A case of biodiversity overestimation in the Balkan Belgrandiella A. J. Wagner, 1927 (Caenogastropoda: Hydrobiidae): molecular divergence not paralleled by high morphological variation

Belgrandiella A. J. Wagner, 1927 is a genus comprising minute snails with conic or turriform shells that are facultative stygobionts, inhabiting subterranean waters and springs. Few specimens or even empty shells of this taxon can be found, so the taxonomy is based mostly on the shell morphology and geographic distribution. Anatomy is known for a few taxa, and its usefulness is restricted. This, coupled with a popular idea that isolation is the first factor shaping divergence and speciation of the spring/cave fauna, resulted in dozens of nominal species of Belgrandiella, known from shells at a given locality. Herein we present shells, anatomy and four molecular markers (nuclear H3, 18S and 28S and mitochondrial cytochrome oxidase subunit I) in Belgrandiella from 16 localities in Slovenia, northern Croatia, and Bosnia and Herzegovina. Five sites are type localities of Boleana umbilicata, Belgrandiella kusceri, Belgrandiella krupensis, Belgrandiella zermanica and Belgrandiella robusta, respectively. Considering the shell and geographic distribution, we have determined B. cf. robusta Belgrandiella cf. croatica, Belgrandiella cf. fontinalis, Belgrandiella cf. kuesteri, Belgrandiella cf. pageti and Belgrandiella cf. koprivnensis The shells of all, as well as penes and female reproductive organs of two putative, species have been illustrated. Molecular analysis indicates four distinct clades, most probably of species rank for B. kusceri, B. cf. kuesteri, B. cf. fontinalis and B. cf. koprivnensis. Four nominal species (B. krupensis, B. robusta, B. umbilicata and B. zermanica) and one genus (Boleana) must be synonymised with Belgrandiella kusceri, and there are no more than four valid, biological species in the studied Belgrandiella. The molecular divergence is completely unmirrored by high morphological variability. Hence the level of endemism is markedly overestimated in these snails.     

Toward a History of Mathematics Focused on Procedures

Abraham Robinson’s framework for modern infinitesimals was developed half a century ago. It enables a re-evaluation of the procedures of the pioneers of mathematical analysis. Their procedures have been often viewed through the lens of the success of the Weierstrassian foundations. We propose a view without passing through the lens, by means of proxies for such procedures in the modern theory of infinitesimals. The real accomplishments of calculus and analysis had been based primarily on the elaboration of novel techniques for solving problems rather than a quest for ultimate foundations. It may be hopeless to interpret historical foundations in terms of a punctiform continuum, but arguably it is possible to interpret historical techniques and procedures in terms of modern ones. Our proposed formalisations do not mean that Fermat, Gregory, Leibniz, Euler, and Cauchy were pre-Robinsonians, but rather indicate that Robinson’s framework is more helpful in understanding their procedures than a Weierstrassian framework.     

Testosterone metabolism by mouse placenta in vitro

Zusammenfassung 4-C¹⁴-Testosteron wurde durch Mäuseplazenta in vitro zu Steroiden umgesetzt: 3-Hydroxy-5-androstan-3, 17-dion, 3-Hydroxy-5-androstan-3, 17-dion, 4-Androsten-3, 17-dion und 5-Androstan-3, 17-dion. Eine Umsetzung von Testosteron zu Östrogenen wurde nicht nachgewiesen.     

Decondensation of nuclear chromatin under the influence ofTris buffer

Résumé Des petits fragments de foie de rat ont été maintenus dans un tampon 2 mM tris HCl avec ou sans saccharose (concentration final 0,25M). L'incubation du tissus pendant au moins 1 h dans le tampontris cause une décondensation de la chromatine, qui peut être retardée par le saccharose. Les changements morphologiques des types de chromatine n'ont pas l'effet d'incorporer l'uridine dans le noyaux interphasiques du foie.     

The threshold osmotic reactivity of the hypothalamo-hypophyseal antidiuretic system and of the thirst mechanism

Résumé On a examiné la réactivité osmotique du système antidiurétique hypothalamo-hypophysaire et du mécanisme de la soif chez des chiens non narcotisés. Chez tous les animaux examinés, le système antidiurétique s'est montré plus sensible aux stimulus osmotiques que le mécanisme de la soif. On peut supposer que c'est le système antidiurétique qui est activé en premier lieu lors d'un déficit d'eau.     

Gravitational redshift of galaxies in clusters as predicted by general relativity

The theoretical framework of cosmology is mainly defined by gravity, of which general relativity is the current model. Recent tests of general relativity within the Lambda Cold Dark Matter (ΛCDM) model have found a concordance between predictions and the observations of the growth rate and clustering of the cosmic web. General relativity has not hitherto been tested on cosmological scales independently of the assumptions of the ΛCDM model. Here we report an observation of the gravitational redshift of light coming from galaxies in clusters at the 99 per cent confidence level, based on archival data. Our measurement agrees with the predictions of general relativity and its modification created to explain cosmic acceleration without the need for dark energy (the f(R) theory), but is inconsistent with alternative models designed to avoid the presence of dark matter.     

Some properties of external NADH oxidation by human placental mitochondria

Summary Isolated human term placenta mitochondria catalyse oxidation of external NADH in the presence of cytochrome c. This reaction is insensitive to the respiratory chain inhibitors such as rotenone and antimycin A, and is not coupled to phosphorylation. Comparison of the effect of Mg⁺⁺ ion on NADH plus cytochrome c oxidation by human term placental, human skeletal muscle and rat skeletal mitochondria showed that Mg⁺⁺ ion exerts an inhibitory effect in the case of human mitochondria and a stimulatory effect in the case of rat skeletal muscle mitochondria.This work has been supported by a grant from Ministry of Higher Education Science and Technology within the project No. 01.02.     

Head swivel on the ribosome facilitates translocation by means of intra-subunit tRNA hybrid sites

The elongation cycle of protein synthesis involves the delivery of aminoacyl-transfer RNAs to the aminoacyl-tRNA-binding site (A?site) of the ribosome, followed by peptide-bond formation and translocation of the tRNAs through the ribosome to reopen the A?site. The translocation reaction is catalysed by elongation factor G (EF-G) in a GTP-dependent manner. Despite the availability of structures of various EF-G-ribosome complexes, the precise mechanism by which tRNAs move through the ribosome still remains unclear. Here we use multiparticle cryoelectron microscopy analysis to resolve two previously unseen subpopulations within Thermus thermophilus EF-G-ribosome complexes at subnanometre resolution, one of them with a partly translocated tRNA. Comparison of these substates reveals that translocation of tRNA on the 30S subunit parallels the swivelling of the 30S head and is coupled to unratcheting of the 30S body. Because the tRNA maintains contact with the peptidyl-tRNA-binding site (P?site) on the 30S head and simultaneously establishes interaction with the exit site (E?site) on the 30S platform, a novel intra-subunit 'pe/E' hybrid state is formed. This state is stabilized by domain?IV of EF-G, which interacts with the swivelled 30S-head conformation. These findings provide direct structural and mechanistic insight into the 'missing link' in terms of tRNA intermediates involved in the universally conserved translocation process.     

New species of Notophthiracarus (Acari: Oribatida: Phthiracaroidea) from Tanzania

Three new species of the genus Notophthiracarus are described, identified and figured from Uluguru Mountains of Tanzania: Notophthiracarus quasiuluguruensis sp. nov, Notophthiracarus tuberculus sp. nov, and Notophthiracarus uluguruensis sp. nov. A comparison with the most closely related species of the genus Notophthiracarus is also presented.

http://zoobank.org/urn:lsid:zoobank.org:pub:3FBF24E7-3E2D-4686-AD57-EFEA25510BBD