Extension of the Nef reaction to C-glycosylnitromethanes

Acid-catalysed methanolysis of 3,4,5,6-tetra-O-acetyl-1,2-dideoxy-l-arabino-hex-1-enitol proceeds via a cascade set of consecutive reactions resulting in its regiospecific conversion to a mixture of alpha- and beta-C-L-arabinofuranosylmethanal dimethyl acetals and a mixed internal methyl acetal. Structures of the final products of the overall process provide unique evidence that a kinetically controlled, five-membered-ring closure precedes a six-membered-ring closure in reversible systems capable of giving both five-membered and six-membered all-sp3-atom rings. Determination of the reaction intermediate enabled extension of the Nef reaction to C-glycosylnitromethanes. Protonated aci-nitro forms of C-glycosylnitromethanes that are resistant to the Nef reaction in aqueous acidic media undergo a modified Nef reaction in acidified methanol, and the corresponding C-glycosylmethanal dimethyl acetals with alpha-L-arabinopyranosyl, beta-D-glucopyranosyl, beta-D-galactopyranosyl, beta-D-mannopyranosyl and beta-L-rhamnopyranosyl configurations were obtained in moderate yields.     

Static and dynamic human flexor tendon–pulley interaction

The aim of the study was to investigate the influence of a preceding flexion or extension movement on the static interaction of human finger flexor tendons and pulleys concerning flexion torque being generated. Six human fresh frozen cadaver long fingers were mounted in an isokinetic movement device for the proximal interphalangeal (PIP) joint. During flexion and extension movement both flexor tendons were equally loaded with 40 N while the generated moment was depicted simultaneously at the fingertip. The movement was stopped at various positions of the proximal interphalangeal joint to record dynamic and static torque. The static torque was always greater after a preceding extension movement compared to a preceding flexion movement in the corresponding same position of the joint. This applied for the whole arc of movement of 0–105°. The difference between static extension and flexion torque was maximal 11% in average at about 83° of flexion. Static torque was always smaller than dynamic torque during extension movement and always greater than dynamic torque during flexion movement. The kind of preceding movement therefore showed an influence to the torque being generated in the proximal interphalangeal joint. The effect could be simulated on a mechanical finger device.     

A ‘metaphising’ dung beetle

Humans and beetles both have a species-specific Umwelt circumscribed by their sensory equipment. However, Ladislav Kováč argues that humans, unlike beetles, have invented scientific instruments that are able to reach beyond the conceptual borders of our Umwelt.You may have seen the film Microcosmos, produced in 1996 by the French biologists Claude Nuridsany and Marie Perrenou. It does not star humans, but much smaller creatures, mostly insects. The filmmakers'' magnifying camera transposes the viewer into the world of these organisms. For me, Microcosmos is not an ordinary naturalist documentary; it is an exercise in metaphysics.One sequence in the film shows a dung beetle—with the ‘philosophical'' generic name Sisyphus—rolling a ball of horse manure twice its size that becomes stuck on a twig. As the creature struggles to free the dung, it gives the impression that it is both worried and obstinate. As we humans know, the ball represents a most valuable treasure for the beetle: it will lay its eggs into the manure that will later feed its offspring. The behaviour of the beetle is biologically meaningful; it serves its Darwinian fitness.Yet, the dung beetle knows nothing of the function of manure, nor of the horse that dropped the excrement, nor of the human who owned the horse. Sisyphus lives in a world that is circumscribed by its somatic sensors—a species-specific world that the German biologist and philosopher Jakob von Uexküll would have called the dung beetle''s ‘Umwelt''. The horse, too, has its own Umwelt, as does the human. Yet, the world of the horse, just like the world of the man, does not exist for the beetle.If a ‘scholar'' among dung beetles attempted to visualize the world ‘out there'', what would be the dung-beetles'' metaphysics—their image of a part of the world about which they have no data furnished by their sensors? What would be their religions, their truths, or the Truth—revealed, and thus indisputable?Beetles are most successful animals; one animal in every four is a beetle, leading the biologist J.B.S. Haldane to quip that the Creator must have “had an inordinate fondness for beetles”. Are we humans so different from dung beetles? By birth we are similar: inter faeces et urinas nascimur—we are born between faeces and urine—as Aurelius Augustine remarked 1,600 years ago. Humans also have a species-specific Umwelt that has been shaped by biological evolution. A richer one than is the Umwelt of beetles, as we have more sensors than have they. Relative to the body size, we also possess a much larger brain and with it the capacity to make versatile movements with our hands and to finely manipulate with our fingers.This manual dexterity has enabled humans to fabricate artefacts that are, in a sense, extensions and refinements of the human hand. The simplest one, a coarse-chipped stone, represents the evolutionary origins of artefacts. Step-by-step, by a ratchet-like process, artefacts have become ever more complicated: as an example, a Boeing 777 is assembled from more than three million parts. At each step, humans have just added a tiny improvement to the previously achieved state. Over time, the evolution of artefacts has become less dependent on human intention and may soon result in artefacts with the capacity for self-improvement and self-reproduction. In fact, it is by artefacts that humans transcend their biology; artefacts make humans different from beetles. Here is the essence of the difference: humans roll their artefactual balls, no less worried and obstinate than beetles, but, in contrast to the latter, humans often do it even if the action is biologically meaningless, at the expense of their Darwinian fitness. Humans are biologically less rational than are beetles.Artefacts have immensely enriched the human Umwelt. From among them, scientific instruments should be singled out, as they function as novel, extrasomatic sensors of the human species. They have substantially fine-grained human knowledge of the Umwelt. But they are also reaching out—both to a distance and at a rate that is exponentially increasing—behind the boundary of the human Umwelt, behind its conceptual confines that we call Kant''s barriers. Into the world that has long been a subject of human ‘dung-beetle-like'' metaphysics. Nevertheless, our theories about this world could now be substantiated by data coming from the extrasomatic sensors. These instruments, fumbling in the unknown, supply reliable and reproducible data such that their messages must be true. They supersede our arbitrary guesses and fancies, but their truth seems to be out of our conceptual grasp. Conceptually, our mind confines us to our species-specific Umwelt.We continue to share the common fate of our fellow dung beetles: There is undeniably a world outside the confinements of our species-specific Umwelt, but if the world of humans is too complex for the neural ganglia of beetles, the world beyond Kant''s barriers may similarly exceed the capacity of the human brain. The physicist Richard Feynman (1965) stated, perhaps resignedly, “I can safely say that nobody today understands quantum mechanics.” Frank Gannon (2007) likewise commented that biological research, similarly to research in quantum mechanics, might be approaching a state “too complex to comprehend”. New models of the human brain itself may turn out to be “true and effective—and beyond comprehension” (Kováč, 2009).The advances of science notwithstanding, the knowledge of the universe that we have gained on the planet Earth might yet be in its infancy. However, in contrast to the limited capacity of humans, the continuing evolution of artefacts may mean that they face no limits in their explorative potential. They might soon dispense with our conceptual assistance exploring the realms that will remain closed to the human mind forever.     

International Code of Phytosociological Nomenclature. 4th edition

The fourth edition of the International Code of Phytosociological Nomenclature (ICPN) was prepared by the Steering Committee of the IAVS Working Group for Phytosociological Nomenclature (GPN). The edition consists of 14 Definitions, 7 Principles, 53 Articles, and 7 Appendices. When compared with the previous edition, the main amendments are: (a) the acceptance of electronic publications (Art. 1); (b) the introduction of binding decisions (Definition XIV, Principle II, Articles 1, 2b, 3c, 29b, 40, 42, 44, Appendices 6 and 7); (c) the mandatory use of the English or Latin terminology for syntaxonomic novelties (Definition II, Principle II, Articles 3d and 3i); (d) the introduction of autonyms for the main ranks when the corresponding secondary ranks are created (Articles 13b and 24); (e) the automatic correction of the taxon names (name-giving taxa) used in the names of syntaxa in accordance with the International Code of Nomenclature for algae, fungi, and plants (ICN) (Article 44); (f) the possibility to mutate the name of a syntaxon in using other correct, alternative names for the name-giving taxa (Article 45); (g) the introduction of inadequate names, a new category of rejected names (Definition V, Articles 43 through 45); and (h) the introduction of a conserved type (Definition XIII, Article 53). The fourth edition of ICPN was approved by the GPN on 25 May 2019 and becomes effectively binding on 1 January 2021.     

Bilateral MR volumetry of the amygdala in chronic PTSD patients

Posttraumatic stress disorder (PTSD) patients experience symptoms which implicate dysfunction of emotional memory circuits, and possible damage of the amygdala. Laterality differences in activity of the amygdala have been reported in PTSD patients, with presumed adaptive plasticity in the hippocampus and the amygdala. The aim of this study was to investigate possible interhemispheric differences of amygdalar volume in chronic PTSD patients, with calculation of right-to-left volume ratios. Bilateral magnetic resonance (MR) volumetry was applied in 11 chronic PTSD patients. The mean right amygdalar volume of our patients was significantly smaller than the left one (p = 0.031), with the right-to-left volume ratio of 0.96 +/- 0.06. This tendency towards smaller right amygdala may be an acquired effect as a result of stress-induced plasticity, however we can not exclude the possibility of a predisposing condition.     

Identification of a complex peptidergic neuroendocrine network in the hard tick, <Emphasis Type="Italic">Rhipicephalus appendiculatus</Emphasis>

Neuropeptides are crucial regulators of development and various physiological functions but little is known about their identity, expression and function in vectors of pathogens causing serious diseases, such as ticks. Therefore, we have used antibodies against multiple insect and crustacean neuropeptides to reveal the presence of these bioactive molecules in peptidergic neurons and cells of the ixodid tick Rhipicephalus appendiculatus. These antibodies have detected 15 different immunoreactive compounds expressed in specific central and peripheral neurons associated with the synganglion. Most central neurons arborize in distinct areas of the neuropile or the putative neurohaemal periganglionic sheath of the synganglion. Several large identified neurons in the synganglion project multiple processes through peripheral nerves to form elaborate axonal arborizations on the surface of salivary glands or to terminate in the lateral segmental organs (LSO). Additional neuropeptide immunoreactivity has been observed in intrinsic secretory cells of the LSO. We have also identified two novel clusters of peripheral neurons embedded in the cheliceral and paraspiracular nerves. These neurons project branching axons into the synganglion and into the periphery. Our study has thus revealed a complex network of central and peripheral peptidergic neurons, putative neurohaemal and neuromodulatory structures and endocrine cells in the tick comparable with those found in insect and crustacean neuroendocrine systems. Strong specific staining with a large variety of antibodies also indicates that the tick nervous system and adjacent secretory organs are rich sources of diverse neuropeptides related to those identified in insects, crustaceans or even vertebrates. This work was supported by Slovak grant agencies: Agentúra na podporu vyskumu a vyvoja (APVV-51-039105) and Vedecká grantová agentúra (VEGA 2-6090-26 and 2/6155/26).     

Slapylitidae: a new family of hyolithids (Cambrian–?Devonian; Baltica,Laurentia, Gondwana)

Hyoliths are usually preserved as isolated skeletal elements consisting of conch, operculum, and helens. The occurrence of a conch associated with an operculum is ordinarily exceptional, and the co-occurrence of helens with other skeletal parts is a great rarity. The extraordinary finds of hyolithid conchs associated with opercula in situ are relatively abundant in the Cambrian and Ordovician clastic sediments of the Barrandian area in the Czech Republic. The platyclaviculate operculum with clavicles divided by longitudinal walls into channels characterizes members of the newly established family Slapylitidae fam. nov., which includes two genera: Slapylites Marek, 1980 known from the mid-Cambrian of West Gondwana and Baltica and Nevadalites Marek, 1976 documented from the Late Cambrian of Laurentia. To this family most probably belongs also an operculum from the Cambrian Series 2–Series 3 boundary of North Greenland and poorly known material from the Middle Devonian of Bolivia.