The cranial morphology and relationships of the aberrant Carboniferous amphibian Spathicephalus mirus Watson

The skull of Spathicephalus mirus Watson, an amphibian from the Namurian, basal Upper Carboniferous, of Scotland is described. It shares with the Loxommatoidea a closed palate, palatal ornament and antorbital vacuities, and the family Spathicephalidae is recognized as the sister group of the Loxommatidae. A new diagnosis of the Loxommatoidea is presented together with one of the Spathicephalidae. An analysis of the functional morphology of the Spathicephalus skull suggests that it was incapable of rapid jaw closure required for catching fish. Instead it is proposed that Spathicephalus was a sluggish bottom-dwelling filter-feeder of small, soft invertebrates.     

X-ray studies on crystalline complexes involving amino acids and peptides: Part XVIII. Crystal structure of a new form of L-arginine D-glutamate and a comparative study of amino acid crystal structures containing molecules of the same and mixed chirality

The new form of L-arginine D-glutamate is monoclinic, P2₁, witha = 9.941(1),b = 4.668(2),c = 17.307(1) Å,β = 95.27(1)°, and Z = 2. In terms of composition, the new form differs from the old form in that the former is a monohydrate whereas the latter is a trihydrate. The structure has been solved by the direct methods and refined to R = 0.085 for 1012 observed reflections. The conformation of the arginine molecule is the same in both the forms whereas that of the glutamate ion is different. The change in the conformation of the glutamate ion is such that it facilitates extensive pseudosymmetry in the crystals. The molecules arrange themselves in double-layers stabilised by head-to-tail sequences involving main chains, in both the forms. However, considerable differences exist between the two forms in the interface, consisting of side chains and water molecules, between double-layers. A comparative study of the relationship between the crystal structures of L and DL amino acids on the one hand and that between the structures of LL and LD amino acid-amino acid complexes on the other, provides interesting insights into amino acid aggregation and the effect of chirality on it. The crystal structures of most hydrophobic amino acids are made up of double-layers and those of most hydrophilic amino acids contain single layers, irrespective of the chiralities of the amino acids involved. In most cases, the molecules tend to appropriately rearrange themselves to preserve the broad features of aggregation patterns when the chirality of half the molecules is reversed as in the structures of DL amino acids. The basic elements of aggregation in the LL and the LD complexes, are similar to those found in the crystals of L and DL amino acids. However, the differences between the LL and the LD complexes in the distribution of these elements are more pronounced than those between the distributions in the structures of L and DL amino acids.     

Phylogenetic network and physicochemical properties of nonsynonymous mutations in the protein-coding genes of human mitochondrial DNA

Theories on molecular evolution predict that phylogenetically recent nonsynonymous mutations should contain more non-neutral amino acid replacements than ancient mutations. We analyzed 840 complete coding-region human mitochondrial DNA (mtDNA) sequences for nonsynonymous mutations and evaluated the mutations in terms of the physicochemical properties of the amino acids involved. We identified 465 distinct missense and 6 nonsense mutations. 48% of the amino acid replacements changed polarity, 26% size, 8% charge, 32% aliphaticity, 13% aromaticity, and 44% hydropathy. The reduced-median networks of the amino acid changes revealed relatively few differences between the major continent-specific haplogroups, but a high variation and highly starlike phylogenies within the haplogroups. Some 56% of the mutations were private, and 25% were homoplasic. Nonconservative changes were more common than expected among the private mutations but less common among the homoplasic mutations. The asymptotic maximum of the number of nonsynonymous mutations in European mtDNA was estimated to be 1,081. The results suggested that amino acid replacements in the periphery of phylogenetic networks are more deleterious than those in the central parts, indicating that purifying selection prevents the fixation of some alleles.     

1-(t-Butyldimethylsilyloxy) benzotriazole (TBDMS-OBt): A new and novel reagent for the synthesis of peptides

Synthesis and use of 1-(t-butyldimethylsilyloxy)benzotriazole (TBDMS-OBt) in the coupling of Fmoc-amino acid chlorides to amino free amino acid esters in homogeneous solution phase is described. The coupling required no addition of base and was fast and racemization free. Work up and isolation of products were easy. Yield, purity and ¹H NMR analysis of peptides, synthesised by this method, were satisfactory.     

1-(t-Butyldimethylsilyloxy) benzotriazole (TBDMS-OBt): A new and novel reagent for the synthesis of peptides

Summary Synthesis and use of 1-(t-butyldimethylsilyloxy)benzotriazole (TBDMS-OBt) in the coupling of Fmoc-amino acid chlorides to amino free amino acid esters in homogeneous solution phase is described. The coupling required no addition of base and was fast and racemization free. Work up and isolation of products were easy. Yield, purity and¹H NMR analysis of peptides, synthesised by this method, were satisfactory.     

Glycine and Diglycine as Possible Catalytic Factors in the Prebiotic Evolution of Peptides

Mutual catalytic effects within the Salt-Induced Peptide Formation (SIPF) Reaction might be one little puzzle piece in the complicated process of the formation of complex peptidic systems and their chemical evolution on the prebiotic earth. The catalytic effects of glycine and diglycine on the formation of dipeptides from mixed amino acid systems in the SIPF Reaction was investigated for systems with leucine, proline, valine and aspartic acid and showed to result in a significant increase of the yield of the majority of the produced dipeptides. The results of the experiments strongly confirm previous theories on the catalytic mechanism and show the ability of the SIPF Reaction to produce a very diverse set of peptide products with relevance to the formation of a biosphere.     

Molecular identification of schistosome intermediate hosts: case studies of Bulinus forskalii group species (Gastropoda: Planorbidae) from Central and East Africa

African freshwater snails of the genus Bulinus act as intermediate hosts for schistosomes, trematode parasites responsible for medical and veterinary forms of schistosomiasis. The relationship between these snails and their parasites is an intricate one, with particular species of snail susceptible to infection only by certain species of schistosome. In common with other self-fertile hermaphrodite gastropods, Bulinus consists of a number of closely related species complexes with restricted gene flow between populations of each taxon. Consequently, despite their medical and veterinary importance as intermediate hosts, unambiguous identification and differentiation of planorbid snails such as these remains problematic, often confounding attempts to define the distribution and evolutionary relationships of conchologically similar taxa. Here we consider how morphological methods of discrimination can be used in conjunction with molecular based approaches to improve snail identification, thereby achieving a better understanding of the epidemiology of schistosomiasis. Data are presented from Central and East African taxa which illustrate how PCR-based methods have begun to be used in combination with traditional analyses in an integrated approach to characterize the genus Bulinus , specifically the B. forskalii species group. Particular emphasis is given to the analyses of Random Amplified Polymorphic DNA (RAPDs) and the mitochondrial gene cytochrome oxidase I (COI).     

Glutamine as a precursor for transmitter glutamate, aspartate and GABA in the cerebellum: a role for phosphate-activated glutaminase

Phosphate-activated glutaminase is present at high levels in the cerebellar mossy fiber terminals. The role of this enzyme for the production of glutamate from glutamine in the parallel-fiber terminals is unclear. In order to address this, we used light miroscopic immunoperoxidase and electron microscopic immunogold methods to study the localization of glutamate in rat cerbellar slices incubated with physiological K+ (3 mmol/L) and depolarizing K+ (40 mmol/L) concentrations, and during depolarizing conditions with the addition of glutamine and the glutaminase inhibitor 6-diazo-5-oxo-l-norleucine. During K+-induced depolarization glutamate labeling was redistributed from parallel-fiber terminals to glial cells. The nerve terminal content of glutamate was sustained when the slices were supplied with glutamine, which also reduced the accumulation of glutamate in glia. In spite of glutamine supplementation, the depolarized slices treated with 6-diazo-5-oxo-l-norleucine showed depletion of glutamate from parallel-fiber terminals and accumulation in glial cells. We conclude that cerebellar parallel-fiber terminals contain a glutaminase activity enabling them to synthesize glutamate from glutamine. Our results confirm that this is also true for the mossy fiber terminals. In addition, we show that, like for glutamate, the levels of aspartate in parallel-fiber terminals and GABA in Golgi fiber terminals can be maintained during depolarization if glutamine is present. This process is dependent on the activity of a glutaminase, as it can be inhibited by 6-diazo-5-oxo-l-norleucine, suggesting that the glutaminase reaction is important for glutamine to act as a precursor also for aspartate and GABA. The low levels of the kidney type of glutaminase that previously has been shown to be present in the parallel and Golgi fiber terminals could be sufficient to produce the transmitter amino acids. Alternatively, the amino acids could be produced from the liver type of glutaminase, which is not yet localized on the cellular level, or from an unknown glutminase.     

A comparison of fluorescamine and o-phthaldialdehyde as effective blocking reagents in protein sequence analyses by the Beckman sequencer

Use of o-phthaldialdehyde to chemically reduce the newly generated amino termini responsible for the progressively increasing background during an extended amino acid sequence analysis in a liquid phase sequencer has been described. The results have been compared with Fluram blocking using apomyoglobin and rabbit C-reactive protein as standard and unknown samples, respectively.     

Pharmacokinetics of systemically administered tyrosine: a comparison of serum, brain tissue and in vivo microdialysate levels in the rat

Tyrosine uptake has been reported to differ across brain regions. However, such studies have typically been conducted over brief intervals and in anesthetized rats; anesthesia itself affects amino acid transport across the blood-brain barrier. To address these concerns, serum, brain tissue and in vivo microdialysate tyrosine levels were compared for 0-3 h after administration of tyrosine [0.138-1.10 mmol/kg intraperitoneally (i.p.)] to groups of awake rats. Serum and brain tissue tyrosine levels increased linearly with respect to dose. Basal tissue tyrosine levels varied significantly across brain regions [medial prefrontal cortex (MPFC), striatum, hypothalamus, and cerebellum], but the rate of tyrosine uptake was similar for hypothalamus, striatum and MPFC. For brain regions in which tyrosine levels in both microdialysate and tissue were assayed, namely MPFC and striatum, there was a high degree of correlation between tyrosine levels in tissue and in microdialysate. Increasing brain tyrosine levels had no effect on DA levels in MPFC microdialysate. We conclude that (i) regional differences in the response of dopamine neurons to systemic tyrosine administration cannot be attributed to pharmacokinetic factors; (ii) in vivo microdialysate provides an excellent index over time and across a wide range of tyrosine doses, of brain tissue tyrosine levels; and (iii) increases in brain tyrosine levels do not affect basal DA release in the MPFC.     

Enzymatic hydrolysis of the Eisenia andrei earthworm: Characterization and evaluation of its properties

Some studies have carried out in order to retrieve proteins from the by-product of animal-processing industries. Earthworms are rich in protein and usually are used in animal feed. Thus, this study aimed to optimize the hydrolysis process of Eisenia andrei earthworms by employing Alcalase enzyme. Using the response surface methodology, we evaluated the following conditions: temperature, hydrolysis time, stirring speed, and enzyme/substrate ratio. The optimal conditions for the experimental design were determined through the analysis of the foaming and emulsifying properties, in vitro starch digestibility, and antioxidant activity. The results demonstrate that the highest degree of hydrolysis (i.e., 92%) was obtained under the following conditions: pH, 9.5; temperature, 25?°C; hydrolysis time, 2.25?h; stirring speed, 200?rpm; and enzyme/substrate ratio, 1.77%, using Alcalase enzyme. Evaluation of the amino acid composition under these conditions revealed higher concentrations of aspartic acid, glutamic acid, and leucine. The in vitro protein digestibility of the hydrolysate was approximately 73%. There were no significant improvements in either foam stability or emulsification after enzymatic hydrolysis. Additional studies on the antioxidant activity are required. This bioproduct could potentially serve as a promising supplementary food product.     

Mode and tempo in the evolution of socio-political organization: reconciling 'Darwinian' and 'Spencerian' evolutionary approaches in anthropology

Traditional investigations of the evolution of human social and political institutions trace their ancestry back to nineteenth century social scientists such as Herbert Spencer, and have concentrated on the increase in socio-political complexity over time. More recent studies of cultural evolution have been explicitly informed by Darwinian evolutionary theory and focus on the transmission of cultural traits between individuals. These two approaches to investigating cultural change are often seen as incompatible. However, we argue that many of the defining features and assumptions of 'Spencerian' cultural evolutionary theory represent testable hypotheses that can and should be tackled within a broader 'Darwinian' framework. In this paper we apply phylogenetic comparative techniques to data from Austronesian-speaking societies of Island South-East Asia and the Pacific to test hypotheses about the mode and tempo of human socio-political evolution. We find support for three ideas often associated with Spencerian cultural evolutionary theory: (i) political organization has evolved through a regular sequence of forms, (ii) increases in hierarchical political complexity have been more common than decreases, and (iii) political organization has co-evolved with the wider presence of hereditary social stratification.     

Evolution and development of the chordates: collagen and pharyngeal cartilage

Chordates evolved a unique body plan within deuterostomes and are considered to share five morphological characters, a muscular postanal tail, a notochord, a dorsal neural tube, an endostyle, and pharyngeal gill slits. The phylum Chordata typically includes three subphyla, Cephalochordata, Vertebrata, and Tunicata, the last showing a chordate body plan only as a larva. Hemichordates, in contrast, have pharyngeal gill slits, an endostyle, and a postanal tail but appear to lack a notochord and dorsal neural tube. Because hemichordates are the sister group of echinoderms, the morphological features shared with the chordates must have been present in the deuterostome ancestor. No extant echinoderms share any of the chordate features, so presumably they have lost these structures evolutionarily. We review the development of chordate characters in hemichordates and present new data characterizing the pharyngeal gill slits and their cartilaginous gill bars. We show that hemichordate gill bars contain collagen and proteoglycans but are acellular. Hemichordates and cephalochordates, or lancelets, show strong similarities in their gill bars, suggesting that an acellular cartilage may have preceded cellular cartilage in deuterostomes. Our evidence suggests that the deuterostome ancestor was a benthic worm with gill slits and acellular gill cartilages.     

Expanded Phylogenetic Representation of Genera Opercularia and Epistylis Sheds Light on the Evolution and Higher‐Level Taxonomy of Peritrich Ciliates (Ciliophora: Peritrichia)

ABSTRACT. We have generated 18S rRNA sequences for peritrichs collected in Brazil, including four Opercularia species, two different populations of Epistylis plicatilis (one epibiont and another free‐living), and one additional Epistylis species. Our Opercularia species clustered with the previously available Opercularia microdiscum, corroborating the monophyly of this genus. The Epistylis sampled here clustered with previously sequenced species of this genus. The two populations of E. plicatilis collected in Brazil clustered closely together despite their different ecological contexts, whereas both were very divergent from the sample assigned to the same species previously sampled in China. If affirmed by additional morphological corroboration of species assignment, this observation would indicate that samples from different continents morphologically allocated in the same species may in fact belong to distant evolutionary lineages. More broadly, our results support the recognition of two major clades within Peritrichia. Given the robustness of their support, we suggest that these two clades should be formally recognized as orders, and propose the names Vorticellida and Operculariida to designate them. Furthermore, Epistylis species occurred in both orders, tending to occupy basal positions. This suggests that characters used to define this genus may be plesiomorphic for Peritrichia, so that Epistylis may in fact represent an assemblage of basal species retaining ancestral features.     

Theoretical morphology of colonial meshworks in the Fenestrata (Bryozoa): modelling hydraulic-resistance constraints and minimum fenestrule widths

Ancient fenestrate bryozoans (Fenestellidae, Polyporidae) exhibit a range of fenestrule widths that can be investigated to gain insights about constraints on meshwork morphology. Theoretical morphospace analyses of branch width and spacing reveal that there is a minimum fenestrule width common to both groups. We propose that the minimum fenestrule width observed in fenestrate colonies was constrained by hydraulic resistance (the hydraulic-resistance-constraint hypothesis). Modelling that considers both the viscous and inertial components of fluid-flow resistance through hypothetical fenestrate meshworks corroborates this hypothesis for the smaller fenestrate meshworks of the biserial fenestellids and for polyporids with branch widths less than about 0.6 mm. However, the geometry of the polyporid meshworks in species with branches wider than 0.6 mm does not appear to have been determined by a hydraulic-resistance constraint. Instead, maximum branch densities in the larger-branched polyserial polyporid colonies appear to have been constrained by a limit on the number of zooid rows that these colonies could develop on their branches (the zooid-row-limit hypothesis). The observed decrease in the minimum fenestrule width in these colonies is the indirect geometric result of the inability of the larger polyserial polyporid colonies to develop meshworks with high branch densities.     

Phylogenetic analysis of the loricariid subfamily Hypoptopomatinae (Pisces: Siluroidei: Loricariidae), with comments on generic diagnoses and geographic distribution

A survey of 55 osteological and myological features provided the basis for a phylogenetic analysis of the genera of the loricariid subfamily Hypoptopomatinae. Eleven genera are recognized. Aceslridium, Hypoptopoma, Microlepidogaster, Otocinclus (sensu stricto), Otothyris, Oxyropsis, Par otocinclus, Pseudotocinclus, Schizolecis and an unnamed new genus from Venezuela are each hypothesized as monophyletic on the basis of at least one uniquely derived, unreversed character stale. Pseudotothyris is diagnosed by one character state representing evolutionary convergence. Otocinclus , as presently defined (Isbriicker, 1980), is paraphyletic. Species related to Otocinclus vestitus , the type species, are more closely related to other Hypoptopomatinae than to other Otocinclus species. The hypothesis of generic relationships described herein is based on the consensus among three equally parsimonious trees of length 89 steps (c = 0.652). Distribution of character states on that tree and character-state evolution are discussed in terms of support for each lineage. Thirty-three trees were found one step longer (length = 90, c = 0.644) than the shortest, most parsimonious trees. The consensus among these 33 trees revealed two additional unresolved polychotomies involving members of the tribe Otothyrini and a clade composed of Hypoptopoma, Oxyropsis and Aceslridium. A preliminary framework for the analysis of historical biogeography of the Hypoptopomatinae is discussed.