It is therefore suggested that conformational fluctuations within the ground‐state ensemble transiently develop channels for O₂ association with the internal protein cavities.     

Importance of mitochondrial transmembrane processes in human mitochondriopathies

In a substantial group of subjects suspected to have a mitochondriopathy no defect in the mitochondrial energy metabolism (pyruvate dehydrogenase complex or respiratory chain complexes) can be demonstrated. At least in some of these subjects it seems justified to consider a defect in one of the proteins which mediate the transport of several ions and substrates across the mitochondrial membranes. Of particular interest are proteins which are directly involved in the process of oxidative phosphorylation, such as the adenine nucleotide translocator (ANT) and the phosphate carrier (PiC). However, defects in transmembrane ion transporters also may induce impaired energy metabolism probably as a result of osmotic disturbances within the mitochondrial matrix. In this respect, the voltage-dependent anion channel (VDAC) and other ion channels have to be taken into consideration. Here we review the still incomplete knowledge of the occurrence of ANT, PiC, VDAC, cation channels, and a few substrate carriers in human tissues, as well as their possible role in pathology.     

Differential expression of the Sesbania rostrata leghemoglobin glb3 gene promoter in transgenic legume and non-legume plants

The involvement of the Sesbania rostrata glb3 gene promoter NICE (nodule-infected cell expression) element in root-enhanced expression of 5-Srglb3-uidA-3nos chimeric gene was investigated in transgenic Nicotiana tabacum plants. The full-length wild-type Srglb3 promoter directed root meristem-enhanced expression in transgenic tobacco plants. The expression pattern of nine selected Srglb3 promoter mutations in the NICE element was examined in transgenic tobacco plants and compared with the pattern observed in nodules of transgenic Lotus corniculatus plants. The results suggest that the highly conserved motifs in the NICE element play an important role in expression in roots of non-legume plants.     

Linkage analysis in a Dutch family with X-linked recessive congenital stationary night blindness (XL-CSNB)

Linkage analysis has been performed in a large Dutch pedigree with X-linked recessive congenital stationary night blindness (CSNB) by utilizing 16 DNA markers from the proximal short arm of the human X chromosome (Xp21.1-11.2). Thirteen polymorphic markers are at least partially informative and have enabled pairwise and multipoint linkage analysis. For three loci, i. e. DXS228, the monoamine oxidase B gene and the Norrie disease gene (NDG), multipoint linkage studies have yielded maximum lod scores of >3.0 at a recombination fraction of zero. Analysis of recombination events has enabled us to rule out the possibility that the underlying defect in this family is allelic to RP3; the gene defect could also be excluded from the proximal part of the region known to carry RP2. Linkage data are consistent with a possible involvement of the NDG but mutations in the open reading frame of this gene have not been found.     

The reproductive behavior of golden monkeys in captivity (Rhinopithecus roxellana roxellana)

The reproductive behavior of two captive harem breeding groups of golden monkeys was observed over one mating season and compared to non-seasonal reproductive behavior. Observation of over two thousand sexual interactions suggests that 1) females were responsible for 95% of all sexual solicitations (proceptive behavior), of which the typical pattern was prostration, while males were responsible for only 5%; 2) 17% of female solicitations were interrupted by another female; 3) 52% of female solicitations resulted in mounting by males; 4) the frequencies of solicitations and receipt of mounts and ejaculations varied greatly among females; 5) the frequency of ejaculations, the ratio of ejaculations to mountings, and ejaculation patterns were different between two males, and 6) the golden monkey is a seasonal breeding animal.     

Pollination and stigma wounding: same response, different signal?

In Petunia hybrida flowers, both pollination and stigma woundinginduced a transient Increase in ethylene production and hastenedcorolla senescence. Ethylene production by different flowerparts was measured in situ using laser photoacoustic (LPA) spectroscopy.In pollinated flowers, ethylene was exclusively produced bythe stigma/style region whereas wounding of the stigma Inducedethylene production both by the stigma/style region and by theremaining flower parts. In aminoethoxyvinylglycine (AVG)-treatedflowers, subsequent treatment of the unwounded stigma with 1-aminocyclopropane-1-carboxylicacid (ACC) induced ethylene production exclusively by the stigma/styleregion whereas treatment of a previously wounded stigma withACC induced a simultaneous increase in ethylene production bythe stigma/style region and the remaining flower parts. Theseresults suggest that following stigma wounding, either ACC orethylene is involved in inter-organ communication. Followingpollination, the signal is apparently not directly related toethylene. In vivo ACC oxidase activity of most flower parts, includingthe gynoecium, was higher in light than in dark. Light or darkdid not influence the relative contributions of stigma/styleand remaining flower parts to the total pollination, woundingor ACC-induced ethylene production, indicating that ACC is nottranslocated. Both in excised styles and intact flowers, radiolabelledACC and its analogue -aminoisobutyric acid (AIB), applied eitherto an intact or wounded stigma, were largely immobile confirmingthat ACC is not likely to play a role in inter-organ signalling. The results collectively suggest that following stigma wounding,translocation of ethylene may be the signal responsible forinitiation of corolla senescence; following pollination thesignal is not directly related to ethylene. Key words: 1-Aminocyclopropane-1-carboxylic acid (ACC), ethylene, flower senescence, Petunia hybrida, pollination, stigma wounding