Recycling,reproduction, and life's origins

Kinetic considerations make it most improbable that any reproducing system could arise spontaneously in a prebiotic soup containing a large variety of organic molecules, as commonly postulated. This batch process can be contrasted with a completely recycling network of reactions maintained by an influx of energy. So long as the network includes at least two bimolecular reactions it is likely to support pathways for chemical reproduction. However, such reproducing systems will be simple in both kinetic and structural terms. Subsequent evolution will lead to much more complex reproducing structures although the kinetic complexities, measuring the varieties of reactions between these structures and their media, will remain relatively simple.     

Kynurenines,neurodegeneration and Alzheimer’s disease

Alzheimer’s disease (AD) is one of the major causes of dementia. The pathogenesis of the disease is not entirely understood, but the amyloid β peptide (Aβ) and the formation of senile plaques seem to play pivotal roles. Oligomerization of the Aβ is thought to trigger a cascade of events, including oxidative stress, glutamate excitotoxicity and inflammation. The kynurenine (KYN) pathway is the major route for the metabolism of the essential amino acid tryptophan. Some of the metabolites of this pathway, such as 3-hydroxykynurenine and quinolinic acid, are known to have neurotoxic properties, whereas others, such as kynurenic acid, are putative neuroprotectants. Among other routes, the KYN pathway has been shown to be involved in AD pathogenesis, and connections to other known mechanisms have also been demonstrated. Oxidative stress, glutamate excitotoxicity and the neuroinflammation involved in AD pathogenesis have been revealed to be connected to the KYN pathway. Intervention at these key steps may serve as the aim of potential therapy.     

Empathy’s purity,sympathy’s complexities; De Waal,Darwin and Adam Smith

Frans de Waal’s view that empathy is at the basis of morality directly seems to build on Darwin, who considered sympathy as the crucial instinct. Yet when we look closer, their understanding of the central social instinct differs considerably. De Waal sees our deeply ingrained tendency to sympathize (or rather: empathize) with others as the good side of our morally dualistic nature. For Darwin, sympathizing was not the whole story of the “workings of sympathy”; the (selfish) need to receive sympathy played just as central a role in the complex roads from sympathy to morality. Darwin’s understanding of sympathy stems from Adam Smith, who argued that the presence of morally impure motives should not be a reason for cynicism about morality. I suggest that De Waal’s approach could benefit from a more thorough alignment with the analysis of the workings of sympathy in the work of Darwin and Adam Smith.     

« Statut de Berger » des communautés atlasiques, néolithisées du Maghreb oriental, dès 7000 BP

Neolithization through karstic rocky territories from Eastern Maghreb is supported by a special form of pastoralism. Between 7000-5000 BP, a prominent sheep and goat animal husbandry represents a shepherd’ permanent objective, while domestic cattle seems to play a saving role. Aurès reaches allowed us to study a global shepherd living, initiated by small groups, labelled as Neolithic of Capsian Tradition, stricto sensu (NCT). A new approach focuses here on non local archaeological finds from the Capéletti cave, a residential key-site located on the slopes of the Khanguet Si Mohamed Tahar amphitheatre (1540m), gives the lead to explore a winter lowland transhumance behaviour, which was a yearly extension of a summer upland behaviour. Through synchronized data, selected among exotic cultural documents, such as polished stone axes and adzes; marine and ivory-ornaments; and lowland botanic remains from marshes, such as elements of a steppic and salted vegetation, trapped inside sheep fleece, new evidences emerged which were linked, then, with new data based on flocks evaluation as alive animals. This study gives precision on:

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the shepherd’s long term objective;

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the initial and natural animal husbandry which moved, through an empirical management, on an increasing and controlled sheep, goat and cattle breeding;

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the non local cultural goods broad-spectrum, coveted by the shepherds;

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the flock meat/animal goods, coveted by peddling nomadic people;

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the exchange act and its conventions;

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how and when vanished epipaleolithic traditions of this NCT facies, through shepherds’ deliberate and progressive exchanges;

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and how and when, outside farming process, might have appeared, on lowlands and hilly areas, a typical open countryside landscape, strictly linked with this ongoing pastoralism.

This first local Status of the Shepherd which was the main objective of this neolithization may have settled and spread out through Maghreb territories, an Atlasic Pastoral Society.     

Relationships among physical traits,age and social status in Thomson's and Grant's gazelles

Territorial male Thomson's and Grant's gazelles on a commercial game ranch near Nairobi, Kenya, were older, heavier and possessed longer horns than bachelor conspecifics. Among territorial Thomson's gazelles, males accompanied by females were older than solitary individuals but differed little in frame and horn dimensions. Small sample sizes precluded similar analyses for Grant's gazelles. These results suggest the importance of size, age and perhaps experience in determining social status.     

Ruhemann's purple from ninhydrin,ascorbate, and nitrite

Ruhemann's purple is formed from nitrite, ascorbate, and ninhydrin with the formation of variable amounts of ammonia. The reaction begins with the nitrosation of ninhydrin to form nitrosoninhydrin, which will release nitric oxide. The nitrosoninhydrin is reduced by ascorbate to diketohydrindamine, which then couples with a second molecule of ninhydrin to form the pigment. The concentration of pigment is linear with nitrite over the range 1 to 10 mm, but ammonia production is not stoichiometric with initial nitrite.     

Flora, vegetation, and soil in broadleaved ancient and planted woodland, and scrub on RøsnÆs, Denmark

9 small ancient woodlands (>200 years), 9 planted woodland sites (25 — ca. 100 years), and 6 sites in grazed scrub (ca. 100 years) on the RøsnÆs peninsula, Denmark, showed characteristic differences: in ancient woodland, the tree and shrub layer was fairly rich, the field layer rather poor in species. The dominance of spring flowering geophytes, the abundance of Anemone nemorosa , and the occurrence of Corylus avellana and Polygonatum multiflorum were characteristic. pH of the soil was relatively low, organic matter content high, and light intensity at the forest floor in summer low. In planted woodland there was more light, and the field layer was rich in short-lived species, but poor in spring flowering geophytes. Many woodland species were rare in planted woodland, some did not at all occur there, and none were specific for this type of woodland. The scrub was marked by grazing and a strong relief, hence pH was high and organic matter content low. The field layer was rich both in shortlived species and in spring flowering geophytes. — It is suggested that ancient woodland species (i.e. species restricted to or preferably occurring in woodlands existing prior to the enclosure ca. 200 years ago) is a heterogenous group, consisting of a) species favoured by traditional woodland management; b) species restricted to woodlands where specific environmental (e.g. soil) conditions have had sufficient time to develop; c) species with limited ability to spread or establish; or d) species which in ancient woodland are represented by small and scattered populations.     

Bystrow’s Paradox – gills,fossils, and the fish‐to‐tetrapod transition

Schoch, R.R. and Witzmann, F. 2011. Bystrow’s Paradox – gills, fossils, and the fish‐to‐tetrapod transition. —Acta Zoologica (Stockholm) 92 : 251–265. The issue of which breathing mechanism was used by the earliest tetrapods is still unsolved. Recent discoveries of stem tetrapods suggest the presence of internal gills and fish‐like underwater breathing. The same osteological features were used by Bystrow to infer a salamander‐like breathing through external gills in temnospondyl amphibians. This apparent contradiction – here called Bystrow’s Paradox – is resolved by reviewing the primary fossil evidence and the anatomy of the two gill types in extant taxa. Rather unexpectedly, we find that internal gills were present in a range of early crown tetrapods (temnospondyls), based on the anatomy of gill lamellae and location of branchial arteries on the ventral side of gill arch elements (ceratobranchials). Although it remains to be clarified which components are homologous in external and internal gills, both gill types are likely to have been present in Palaeozoic tetrapods – internal gills in aquatic adults of some taxa, and external gills in the larvae of these taxa and in larvae of numerous forms with terrestrial adults, which resorbed the external gills after the larval phase. Future developmental studies will hopefully clarify which mechanistic pathways are involved in gill formation and how these might have evolved.     

LB1’s virtual endocast, microcephaly, and hominin brain evolution

Earlier observations of the virtual endocast of LB1, the type specimen for Homo floresiensis, are reviewed, extended, and interpreted. Seven derived features of LB1's cerebral cortex are detailed: a caudally-positioned occipital lobe, lack of a rostrally-located lunate sulcus, a caudally-expanded temporal lobe, advanced morphology of the lateral prefrontal cortex, shape of the rostral prefrontal cortex, enlarged gyri in the frontopolar region, and an expanded orbitofrontal cortex. These features indicate that LB1's brain was globally reorganized despite its ape-sized cranial capacity (417 cm³). Neurological reorganization may thus form the basis for the cognitive abilities attributed to H. floresiensis. Because of its tiny cranial capacity, some workers think that LB1 represents a Homo sapiens individual that was afflicted with microcephaly, or some other pathology, rather than a new species of hominin. We respond to concerns about our earlier study of microcephalics compared with normal individuals, and reaffirm that LB1 did not suffer from this pathology. The intense controversy about LB1 reflects an older continuing dispute about the relative evolutionary importance of brain size versus neurological reorganization. LB1 may help resolve this debate and illuminate constraints that governed hominin brain evolution.     

Design of orthogonal genetic switches based on a crosstalk map of σs,anti‐σs,and promoters

Cells react to their environment through gene regulatory networks. Network integrity requires minimization of undesired crosstalk between their biomolecules. Similar constraints also limit the use of regulators when building synthetic circuits for engineering applications. Here, we mapped the promoter specificities of extracytoplasmic function (ECF) σ s as well as the specificity of their interaction with anti‐ σ s. DNA synthesis was used to build 86 ECF σ s (two from every subgroup), their promoters, and 62 anti‐ σ s identified from the genomes of diverse bacteria. A subset of 20 σ s and promoters were found to be highly orthogonal to each other. This set can be increased by combining the ?35 and ?10 binding domains from different subgroups to build chimeras that target sequences unrepresented in any subgroup. The orthogonal σ s, anti‐ σ s, and promoters were used to build synthetic genetic switches in Escherichia coli. This represents a genome‐scale resource of the properties of ECF σ s and a resource for synthetic biology, where this set of well‐characterized regulatory parts will enable the construction of sophisticated gene expression programs.