Lazy ecologist's guide to water beetle diversity: Which sampling methods are the best?

Biodiversity surveys of aquatic macroinvertebrates in standing water rely on various methods, but a thorough comparison of the techniques is lacking. This hampers analyses across surveys and impedes development of efficient sampling schemes. We compare the selectivity and efficiency of four methods commonly used to collect aquatic insects – activity traps (ATs), box trap (BT), handnetting (HN) and light trap (LT) – using a large dataset on water beetles in a site with ～100 species. We propose to use time investment as a natural basis to compare efficiency, since it applies to any method. The results inherently differ from results based on samples or individuals because methods are neither equally demanding nor equally rewarding. Most differences between methods arise from their size selectivity: ATs select for larger species, while HN and BT seem least selective. Attraction to light is taxon-specific and LT yields more depauperate samples than ATs, BT and HN, limiting the use of LT in community studies. To boost the development of cost-effective protocols, we also identify the best designs for rapid bioassesment by simulating short surveys from the data. Combinations of ATs and BT give most species; the results are robust to partitioning of effort between both methods. However, these rapid surveys miss on average more than 40% of all species in our study. Our results therefore emphasize that long-term studies using multiple methods are vital for measuring diversity in species-rich freshwater habitats.     

The Oscillopolarographic Behaviour of Deoxyribonucleic Acids Isolated from Bacillus Subtilis and Bacillus brevis

Summary The behaviour of DNA from several strains ofB. subtilis andB. brevis on the dropping mercury electrode in a medium of ammonium formate was studied. Native DNA yields in this medium on the oscillogram dE/dt againstE an anodic indentation for which the residues of deoxyguanylic acid are responsible.B. subtilis DNA produces a substantially smaller indentation thanB. brevis DNA does. It was found that the difference is not conditioned by impurities in the DNA samples, nor by the presence of denatured DNA. The difference in the depth of the indentation produced byB. subtilis andB. brevis DNAs almost disappears after denaturation of these DNAs or in an ammonium formate medium of higher concentration. The assumption was advanced that the different oscillopolarographic behaviour of DNAs obtained fromB. subtilis andB. brevis is connected with the different primary structure of these DNAs.     

Pulsed Regime of the Diffusive Mode of a Barrier Discharge in Helium

Periodic pulsations of the active current component are revealed experimentally in transversely homogeneous barrier discharges in helium at small values of the parameter Pd (below 500 torr mm) and moderate frequencies of the applied voltage (f < 100 kHz). The frequency of the current pulsations is higher than the frequency of the well-studied pulsations in a transversely inhomogeneous streamer barrier discharge in air by a factor of approximately 100. Numerical calculations show that the physical nature of the observed pulsations can be explained in terms of the negative differential resistance of the cathode fall region, which occupies essentially the entire interelectrode gap in each half-period of the applied voltage.     

Evidence of a genetically distinct population of Vrljika softmouth trout Salmo obtusirostris Heckel evolved by vicariance

Mitochondrial DNA haplotypes (control region, partial cytochrome b and ATPase6 genes) indicate a sister relationship between Vrljika and Neretva softmouth (Adriatic) trout Salmo obtusirostris . This relationship was supported by a tree of individuals based on microsatellite results [allele sharing distances ( D _AS)], which revealed three distinctive clusters, corresponding to Jadro softmouth, Neretva brown trout Salmo trutta and Neretva softmouth trout. Within the latter taxon, Vrljika trout are clearly separated from other trout. The genetic results contradict the synonymy of Jadro with Vrljika softmouth trout, as recently proposed in the Red Book of Freshwater Fish in Croatia. Vrljika softmouth trout appear to have originated from a vicariance that split a common ancestor into large (Neretva) and small (Vrljika) fragmented populations 135 000–270 000 years ago. Vrljika softmouth trout can be distinguished by an array of derived phenotypic and molecular character states. For conservation, this population should be recognized formally at the same taxonomic level as the other geographically separated populations of softmouth trout.     

Mutation affecting normal colony formation inEscherichia coli K-12

The effect of a mutation in a gene located near thepro marker and determining the normal colony formation and the cell density inEscherichia coli has been analyzed. Thencf mutation has no effect on the permeability of the cell to actinomycin D. On the other hand, a higher level of ATP and a defect in the accumulation of the reserve material in the mutant cell were detected.     

Synthesis of a series of fully methylated aldobiouronic acids,and β-elimination reactions of their synthetic precursors

Treatment of methyl 2,3,4-tri-O-acetyl-l-bromo-l-deoxy-α-d-glucopyranuronate severally with 2,4,6-, 2,3,6-, and 2,3,4-tri-O-methyl derivatives of methyl α-d-glucopyranoside and with methyl 4,6-O-benzylidene-3-O-methyl-α-d-glucopyranoside, in the presence of silver carbonate, afforded crystalline aldobiouronic acid derivatives in high yield. Deacetylation followed by methylation gave a series of fully methylated derivatives of laminaribiouronic, cellobiouronic, and gentiobiouronic acids, and the (1 → 2)-linked analogue. Methylation with methyl iodide and silver oxide in N,N-dimethylformamide was invariably accompanied by a small amount ofβ-elimination, with the formation of olefinic disaccharides which were also obtained by β-elimination reactions of the precursor acetates followed by methylation. Methyl 4,5-unsaturated 4-deoxyhexopyranosyluronate derivatives were the main products of the reaction, but these underwent further degradation with cleavage of the interglycosidic linkage and formation of 6-methoxycarbonyl-4-pyrone.     

Mutagenic effects of short term action of N-methyl-N’-nitro-N-nitrosoguanidine onChlamydomonas geitleri

A possible method of finding the best concentration of a chemical mutagen or a shortterm action is demonstrated by the results obtained withChlamydomonas geitleri. Mostly two cases occur. We must either use the shortest time of the mutagen action with a sufficiently high effect or utilize the whole limited time for this action using a suitable concentration with a similar effect. It is possible to choose such a structure of the doae of the chemical mutagen which in the mutation spectrum ensures either the optimal frequencies of all components or of only some of them chosen beforehand.