Clinal variation in carapace shape in the South American freshwater crab,Aegla uruguayana (Anomura: Aeglidae)

South America has been influenced by different geoclimatic events ever since its separation from Africa. The inland water fauna has evolved in response to the changing landscape. Currently, there are indications of variations in populations, occurring to different degrees that would indicate a clinal pattern in morphology. Among South America's fauna, the freshwater anomuran, Aegla, is an enigmatic group as a result of its endemicity and is composed of only one genus. Of all the species in this family, Aegla uruguayana has the broadest distribution. Its native habitats have been influenced by several marine transgressions during the Miocene–Quaternary Periods; thus, it is likely that their current distribution has been more recent. Its habitat spreads across a number of isolated basins and sub‐basins that display distinct degrees of isolation/connection, making clinal variation patterns in the morphology of this species possible. The present study aimed to evaluate the pattern of carapace shape variation in A. uruguayana and how it relates to the isolation and/or connection of populations from different basins and sub‐basins, allowing the determination of any extant clinal patterns. The specimens studied belong to 25 separate populations, representing all areas in which the species currently exists. A total of 523 crabs were analyzed. We identified 13 landmarks and four semi‐landmarks in the carapace. The aeglids were divided into seven size intervals to avoid an allometry effect. In each size category, shape relationships analyzed by principal component analysis suggest a geographical pattern corresponding to the distribution of the populations studied. An evaluation of covariation between body shape and geographical coordinates reveals a strong pattern and shows that population distribution had a significant effect on species morphology. Additionally, according to covariance analysis, the variation in shape was not associated with the environmental variables studied. We observed a clinal pattern throughout the species distribution, which could be attributed to genetic drift. It is possible that this process is being amplified by the geographical isolation of the basins, differences in environmental characteristics, and low dispersal ability. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 914–930.     

Structural analysis of an HLA-B27 population variant, B27f. Multiple patterns of amino acid changes within a single polypeptide segment generate polymorphism in HLA-B27

The structure of a new HLA-B27 variant, B27f, distinguishable from other HLA-B27 subtypes by isoelectric focusing and serologic criteria, has been established by comparative peptide mapping and radiochemical sequence analysis. HLA-B27f differs from the major B27.1 subtype in three clustered amino acid replacements: Asp74, Asp77, and Leu81 in B27.1 are changed to Tyr74, Asn77, and Ala81, respectively in B27f. This pattern of differences is analogous to that of HLA-B27.2 in that this subtype also differs from B27.1 in multiple clustered substitutions within the same segment. Thus, polymorphism within the HLA-B27 system is being achieved by introducing different sets of amino acid changes within a particular short segment of the alpha 1 domain. The most likely mechanism for the introduction of multiple changes within this segment is a nonreciprocal recombination event, such as gene conversion. The structural analogies and ethnic distribution of B27f and B27.2 as compared with those of B27.3, and B27.4 support a dynamic model of HLA-B27 evolution in which polymorphism has been created after the separation of the major ethnic groups. In this model, a Caucasian branch would be characterized by subtypes differing from B27.1 in a few changes within the alpha 1 domain, which were probably generated by single genetic steps. An Oriental branch would include those subtypes which differ from B27.1 by changes in both alpha 1 and alpha 2, involving multiple genetic steps for their generation.     

Studies on evolutionary and selective properties of hypercycles using a Monte Carlo method

Summary The most relevant properties of hypercycles were previously studied mainly from a theoretical point of view. We have developed a Monte Carlo method simulating hypercyclic organization to obtain information about the dynamics of this prebiotic organization. Nucleation, growth, and selective properties have been tested and the results obtained are in good agreement with those of the theoretical predictions. The influence of hypercyclic organization of the error threshold has also been studied. As a consequence of the emergence of a hypercycle, the value of this threshold decreases. The amount of this decrease depends on the population size. Moreover, for some interval of quality factor values, either the hypercycle organization or an error catastrophe can be produced, depending on the initial conditions. The influence of these phenomena on both the dynamic behavior and evolutionary advantages of the hypercycle, as well as their decisive roles on genome size, are discussed.Presented at the FEBS Symposium on Genome Organization and Evolution, held in Crete, Greece, September 1–5, 1986     

Binding of flunitrazepam to differentiating neurons cultured in a chemically defined,hormone-supplemented medium

[³H]Flunitrazepam (FNZ) binding to cortical neurons from fetal rat brain was investigated in vitro. The use of a synthetic medium specific for neurons made it possible to plot a developmental curve of³H-FNZ binding in an almost pure neuronal culture. Detectable specific binding was present in vitro at time 0 (that is, the 16th gestational day). A progressive increase of binding, due to an increment in the number of recognition sites, was observed on the subsequent days. The affinity of the specific binding sites to³H-FNZ was enhanced by the addition of exogenous GABA, whereas the density was not affected.     

Effects of lignin on the anaerobic degradation of (ligno) cellulosic wastes by rumen microorganisms

Summary There appeared to be a clear correlation between the lignin content (% of TS) of several waste and natural materials and their degradability by rumen microorganisms. Materials with lignin contents higher than 25% were not degraded within 72 h. The effects of Kraft pine lignin and some lignin monomers on filter paper degradation, methane production and CMCase activity were tested. Testing these compounds in concentrations comparable to natural conditions showed minor effects. At higher concentrations p-coumaric acid strongly inhibited cellulose degradation and methane production in batch cultures. Influence of lignin compounds on degradation is discussed in relation to structural effects and enzyme or growth inhibition.     

Distribution of polyamines and their related catabolic enzyme in etiolated and light-grown leguminosae seedlings

Diamine-oxidase (DAO; EC 1.4.3.6) activity and di-and polyamine levels were estimated along the epicotyl and root of light-grown and etiolated lentil (Lens culinaris Medicus) and pea (Pisum sativum L.) seedlings. The activity of DAO was higher in etiolated epicotyls than in lightgrown ones. In both species there was a positive correlation between DAO activity and the diamine (putrescine and cadaverine) levels along the whole epicotyl and root. Polyamine (spermine and spermidine) distribution seemed to be associated with the meristematic and elongating zone of the epicotyl and root. The physiological function of DAO is discussed in relation to its possible role in providing hydrogen peroxide to peroxidase-dependent reactions occurring in the cell wall.Abbreviations CAD cadaverine - DA diamine - DAO diamine oxidase - PA polyamine - PUT putrescine - SPD spermidine - SPM spermine     

Effect of long-term n-butanol ingestion on rat brain polypeptide synthesis directed by endogenous messengers.

Long-term ingestion of sublethal n-butanol doses by rats led to a noteworthy increase in the resistance of in vitro brain ribosomal function to the acute inhibitory action of ethanol and isopropanol. Withdrawal of n-butanol did not change this adaptation process immediately. The step affected seems to be the elongation of polypeptide chains. The dependence of in vitro translation on incubation temperature was affected by the adaptation process, the translation system of chronic animals being less stimulatable than that of control animals at low temperature.     

Large cation-selective pores from rat liver peroxisomal membranes incorporated to planar lipid bilayers

Summary Fusion of a highly purified fraction of rat liver peroxisomal membranes to planar lipid bilayers incorporates large, cation-selective voltage-dependent pores. TheP _K/P _Cl ratio of these pores, estimated in KCl gradients, is close to 4. The pores display several conductance states and spend most of the time open at voltages near 0 mV, closing at more positive and negative voltages. At voltages near 0 mV the most frequent open state has a conductance of 2.4 nS in 0.3m KCl. At voltages more positive and more negative than 10 mV the most frequent open state displays a conductance of 1.2 nS in 0.3m KCl. With these results pore diameters of 3 and 1.5 nm, respectively, can be estimated. We suggest that these pores might account for the unusually high permeability of peroxisomes to low molecular weight solutes. Fusion also incorporates a perfectly anion-selective, two-open states channel with conductances of 50 and 100 pS in 0.1m KCl.     

Balance between anionic and cationic extracellular peroxidase activities in Sedum album leaves after ozone exposure. Analysis by high-performance liquid chromatography

Peroxidase activity was assayed with different electron donors (guaiacol, ascorbate, syringaldazine) in the intercellular fluid of Sedum album L. leaves after ozone exposure. Anionic and cationic peroxidases were separated and purified by high performance ion-exchange and gel permeation chromatography. Both isoperoxidases were tested as regards their molecular weight and apparent kinetic constants with different substrates. Ascorbate peroxidase activity was rapidly stimulated after ozone exposure, whereas syringaldazine peroxidase activity reached its maximum 24 h later. Increases in ascorbate and syringaldazine peroxidase activities occurred simultaneously with increases in cationic and anionic peroxidase activities, respectively. Apparent K_m values indicate a high affinity of cationic peroxidases for ascorbate and of anionic peroxidases for syringaldazine. The metabolic role of this balance between cationic and anionic peroxidases after ozone exposure is discussed.     

Occurrence of diamine oxidase in the apoplast of pea epicotyls

Most of the diamine oxidase (EC 1.4.3.6) present in pea (Pisum sativum L. cv. Rondo) epicotyls is found in the fluid obtained by centrifuging pea epicotyl sections previously infiltrated under vacuum with a buffer solution. No detectable amount of the cytoplasmic enzyme glucose-6-phosphate dehydrogenase is present in this fluid, showing that there is very little contamination by cell contents. Polyacrylamide-gel electrophoresis and specific-activity data indicate that diamine oxidase is the most plentiful protein in the extracellular solution obtained from pea epicotyl sections and that an active process is involved in the selective transfer of the enzyme outside the cell. The possible involvement of diamine oxidase in the supply of H₂O₂ to peroxidase-catalyzed reactions occurring inside the cell wall is discussed.Abbreviations DAO diamine oxidase - Glc6P glucose-6-phosphate