Reconstitution into liposomes of the B°-like glutamine-neutral amino acid transporter from renal cell plasma membrane

Na⁺ dependent [³H]glutamine uptake was found in liposomes reconstituted with solubilized rat kidney brush border in the presence of intraliposomal K⁺. The reconstituted system was optimised with respect to the critical parameters of the cyclic detergent removal procedure, i.e., the detergent used for the solubilization, the protein concentration, the detergent/phospholipid ratio and the number of passages through a single Amberlite column. Time dependent [³H]glutamine accumulation in proteoliposomes occurred only in the presence of external Na⁺and internal K⁺. The transporter showed low if there is any tolerance towards the substitution of Na⁺ or K⁺ for other cations. Valinomycin strongly stimulated the transport indicating that it is electrogenic. Intraliposomal glutamine had no effect. From the dependence of the transport rate on the Na⁺ concentration cooperativity index close to 1 was derived, indicating that 1 Na⁺ should be involved in the cotransport with glutamine. The electrogenicity of the transport originated from the Na⁺ transport. Optimal rate of 0.1 mM [³H]glutamine uptake was found in the presence of 50 mM intraliposomal K-gluconate. At higher K-gluconate concentrations the transport rate decreased. The activity of the reconstituted transporter was pH dependent with optimal function in the range pH 6.5-7.0. [³H]glutamine (and [³H]leucine) uptake was inhibited by all the neutral but not by the positively or negatively charged amino acids. The sulfhydryl reagents HgCl₂, mersalyl, p-hydroxymercuribenzoate and the substrate analogue 2-aminobicyclo[2,2,1]heptane-2-carboxylate strongly inhibited the transporter, whereas the amino acid analogue α-(methylamino)isobutyrate had no effect. The inhibition by mersalyl was protected by the presence of the substrate. On the basis of the Na⁺ dependence, the electrogenic transport mode and the specificity towards the amino acids, the reconstituted transporter was classified as B°-like.     

Linkage of the β-Like ω-Globin Gene to α-Like Globin Genes in an Australian Marsupial Supports the Chromosome Duplication Model for Separation of Globin Gene Clusters

The structure, function, and evolutionary history of globin genes have been the subject of extensive investigation over a period of more than 40 years, yet new globin genes with highly specialized functions are still being discovered and much remains uncertain about their evolutionary history. Here we investigate the molecular evolution of the -globin gene family in a marsupial species, the tammar wallaby, Macropus eugenii. We report the complete DNA sequences of two -like globin genes and show by phylogenetic analyses that one of these genes is orthologous to embryonically expressed -globin genes of marsupials and eutherians and the other is orthologous to adult expressed -globin genes of marsupials and eutherians. We show that the tammar wallaby contains a third functional -like globin gene, -globin, which forms part of the -globin gene cluster. The position of -globin on the 3 side of the -globin cluster and its ancient phylogenetic history fit the criteria, originally proposed by Jeffreys et al. (1980), of a fossil -globin gene and suggest that an ancient chromosome or genome duplication preceded the evolution of unlinked clusters of - and -globin genes in mammals and avians. In eutherian mammals, such as humans and mice, -globin has been silenced or translocated away from the -globin locus, while in marsupials -globin is coordinately expressed with the adult -globin gene just prior to birth to produce a functional hemoglobin (_{2 2}).     

Effect of light intensity on pigments and main acyl lipids during ‘natural’ chloroplast development in wheat seedlings

The content and composition of pigments and acyl lipids (monogalactosyl diacylglycerol, digalactosyl diacylglycerol and phosphatidyl glycerol) have been investigated in developing chloroplasts isolated from successive 2-cm sections along the leaves of wheat seedlings grown either under 100, 30 or 3 W·m^-2. In all examined stages of plastid development chlorophyll a/b and chlorophyll/carotenoid ratios were higher with increasing irradiance, whereas chlorophyll content expressed on fresh weight basis gradually decreased.Concentrations of monogalactosyl diacylglycerol, digalactosyl diacylglycerol and phosphatidyl glycerol decreased per chlorophyll unit with increasing plastid maturity. The higher was the light intensity applied during plant growth, the higher were galactolipid and phosphatidyl glycerol contents in developing chloroplasts. During plastid development the percentage of -linolenic acid markedly increased in total and individual acyl lipids. Under high light conditions, the accumulation of this fatty acid proceeded more rapidly. Significantly higher proportion of -linolenic acid was found in acyl lipid fraction of chloroplasts differentiating in high light grown plants, than in those from plants exposed to lower light intensities. The differences in the double bond index may indicate higher fluidity of thylakoid membranes in sun-type chloroplasts.Trans-3-hexadecenoic acid, virtually absent in the youngest plastids, was found in much higher concentration (per chlorophyll unit and as mol % of phosphatidyl glycerol fatty acids) in chloroplasts developing at high light conditions.Abbreviations MGDG monogalactosyl diacylglycerol - DGDG digalactosyl diacylglycerol - PG phosphatidyl glycerol - PC phosphatidyl choline - DBI double bond index - PS I photosystem I - PS II photosystem II - PSU photosynthetic unit - LHCP light harvesting chlorophyll-protein complex     

Partitioning of resources: the evolutionary genetics of sexual conflict over resource acquisition and allocation

Fitness depends on both the resources that individuals acquire and the allocation of those resources to traits that influence survival and reproduction. Optimal resource allocation differs between females and males as a consequence of their fundamentally different reproductive strategies. However, because most traits have a common genetic basis between the sexes, conflicting selection between the sexes over resource allocation can constrain the evolution of optimal allocation within each sex, and generate trade‐offs for fitness between them (i.e. ‘sexual antagonism’ or ‘intralocus sexual conflict’). The theory of resource acquisition and allocation provides an influential framework for linking genetic variation in acquisition and allocation to empirical evidence of trade‐offs between distinct life‐history traits. However, these models have not considered the emergence of trade‐offs within the context of sexual dimorphism, where they are expected to be particularly common. Here, we extend acquisition–allocation theory and develop a quantitative genetic framework for predicting genetically based trade‐offs between life‐history traits within sexes and between female and male fitness. Our models demonstrate that empirically measurable evidence of sexually antagonistic fitness variation should depend upon three interacting factors that may vary between populations: (1) the genetic variances and between‐sex covariances for resource acquisition and allocation traits, (2) condition‐dependent expression of resource allocation traits and (3) sex differences in selection on the allocation of resource to different fitness components.     

Betaine-homocysteine methyltransferase in the fungus Aspergillus nidulans.

A betaine:homocysteine methyltransferase activity was demonstrated in the cell-free extracts from the fungus $\text{Aspergillus}\text{nidulans}$. Among methionine-requiring mutants which do not grow on homocysteine one class responds to betaine indicating that this compound can serve as a methyl donor in methionine synthesis $\text{in vivo}$. Mutants of the second class which grow only on methionine were shown to have betaine: homocysteine — and methyltetrahydrofolate: homocysteine methyltransferases simultaneously impaired.     

Characterization of a plasma factor having opiate and immunoactivity like beta-endorphin.

A factor from human plasma having opiate-like activity was characterized in the present study. In addition to its ability to inhibit the binding of [³H]-methionine-enkephalin to opiate receptors, it also cross-reacted with two β-endorphin specific anti-sera. Compared with β-endorphin, the plasma factor had a shorter action on inhibiting the contraction of the guinea pig ileum. By gel-filtration chromatography, the size of this factor was intermediate between that of β-endorphin and methionine-enkephalin.     

The costs of sex in seaweeds

The brown seaweeds (Fucales) include dioecious and hermaphrodite species and genera with one, two, tour or eight eggs per oogonium. The costs of gamete production, measured as biomass, are very small. Eggs represent only 0.1–0.4% of body weight. Females of dioecious species do not produce more eggs per gramme of tissue than hermaphrodites. Hermaphrodites occupy upper shore zones and dioecious species the biotically richer submerged zones. Neither egg size nor number correlate with habitat or sexuality. Some of these observations are hard to reconcile with theoretical concepts of the costs of sex.     

Neuroimmune dysfunction in frontotemporal dementia: Insights from progranulin and C9orf72 deficiency

Neuroimmune dysfunction is a cardinal feature of neurodegenerative diseases. But how immune dysregulation in the brain and peripheral organs contribute to neurodegeneration remains unclear. Here, we discuss the recent advances highlighting neuroimmune dysfunction as a key disease-driving factor in frontotemporal dementia (FTD). We provide an overview of the clinical observations supporting a high prevalence of autoimmune diseases in FTD patients with mutations in GRN or C9orf72. We then focus on a myriad of evidence from human genetic studies, mouse models, in vitro assays, and multi-omics platform, which indicate that haploinsufficiency in GRN and C9orf72 promotes neuroimmune dysfunction and contributes to neurodegeneration and premature death. These compelling data provide key insights to disease mechanisms, biomarker discovery, and therapeutic interventions for FTD (120 words).     

Fire fly luciferin as antioxidant and light emitter: the evolution of insect bioluminescence.

Insects are the main group with luminescent species among terrestrial animals. In this paper, we report that fire fly luciferin is endowed with antioxidant properties against oxidative and nitrosative stress. The luciferin reduces linoleate peroxidation in acellular tests and increases the viability of mammalian cells exposed to the oxidant tert-butyl hydroperoxide. Dehydrorhodamine-based tests indicate that fire fly luciferin also scavenges peroxynitrite, whereas parallel tests on cells showed a marked protection of cells subjected to the peroxynitrite generator SIN-1. Together, these results suggest that fire fly luciferin's antioxidant properties could help photocytes coping with the hyperoxidant conditions to which they are submitted during luminous emissions. These data could also suggest that the evolutionary foundation of the bioluminescent system could have been the luciferin, and not the luciferase, first serving as a scavenger of oxidants toxic to the cells, then as a light emitting substrate for luciferase precursors. Similarities with the evolutionary scenario proposed for marine bioluminescent organisms relying on coelenterazine suggest that the surprisingly high success rate observed in the independent emergence of bioluminescent animals could reflect the ease of transformation of antioxidant mechanisms into light-producing systems.