Photoreceptors for biosynthesis, energy storage and vision

Abstract Living organisms use light as a source of energy and as a means of obtaining information about their environment. Photoreactivating enzyme, provitamins D, retinal (rhodopsins and bacteriorhodopsin), porphyrins (chlorophyll, protochlorophyll and heme), photosynthetic accessory pigments (carotenoids and bilins), phytochrome and riboflavin: these are the molecules which life has settled upon to play the role of light receptor. For some of these photoreceptor molecules a great deal is now known about the chemistry which they perform upon absorbing light; for others virtually nothing is known. Riboflavin, the molecule believed to be functioning in a variety of organisms as the receptor for physiological responses to blue light, is an especially interesting case. Its widespread occurrence in cellular roles other than photoreception make it difficult to separate out the particular flavin which functions as the photoreceptor. It represents a case of a photoreceptor which is at once ubiquitous and elusive.     

Screening for antiproliferative activity of six southern Brazilian species of Hypericum

The crude methanolic extracts of six species of Hypericum growing in southern Brazil (Hypericum caprifoliatum Cham. & Schlecht., H. carinatum Griseb., H. connatum Lam., H. myrianthum Cham. & Schlecht., H. polyanthemum Klotzsch ex Reichardt and H. ternum A. St. Hil.) were screened for their antiproliferative activity against two cell lines (HT-29 human colon carcinoma cells and H-460 non-small cell lung carcinoma). The most active crude extracts were those from H. caprifoliatum, H. myrianthum and, to a lesser extent, from H. connatum. All plants were submitted to fractionation with solvents in increasing polarity and re-assayed for the two cell lines used previously, as well as U-373 human malignant glioma cells. The most active fractions were the hexane fractions obtained from H. caprifoliatum, H. myrianthum and H. ternum.     

Microsatellite markers for Ceiba pentandra (Bombacaceae), an endangered tree species of the Amazon forest

From a genomic library enriched for AG/TC repeats, eight polymorphic microsatellite markers were developed for Ceiba pentandra, a pan‐tropical forest tree. Polymorphism was evaluated using a panel of 74 adult trees. Using automated fluorescence detection, a total of 112 alleles was detected with an average of 14 alleles per locus. All microsatellite loci showed very high levels of genetic information content, with expected heterozygosity ranging from 0.814 to 0.895. These microsatellite markers represent a powerful tool to investigate refined questions of mating systems, gene flow, family structure and population dynamics in natural populations of C. pentandra.     

Homology of the genital sclerites of Megaloptera (Insecta: Neuropterida) and their phylogenetic relevance

The genitalia of Megaloptera are crucial for taxonomic identification and represent a significant component of characters for phylogenetic interpretation of this order. However, several complex genital structures, especially those related to segments 9 and 11 in Megaloptera, have yet to be subjected to a comprehensive survey of homology. The terminology for genital sclerites has been variously and even incorrectly used by different authors, a fact which could lead to much confusion about character evolution. In this paper, we first present a comprehensive morphological comparison of the sclerites of male and female genital segments in 23 megalopteran genera representing all major lineages of Corydalinae, Chauliodinae and Sialidae. Accordingly, we then provide new interpretations on the homology of the genital sclerites which often appear to be considerably different among Megaloptera. Based on our new and revised homology assessments, we conclude that: (i) the small to medium‐sized sclerite beneath the ectoprocts in males of Sialidae represents the fused gonocoxites 11; (ii) the male gonocoxites 11 in Corydalidae are largely reduced and are sometimes retained as a small sclerite beneath the anus; (iii) the predominant sternite‐like sclerite of the female abdominal segment 8 represents the fused gonocoxites 8; and (iv) a pair of sclerites amalgamated with the lateral arms of male gonocoxites 10 in Chauliodinae is the gonocoxites 9. Furthermore, based on our genital homology assessments, we reconstruct an intergeneric phylogeny including all genera of Megaloptera using genital characters in a parsimonious analysis to test their phylogenetic relevance. The phylogeny herein recovered is largely congruent with the results from several previous studies, thus underlying the significant phylogenetic relevance of the megalopteran genital sclerites. The present work provides new insights into the evolution of insect genitalia.     

Genetic Structure of Wild Rice Oryza Glumaepatula Populations in Three Brazilian Biomes Using Microsatellite Markers

The existence of Oryza glumaepatula is threatened by devastation and, thus, the implementation of conservation strategies is extremely relevant. This study aimed to characterize the genetic variability and estimate population parameters of 30 O. glumaepatula populations from three Brazilian biomes using 10 microsatellite markers. The levels of allelic variability for the SSR loci presented a mean of 10.3 alleles per locus and a value of 0.10 for the average allelic frequency value. The expected total heterozygosity (H_e) ranged from 0.63 to 0.86. For the 30 populations tested, the mean observed (H_o) and expected heterozygosities (H_e) were 0.03 and 0.11within population, respectively, indicating an excess of homozygotes resulting from the preferentially self-pollinating reproduction habit. The estimated fixation index ( _IS ) was 0.79 that differed significantly from zero, indicating high inbreeding within each O. glumaepatula population. The total inbreeding of the species (_IT ) was 0.98 and the genetic diversity indexes among populations, _ST and _ST, were 0.85 and 0.90, respectively, indicating high genetic variability among them. Thus, especially for populations located in regions threatened with devastation, it is urgent that in situ preservation conditions should be created or that collections be made for ex situ preservation to prevent loss of the species genetic variability.     

Ultrasonographic assessment of skeletal muscles after experimentally induced neurogenic inflammation (facet injury) in rats

This study set out to examine ultrasonographic attributes of non-neurosegmentally (pectoral-forelimb) and neurosegmentally linked (hindlimb) myotomes in an experimental model that leads to neurogenic inflammation in segmentally linked myotomes, and to evaluate quantitative correlations among ultrasonographic attributes of the muscles, relative content of various inflammatory mediators, and nociceptive thresholds (hot and mechanical) in rats. Twelve male Wistar Kyoto rats were randomly divided into two equinumerous groups: surgery group, in which the left lumbar (L4–L6) facet joints were compressed for 3 min with modified Kelly forceps under general anesthesia, and sham-operated rats. All ultrasonograms were obtained with the Vevo 2100 Visual Sonic scanner connected to a 24-MHz transducer at four different time points: pre-surgery and 7, 14, and 21 days after surgical procedures. Digital ultrasonographic images of quadriceps femoris, hamstring, and pectoral-brachial muscle groups were analyzed using a polygonal meter region of interest placed on the largest cross-sectional area of the muscles displayed in Image ProPlus^® analytical software to compute numerical pixel values and pixel heterogeneity (standard deviation of mean pixel values). On day 21, pain behavior tests (hot plate and von Frey) were performed and then all animals were euthanized. Protein expression of inflammatory mediators in biceps brachii and rectus femoris muscles was measured by Western blot. The most prominent differences in muscle echotextural attributes between the two subsets of rats occurred 14 days post-surgery in pectoral-brachial and quadriceps femoris muscles. The expression of calcitonin-gene-related peptide was directly related to both echotextural variables only in biceps brachii (pixel intensity: r = 0.65, P = 0.02; and heterogeneity: r = 0.66, P = 0.02, respectively). Our findings have revealed the occurrence of echotextural changes in skeletal muscles of rats during myositis; however, the accumulation of inflammatory mediators and the outcomes of sensory tests did not relate to the changes in first-order echotextural characteristics of affected hindlimb muscles.     

The larval head of Nevrorthidae and the phylogeny of Neuroptera (Insecta)

External and internal head structures of larvae of Nevrorthidae were described in detail. The results were compared to conditions found in other representatives of Neuroptera and the other two neuropterid orders. The cladistic analysis supported the monophyly of Neuroptera, Neuroptera exclusive of Nevrorthidae, Hemerobiiformia, and Myrmeleontiformia. Neuroptera exclusive of Nevrorthidae are supported by the formation of an undivided postmentum and the presence of cryptonephric Malpighian tubules. The highly specialized articulation of the neck (Rollengelenk) and the absence of a salivary duct are autapomorphies of Nevrorthidae. Ithonidae and Polystoechotidae form a clade and are the sister group of the remaining Hemerobiiformia, which are characterized by the complete lack of a gula and a terminal filament of the antenna. Within this lineage, a clade comprising Mantispidae, Dilaridae, Berothidae, and Rhachiberothidae is well supported. Larvae of Myrmeleontiformia are characterized by a complex transformation of head structures, with a hypostomal bridge, a small triangular gula, largely reduced maxillary grooves, and anteriorly shifted posterior tentorial grooves. The slender finger‐like mid‐dorsal apodeme is another autapomorphy of the group. Psychopsidae are placed as the sister group of the remaining Myrmeleontiformia, which are characterized by a conspicuous, protruding ocular region (often less distinct or even absent in Nemopteridae). Ascalaphidae are the sister group of Myrmeleontidae. Larvae of both families share the fusion of the tibia and tarsus in the hind leg. The larval characters analysed were not sufficient for full resolution of the myrmeleontiform and hemerobiiform lineages. The position of several families such as Osmylidae, Sisyridae, and Coniopterygidae remains uncertain. The results are in agreement with an aquatic ancestor of Neuroptera and secondarily acquired terrestrial habits within the lineage (Neuroptera exclusive of Nevrorthidae), and another invasion of the aquatic environment by Sisyridae. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 533–562.     

Homocysteine contribution to DNA damage in cystathionine β-synthase-deficient patients

High blood levels of homocysteine (Hcy) are found in patients affected by homocystinuria, a genetic disorder caused by deficiency of cystathionine β-synthase (CBS) activity, as well as in nutritional deficiencies (vitamin B₁₂ or folate) and in abnormal renal function. We previously demonstrated that lipid and protein oxidative damage is increased and the antioxidant defenses diminished in plasma of CBS-deficient patients, indicating that oxidative stress is involved in the pathophysiology of this disease. In the present work, we extended these investigations by evaluating DNA damage through the comet assay in peripheral leukocytes from CBS-deficient patients, as well as by analyzing of the in vitro effect of Hcy on DNA damage in white blood cells. We verified that DNA damage was significantly higher in the CBS-deficient patients under treatment based on a protein-restricted diet and pyridoxine, folic acid, betaine and vitamin B₁₂ supplementation, when compared to controls. Furthermore, the in vitro study showed a concentration-dependent effect of Hcy inducing DNA damage. Taken together, the present data indicate that DNA damage occurs in treated CBS-deficient patients, possibly due to high Hcy levels.     

Characterization of Two Sibling Species of the Genus Stylonychia (Ciliata,Hypotricha): S. mytilus Ehrenberg, 1838 and S. lemnae n. sp. II. Biochemical Characterization1

The two closely related hypotrichous ciliate species, Stylonychia lemnae and S. mytilus, have been compared with respect to their isoenzyme patterns, their macronuclear DNA banding patterns, and micronuclear DNA banding patterns after restriction enzyme digestion. Since macronuclear DNA contains mainly protein-coding sequences and since the micronuclear DNA patterns represent mainly the repetitive fraction of the genome, these results, together with the isoenzyme patterns, reflect differences on three different levels of molecular evolution between morphologically very similar species. Each of the three methods allows an unequivocal identification of each of the two species. Intraspecific variation seems to be greatest among the repetitive sequences of the micronuclear genomes. By using the isoenzyme data and the formula of Nei (19) the genetic distance between the two species is calculated and compared with the results from other protozoa and different Drosophila species. Despite their morphological similarity, the two species show a considerable amount of evolutionary divergence on the three molecular levels which have been investigated.