Evolutionary origins of Brassicaceae specific genes in Arabidopsis thaliana

Background  

All sequenced genomes contain a proportion of lineage-specific genes, which exhibit no sequence similarity to any genes outside the lineage. Despite their prevalence, the origins and functions of most lineage-specific genes remain largely unknown. As more genomes are sequenced opportunities for understanding evolutionary origins and functions of lineage-specific genes are increasing.     

P-glycoprotein activity in human Caucasian male lymphocytes does not follow its increased expression during aging

P-glycoprotein (P-gp) is a transmembrane protein that mediates the efflux of innumerous structurally unrelated compounds. It was initially found over-expressed in tumor cells, associated to a multidrug resistance phenotype (MDR). Then, P-gp was found constitutively expressed in excretory cells/tissues and in circulating cells, such as lymphocytes. Considering the importance of this transporter in the establishment of therapeutic protocols and the existence of contradictory results, this study aimed at evaluating the influence of aging in the expression and function of P-gp in human lymphocytes, comparing two different methodologies to assess both parameters. P-gp activity and expression were evaluated in lymphocytes isolated from whole blood samples of 65 healthy caucasian male donors, divided into two groups according to age (group 1: under 30-years old; group 2: above 60-years old). P-gp expression was assessed using the anti-P-gp monoclonal antibody, UIC2, in the presence and in absence of vinblastine (Vbl). P-gp activity was evaluated measuring the efflux rate of the fluorescent P-gp substrate rhodamine 123 (Rho 123) and also using UIC2 shift assay. Flow cytometric analysis was performed to assess all the proceedings. Furthermore, P-gp expression and each of the P-gp activity determination methods were compared, through correlation analysis and linear regression models. We observed a significant age-dependent increase in mean P-gp expression (p = 0.029), which was not reflected in the transporter's activity (p > 0.050). Statistical analysis allowed selection of UIC2 shift assay over Rho 123 efflux assay as a more selective method to assess P-gp activity. Despite the significant correlation between P-gp expression and P-gp activity found in lymphocytes (Gp1(group 1)-r = 0.609, p < 0.001; Gp2-r = 0.461, p = 0.012), using UIC2 shift assay, these data reinforce the need for P-gp activity assessment, rather than P-gp expression determination alone, when starting new therapeutic regimens with P-gp substrates, especially in men older than 60 years of age.     

Production of laccases in submerged process by <Emphasis Type="Italic">Pleurotus sajor-caju</Emphasis> PS-2001 in relation to carbon and organic nitrogen sources,antifoams and Tween 80

Some conditions in media composition for laccases production, such as different sources of carbon and organic nitrogen, antifoams and a surfactant, were studied in liquid cultures of Pleurotus sajor-caju strain PS-2001. Cultivation with fructose or glucose as carbon sources produced maximum enzyme activities of 37 and 36 U mL⁻¹, respectively. When sucrose was present in the medium, the best results were obtained using 5 g L⁻¹ of this carbohydrate, on the 11th day of the process, attaining laccase titres of 13 U mL⁻¹. In a medium without casein, practically no enzyme was produced during the experiments; among the sources of nitrogen studied, pure casein led to the highest titres of laccase activity. Different concentrations of pure casein and sucrose were also tested. As to the different concentrations of casein, the addition of 1.5 g L⁻¹ resulted in the highest titres of laccase activity. Negligible levels of manganese peroxidase activity were also detected in the culture medium. In low concentrations, polypropylene glycol or silicon-based antifoams and the surfactant Tween 80 have no significant influence on the formation of laccases by P. sajor-caju. However, enhanced concentration of polypropylene glycol negatively affected the production of laccases but favored the titres in total peroxidases, lignin peroxidase and veratryl alcohol oxidase.     

Study of gelling behavior of poly(vinyl alcohol)-methacrylate for potential utilizations in tissue replacement and drug delivery

The need of innovative, multifunctional biomaterials for the partial or complete tissue replacement is the driving force for the search of improvements of the performances of the available materials and in the formulation of new ones. Addressing the focus to vitreous substitution, we have explored the possibility of using injectable aqueous solutions of poly(vinyl alcohol), PVA, derivatives able to form hydrogels in the ocular cavity upon UV-vis irradiation with visible light. In particular, we describe the features of hydrogels from methacrylate grafted PVA, PVA-MA, in terms of structural characteristics, degradation processes, release of low- and high- molecular weight molecules, and in vitro gelation kinetics. The mechanical properties, drug delivery tests, and rheology tests suggest that PVA-MA derivatives have the potential to become a useful material for vitreous substitution.     

The synthesis of short- and medium-chain-length poly(hydroxyalkanoate) mixtures from glucose- or alkanoic acid-grown <Emphasis Type="Italic">Pseudomonas oleovorans</Emphasis>

Pseudomonas oleovorans NRRL B-778 accumulated mixtures of poly-3-hydroxybutyrate (PHB) and medium-chain-length poly(hydroxyalkanoates) (mcl-PHAs) when grown on glucose, octanoic acid or oleic acid, whereas growth on nonanoic acid or undecanoic acid resulted in copolymers of poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHB-co-HV). Acetone fractionation verified the presence of PHB/mcl-PHA mixtures. The acetone-insoluble (AIS) fractions of the polymers derived from glucose (PHA-glucose), octanoic acid (PHA-octanoic) and oleic acid (PHA-oleic) were exclusively PHB while the acetone-soluble (AS) fractions contained mcl-PHA composed of differing ratios of 3-hydroxy-acid monomer units, which ranged in chain length from 6 to 14 carbon atoms. In contrast, both the AIS and AS fractions from the polymers derived from nonanoic acid (PHA-nonanoic) and undecanoic acid (PHA-undecanoic) were composed of comparable ratios of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV). The unfractionated PHA-glucose, PHA-octanoic and PHA-oleic polymers had melting temperatures (T _m) between 177 and 179°C, enthalpies of fusion (ΔH _f) of 20 cal/g and glass transition temperatures (T _g) of 3–4°C. This was due to the large PHB content in the polymer mixtures. On the other hand, the PHA-nonanoic and PHA-undecanoic polymers had thermal properties that supported their copolymer nature. In both cases, the T _m values were 161°C, ΔH _f values were 7cal/g and T _g values were −3°C. Journal of Industrial Microbiology & Biotechnology (2002) 28, 147–153 DOI: 10.1038/sj/jim/7000231 Received 30 July 2001/ Accepted in revised form 04 November 2001     

Evolution of anaerobic ciliates from the gastrointestinal tract: phylogenetic analysis of the ribosomal repeat from Nyctotherus ovalis and its relatives

The 18S and 5.8S rDNA genes and the internal transcribed spacers ITS-1 and ITS-2 of ciliates living in the hindgut of frogs, millipedes, and cockroaches were analyzed in order to study the evolution of intestinal protists. All ciliates studied here belong to the genus Nycrotherus. Phylogenetic analysis revealed that these ciliates from a monophyletic group that includes the distantly related anaerobic free-living heterotrichous ciliates Metopus palaeformis and Metopus contortus. The intestinal ciliates from the different vertebrate and invertebrate hosts are clearly divergent at the level of their rDNA repeats. This argues for the antiquity of the associations and a predominantly vertical transmission. This mode of transmission seems to be controlled primarily by the behavior of the host. The different degrees of divergence between ciliates living in different strains of one and the same cockroach species most likely reflect the different geographical origins of the hosts. In addition, host switches must have occurred during the evolution of cockroaches, since identical ciliates were found only in distantly related hosts. These phenomena prevent the reconstruction of potential cospeciation events.      

我国巴拉巴按蚊形态描述

白踝按蚊种团是由很多形态近似的蚊种组成,其中巴拉巴按蚊和白踝按蚊均为东南亚一带的重要传疟媒介。我国过去资料均记载为白踝按蚊,但未从形态上详细鉴定。为了确定该种的分类地位,1963年作者等在海南岛万宁县兴隆附近山林区采集“白踝按蚊”全套标本10批共150多套,1971年后从云南省采集少数标本进行形态鉴定,发现其与Colless(1956,1957)所描述的白踝按蚊Anopheles leucosphyrus leucosphyrus Donitz(1901)有很明显的差别,而与巴拉巴按蚊A.balabacensis balabacensis Balsas(1936)除某些特征略有差异外,余均完全一致。按Colless的分类法,过去我国记载的“白踝按蚊”,应鉴定为巴拉巴按蚊A.balabacensis balabacensis Baisas。     

Evidence for Circadian Variations of Thyroid Hormone Concentrations and Type II 5'-Iodothyronine Deiodinase Activity in the Rat Central Nervous System

Abstract: The 24-h patterns of tissue thyroid hormone concentrations and type II 5'- and type III 5-iodothyronine deiodinase (5'D-II and 5D-III, respectively) activities were determined at 4-h intervals in different brain regions of male euthyroid rats entrained to a regular 12-h light/12-h dark cycle (lights on at 6:00 a.m.). Activity of 5'D-II, which catalyzes the intracellular conversion of thyroxine (T₄) to 3,3',5-triiodo- l -thyronine (T₃) in the CNS, and the tissue concentrations of both T₄ and T₃ exhibited significant daily variations in all brain regions examined. Periodic regression analysis revealed significant circadian rhythms with amplitudes ranging from 9 to 23% (for T₃) and from 15 to 40% (for T₄ and 5'D-II) of the daily mean value. 5'D-II activity showed a marked nocturnal increase (1.3–2.1-fold vs. daytime basal value), with a maximum at the end of the dark period and a minimum between noon and 4:00 p.m. 5D-III did not exhibit circadian patterns of variation in any of the brain tissues investigated. Our results disclose circadian rhythms of 5'D-II activity and thyroid hormone concentrations in discrete brain regions of rats entrained to a regular 12:12-h light-dark cycle and reveal that, in the rat CNS, T₃ biosynthesis is activated during the dark phase of the photoperiod. For all parameters under investigation, the patterns of variation observed were in part regionally specific, indicating that different regulatory mechanisms may be involved in generating the observed rhythms.