Cladocera in space and time: Analysis of lake sediments

Shells of Bosminidae and Chydoridae are quantitatively preserved in lake sediments. The chronological deposition of these remains provides the means for longterm observation of these Cladocera, both in terms of species and communities. Chydorid analysis, as based on subfossil assemblages, is an analysis of community and provides direct observation of community dynamics over extended periods of time. It has proved to be a valuable method to obtain information on the influence of environmental factors and time on community characteristics. Morphological variation inBosmina (Eubosmina) has been followed for some thousand years. This is of special interest for the evaluation of taxonomic rank (species, forms) if closely related taxa have co-existed. Bosmina successions, as well as shifts in the chydorid fauna, are related to environmental change. Thus, cladoceran analysis of lake sediments provides information on the developmental history of lakes and allows observation of the effects of longterm environmental changes, such as climatic changes and eutrophication.     

Crystallization and preliminary x-ray diffraction studies of recombinant human interleukin-1 beta

Recombinant human interleukin-1 beta has been crystallized into a tetragonal cell. The unit cell constants are a = b = 54.9 A, c = 76.8 A, and alpha = beta = gamma = 90 degrees. The crystals diffract to better than 1.9 A and are suitable for high resolution data collection. The crystallization conditions and general crystal data are presented.     

Fast charge translocations associated with partial reactions of the Na,K-pump: II. Microscopic analysis of transient currents

Summary Nonstationary pump currents which have been observed in K⁺-free Na⁺ media after activation of the Na,K-ATPase by an ATP-concentration jump (see the preceding paper) are analyzed on the basis of microscopic reaction models. It is shown that the behavior of the current signal at short times is governed by electrically silent reactions preceding phosphorylation of the protein; accordingly, the main information on charge-translocating processes is contained in the declining phase of the pump current. The experimental results support the Albers-Post reaction scheme of the Na,K-pump, in which the translocation of Na⁺ precedes translocation of K⁺. The transient pump current is represented as the sum of contributions of the individual transitions in the reaction cycle. Each term in the sum is the product of a net transition rate times a dielectric coefficient describing the amount of charge translocated in a given reaction step. Charge translocation may result from the motion of ion-binding sites in the course of conformational changes, as well as from movement of ions in access channels connecting the binding sites to the aqueous media. A likely interpretation of the observed nonstationary currents consists in the assumption that the principal electrogenic step is the E₁-P/P-E₂ conformational transition of the protein, followed by a release of Na⁺ to the extracellular side. This conclusion is supported by kinetic data from the literature, as well as on the finding that chymotrypsin treatment which is known to block the E₁-P/P-E₂ transition abolishes the current transient. By numerical simulation of the Albers-Post reaction cycle, the proposed mechanism of charge translocation has been shown to reproduce the experimentally observed time behavior of pump currents.     

A new infrageneric classification and phylogenetic trends in the genusRhododendron (Ericaceae)

Recent studies have improved the infrageneric classification ofRhododendron, including my own investigations on flavonoids and anthocyanins as chemosystematic markers. From a synoptical comparison of morphological, anatomical and phytochemical characters a new system for the genus is proposed. Phylogenetic character progressions and relationships among subgenera, sections and subsections are discussed and illustrated. Key positions for subg.Candidastrum between chori subgenerumRhododendron andNomazalea, and for subg.Choniastrum between chori subgenerumHymenanthes andNomazalea are suggested.     

Genome relationship betweenPsathyrostachys huashanica andP. fragilis (Poaceae)

Hybrids between the Chinese endemic speciesPsathyrostachys huashanica Keng and the SW. Asian speciesP. fragilis (Boiss.)Nevski (all 2n = 14) developed normally but were completely sterile. Meiotic analyses revealed a high chiasma frequency indicating that the two species as well asP. juncea (Fisch.)Nevski share the same basic genome (called N). The hybrid nature of the plants was established through karyotype analysis and Giemsa C-banding.     

On the carrying behaviour of basic South American primates

InCallithrix, Saguinus, Aotus, andCallicebus other group members than the mother participate in infant care. Differences among these species are obvious in respect to the time of being off any caregiver, and in respect to the carrying position (Aotus andCallicebus). Alloparental care, a basic behaviour pattern in these species, has evolved from the parking behaviour of the prosimians. The infants are «parked» at other group members.     

A phylogenetic study of the antenna cleaner in Formicidae,Mutillidae, and Tiphiidae (Insecta,Hymenoptera)

Summary The morphology of the tibio-tarsal antenna cleaner (strigilis) of 30 species of Formicidae, 14 species of Mutillidae and 9 species of Tiphiidae was investigated and is described comparatively. In Formicidae, there is a common type of strigilis. The spur has a posterior-dorsal comb and its anterior side is covered with squamae, which usually form a brush. Posteriorly, the basitarsal notch bears a comb and anteriorly specialized paddle-shaped hairs. These characters may be apomorphic for Formicidae. In several Ponerinae and in Myrmecia there is also a velum on the spur. In two species of ants which are strongly parasitic (Teleutomyrmex schneideri and Anergates atratulus ) there are reduced antenna cleaners. Mutillidae (except Myrmosa) have another common type of strigilis: the spur bears a velum with a smooth rim and a clear apex with two rows of teeth. The notch in the basitarsus is usually deeper than that of ants; there is a comb, but no paddle-shaped hairs. The strigilis of Myrmosa females has no velum but there are two prominent rows of teeth on the spur. In the male, the velum is reduced to a slender strip. In Tiphiidae the antenna cleaners show considerable diversity. In Methocha the spur bears a comb but no velum; the spur of Tiphia has a velum with a serrated rim; the spur of Myzinum is equipped with a velum with a smooth rim; in Thynnus the surface of the velum is wrinkled or undulating. An apex (without teeth) is present in all investigated Tiphiidae. The notch of the basitarsus bears a comb except in female Myzinum, where the teeth seem to have fused, thus forming a rim. It is suggested that a velum with a serrated or toothed edge and an apex with two rows of teeth are plesiomorphic for aculeate Hymenoptera. The antenna cleaners in Mutillidae are remarkably similar to those in some bees. This fact is interpreted as partly due to convergence and as partly symplesiomorphic. In several species of ants, there is a specialized cuticular area (bande poreuse) anterior to the comb of the notch, which is characterized by fissures or holes. These are presumably openings of an excretory gland.     

Naturally occurring monoterpenoids in needles of Picea abies (L.) Karst

Summary An analysis was made of the effects of different sampling and extraction techniques on the amounts and pattern of monoterpenoids isolated from needles of Norway spruce. The following isolation and analysis procedure was finally adopted: liquid nitrogen-cooled needles were pulverized by a microdismembrator, extracted with pentane overnight at 2°–3°C and concentrated to a volume not less than 3 ml/g fresh weight on a Vigreux column. The crude extract was injected splitless (with solvent split) onto a cold programmed temperature vaporized (PTV) precolumn of a gas chromatograph and the vaporizable compounds heated to a capillary column. This method was tested for production of artefacts and quantitative extraction and applied to needles of eleven 80-year-old spruce trees.     

Importance of Hydrogen Sulfide, Thiosulfate, and Methylmercaptan for Growth of Thiobacilli during Simulation of Concrete Corrosion

Biogenic sulfuric acid corrosion of concrete surfaces caused by thiobacilli was reproduced in simulation experiments. At 9 months after inoculation with thiobacilli, concrete blocks were severely corroded. The sulfur compounds hydrogen sulfide, thiosulfate, and methylmercaptan were tested for their corrosive action. With hydrogen sulfide, severe corrosion was noted. The flora was dominated by Thiobacillus thiooxidans. Thiosulfate led to medium corrosion and a dominance of Thiobacillus neapolitanus and Thiobacillus intermedius. Methylmercaptan resulted in negligible corrosion. A flora of heterotrophs and fungi grew on the blocks. This result implies that methylmercaptan cannot be degraded by thiobacilli.     

Transposon Mutants of Bradyrhizobium japonicum Altered in Attachment to Host Roots

Transposon mutants of Bradyrhizobium japonicum 110 ARS were produced and screened for changes in attachment ability. Mutant CFK4 produced twice as many piliated cells, attached in 2.5-fold-higher numbers to soybean root segments, and colonized roots in about 2-fold-higher numbers than did the parental strain, 110 ARS. Mutants CFK35 and CFK38 were reduced in their attachment about 2-fold and 3.5-fold, respectively. This corresponded to reductions in piliated cells in their populations, reduced reaction with anti-pilus antiserum, and reduced hydrophobic attachment. Mutants CFK4 and CFK38 nodulated soybeans at about the same level as the parent strain, but CFK35 induced only pseudonodules. Two-dimensional gel analyses of the proteins from the mutants showed relatively few changes in proteins.