Paropsocolis, a new pentatomid genus with two new species from Brazil (Heteroptera, Pentatomidae, Ochlerini)

When examining specimens of the Janeirona Distant, 1911 clade of Ochlerini (Discocephalinae) we found males and females of two undescribed species. Though clearly similar to the genera in the Janeirona clade, these two species lack the diagnostic characteristics of any of them. We made a cladistic analysis to verify the placement of the two new species in Discocephalinae. A total of 38 taxa and 60 morphological characters were included in the analysis. Character polarization followed the outgroup comparison method, and the most parsimonious trees were calculated in TNT using an implied weighting approach. The analysis resulted in one most parsimonious tree where the two new species form a monophyletic group within the Ochlerini, sister to Janeirona. We propose Paropsocolis Sampaio & Campos, gen. nov. for the two new species Paropsocolis convergens Sampaio & Campos, sp. nov. and Paropsocolis divergens Sampaio & Campos, sp. nov.. The new genus is recognized by having an inconspicuous labial intercalary segment, metasternum anteriorly carinated, parameres with a basal dish-shaped process and a bifurcated apex, theca with one apical ventral process, endosoma with one dorsal and one ventral processes, laterotergites IX surpassing the mediotergite VIII, and thickening of vaginal intima circular. P. convergens Sampaio & Campos, sp. nov. and P. divergens Sampaio & Campos, sp. nov. are described to Brazil. A distributional map is provided.

Determinants of cervical spine disorders in military pilots: a systematic review

BACKGROUND

Neck pain and cervical spine disorders are widespread among military cockpit aircrew pilots and are often recognized as occupational stressors.

AIMS

This systematic review aimed to identify significant determinants for military pilot neck pain and cervical spine disorders determined through multivariable logistic regression studies.

METHODS

This systematic review was conducted according to the recommendations of the Statement of Systematic Review and Meta-analysis Protocols (Preferred Reporting Items for Systematic Reviews and Meta-Analyses [PRISMA]-P). The following databases were searched for literature: Medline and Embase. We included studies that studied neck pain, cervical spine disorders, and/or radiological abnormalities and associated exposures (adjusted odds ratios, ORadj) in military cockpit aircrew. The trustworthiness, relevance and results of the published papers were evaluated using the Joanna Briggs Institute critical checklist.

RESULTS

A total of three studies quantified the strength of the correlations between exposures and outcomes. Significant determinants/risk factors of neck pain, cervical spine disorders and radiological abnormalities were identified as age (ORadj: 1.092 [95% CI 1.054, 1.132]), fighter type (ORadj: 3.9 [95% CI 1.1, 13.9]) and absolute rotation angle of C2-7 (ARA) (ORadj: 0.91 [CI 0.85, 0.98]). The following variables were unable to demonstrate statistical significance: flying hours, body height and body mass index.

CONCLUSIONS

Military cockpit aircrew's frequent neck pain after a flight raises concerns about cervical spine disorders. Age, fighter type and ARA C2-7 are strong predictors of neck pain and cervical spine disorders. More research is needed on occupational determinants and risk factors for neck pain and cervical spine disorders in military cockpit aircrew.

Revision of Heteroscelis Latreille, 1829 (Heteroptera: Pentatomidae: Asopinae) with the description of a new species from Colombia

The Asopinae comprises about 300 species and 63 genera of predatory stinkbugs, of which around 100 species and 23 genera occur in the Neotropical region. The species of the Neotropical genus Heteroscelis Latreille, 1829 are easily recognized by the small size, vivid and often iridescent colors, the elongated head, and the foretibial foliaceous expansions. In this work we provide a taxonomic revision of Heteroscelis. The genus and its four known species are redescribed, and one new species from Colombia, Heteroscelis vandembergi Sampaio & Campos, sp.nov., is proposed. A distribution map, and a key to the species of Heteroscelis are presented.

Morphology of interommatidial sensilla of Discocephalini (Heteroptera: Pentatomidae: Discocephalinae)

Interommatidial sensilla have been explored for their taxonomic value and other aspects in Diptera and Lepidoptera. In Heteroptera, Eurystethus is the only genus where these structures were examined in delimiting subgenera and species. This study investigates the presence, distribution, and morphology of interommatidial sensilla in Discocephalinae species and discusses the sensilla's value for cladistic and taxonomic appraisals. Twenty species of 18 genera were analyzed: 16 Discocephalini genera, one genus in Ochlerini, and one genus in Edessinae. Species' heads were observed from photographs taken with light microscopy (LM) and scanning electron microscopy (SEM). From these images, we identified eleven types of sensilla, classified into chaetica, trichoidea and coeloconica. In LM, only sensilla chaetica with a length of 40-100 μm were visible, present in six species. Under the SEM at least one type of sensillum was visible in 19 of the 20 species analyzed. No difference between the various kinds of sensilla were apparent between males and females or adults and nymphs of a given species. Both subgenera of Eurysthetus have the same type of sensillum (chaeticum type I), which suggests this is not a delimiting feature. We conclude that sensilla chaetica can be a valuable character to delimit groups of genera within Discocephalini.

Bizarre morphology in extinct Eocene bugs (Heteroptera: Pentatomidae)

Newly discovered fossil bugs (Insecta: Hemiptera: Heteroptera: Pentatomidae) from the Eocene of Messel (Germany) and Green River (North America) exhibit an exaggerated morphology including prominent spiny humeral and anterolateral angles of the pronotum and a spiny lateral abdominal margin. Especially the humeral angles are unique; they consist of expansive, rounded projections with strong spines, which is a rare trait among pentatomids. A hypothesis for the function of this extreme morphology is defence against small vertebrate predators, such as birds or reptiles. The same protuberances also produce a disruptive effect camouflaging the specimen in its environment and provide additional protection. Therefore, the extreme morphology provides primary as well as secondary anti-predator defence. The morphology of Eospinosus peterkulkai gen. et sp. nov. and E. greenriverensis sp. nov. resembles that of Triplatygini, which today occur exclusively in Madagascar, as well as that of Discocephalinae or Cyrtocorinae, which today occur in the Neotropics. Due to a lack of conclusive characters, it cannot be excluded that the fossil species may represent a case of remarkable convergence and are not related to either taxon. Phylogenetic analyses using parsimony as well as Bayesian algorithms confirmed that the new genus is a member of Pentatomidae, but could not solve its phylogenetic relationships within Pentatomidae.

Three new species of emEurystethus/em from Brazil (Hemiptera: Heteroptera: Pentatomidae)

The Heteroptera (true bugs) and its fourth-largest family Pentatomidae (stink bugs) are worldwide distributed groups with higher diversity in the tropics. The pentatomid subfamily Discocephalinae is almost restricted to the Neotropical Region, and it is divided into the tribes Discocephalini and Ochlerini. Eurystethus Mayr, 1864 is placed within Discocephalini and comprises 18 species, 16 out of them classified into two subgenera. Here we describe Eurystethus jo sp. nov., Eurystethus multipunctatus sp. nov., and Eurystethus rufodorsatus sp. nov., all occurring in Brazil, compare them to other species and provide a distribution map.

The scent of life: Foreword from the Editors

This special issue of Zootaxa is published in honor of Dr. Jocélia Grazia (Fig. 1) from the Universidade Federal do Rio Grande do Sul, Brazil, one of the world's most respected and influential active taxonomists in Heteroptera. Though she retired from her long-time position as a Full Professor, away from undergraduate classes and administrative duties, Jocélia is still an active researcher and passionate about studying true bugs. An intense conviction she passes to her many students and becomes evident in her publications. If there is one word to define Jocélia Grazia, it is energy. Even the most novice and inexperienced student perceives the enthusiasm and dedication Jocélia faces from the small bureaucratic problems through the most challenging scientific questions.

Revision of emMacropygium/em Spinola, 1837 (Hemiptera: Pentatomidae: Ochlerini) with the revalidation of three species and the description of one new species

The Ochlerini (Discocephalinae) are endemic in the Neotropical region, and the tribe currently contains 38 genera and 149 species. The monotypic Macropygium Spinola, 1837 is the most widespread ochlerine genus in the Americas, ranging from Mexico to Argentina. Macropygium reticulare (Fabricius, 1803) is one of the few Ochlerini of phytosanitary importance, transmitting Phytomonas spp. in palm crops in South America. Nonetheless its wide distribution, and phytosanitary importance, the taxonomy of Macropygium has been neglected. Here we present a revision of Macropygium, revalidate three species, Macropygium spinolae Stål, 1860, REVISED STATUS (removed from the synonymy with M. reticulare), Macropygium bifidum (Westwood, 1837), NEW COMBINATION (removed from the synonymy with M. reticulare), and Macropygium subsulcatum (Amyot Serville, 1843), REVISED STATUS (removed from the synonymy with M. reticulare). We remove Ochlerus guttipes Walker, 1867 from the synonymy with M. reticulare, and propose O. guttipes a new junior synonym of M. spinolae. Finally, we describe one new species, Macropygium graziae Silva Campos, Sp. Nov.. A key for the species of Macropygium is provided.

External morphology of the abdominal glands in Asopinae (Hemiptera: Heteroptera: Pentatomidae)

Heteropterans communicate chemically through thoracic or abdominal glandular complexes. The dorso-abdominal scent glands (DAGs) are externalized by cuticular specialized structures forming the external scent efferent system (SES). Different groups in Heteroptera present other glands, such as the Asopinae (Pentatomidae), whose males can have ventral abdominal pheromonal glands externalized by cuticular modifications, called glandular patches (GPs). Here we describe the SES of DAGs and, for the first time, the GPs of 22 Asopinae genera. The ostioles of SES 1 vary in shape. SES 2 and SES 3 were restricted to scars, indicating that only the SES 1 remains functional in adults. The GPs are found mostly in segments V and VI. We have not found any difference in the morphological pattern between the SES of species bearing GPs and those lacking it, meaning that the acquisition of GPs is likely related to some sexual behavior, thus not as a complex structure replacing any role of the DAGs. The cuticle of the GPs is microsculptured, bearing many pores surrounding the base of sensilla being the pathway for the secretions to reach the outside of the exoskeleton. The sensilla may be adaptations to increase the contact surface, assisting rapid evaporation of the volatile secretions from the pores.

Phylogenetic analysis and revision of the strangest lace bug subfamily Vianaidinae (Heteroptera: Tingidae)

In this study, we present a taxonomic review of a rarely collected subfamily of lace bugs (Vianaidinae: Tingidae: Heteroptera), including the description of nine new species and one new genus, and a phylogenetic analysis targeting its internal relationships. Anommatocoris araguanus sp. nov., A. knudsoni sp. nov., A. schuhi sp. nov., A. serratus sp. nov., A. sucreanus sp. nov., Thaumamannia insolita sp. nov. and T. urucuana sp. nov. are proposed, in addition to the new genus Henryvianaida gen. nov. with its two macropterous species, H. colombiensis sp. nov. and H. machupicchuensis sp. nov. The monophyly of all vianaidine genera is recovered and their synapomorphies are highlighted. Comments on fossil forms and insights on the future of Vianaidinae taxonomy and systematics are also included.

Morphology of Immature Stages, Chromatic Polymorphism of Adults and Natural History of Oplomus catena (Heteroptera: Pentatomidae: Asopinae)

The predatory stink bugs are well known by their behavior, but the knowledge of the immature morphology and their natural history are scarce. Studies on predatory stink bugs are important to better understand their evolution and their use as biological controllers. Here, we describe the morphology of egg and the five nymphal instars of Oplomus catena (Drury, 1782), using optical and scanning electron microscopy. In general, O. catena immatures are very distinctive from other Asopinae species already studied. The egg is black, with short aero-micropylar processes and similar to those described for Stiretrus species. The nymphs can be diagnosed by the abdominal plates very large and bright blue. The color polymorphism of adults is fully illustrated, and four color patterns are proposed. The natural history of the species is described based on field and laboratory observations. The known prey of the species is reviewed and new preys are reported. The morphological and biological traits here described are discussed in order to better understand the biological role of predatory stink bugs.

Genital coupling, morphology and evolution of male holding structures in Cicadinae (Hemiptera: Cicadidae)

Male and female genitalia include some of the most complex and morphologically diverse structures in Metazoa. Ornamentations in genitalia have been studied in several groups, and a variety of functional roles have been proposed. Although complex features of the genitalia have been observed in internal genitalia in cicadas, their functions have not yet been elucidated. These ornamentations, together with precopulatory sexual selection, make cicadas good models for evolutionary studies on genital coupling. We explore the structural interaction of male and female genitalia in Guyalna bonaerensis (Berg) (Cicadinae) and the morphology of male ornamentations in Cicadinae generally. We group these ornamentations into two traits according to their inferred function: anchoring or gripping. We analyse the theca and vesica of 24 species and perform ancestral trait reconstruction under maximum likelihood and stochastic mapping on a Bayesian tree. Ornamentations of the male vesica and the female seminal ampoule possibly ensure male attachment by working as an active lock to avoid the premature termination of intercourse. These ornamentations emerged independently in different lineages in Cicadinae, reinforcing the suggestion that they are important adaptations to achieve complete copulation. Our results foster questions for the field of sexual selection and associated mechanisms shaping the evolution of male and female genitalia.

Revision of Lineostethus (Heteroptera: Pentatomidae: Discocephalini)

LineostethusRuckes, 1966 has four species,L.clypeatus(Stål, 1862),L.graziaeHildebrand & Becker, 1982,L.marginellus(Stål, 1872), andL.tenebricornis(Ruckes, 1957); mostly restricted to Central America, but with distribution records in the southern North America.Lineostethusis one of the discocephaline genera with discoid head. The last review of the genus, from the 1980’s, focused on the genital morphology and failed to provide updated descriptions or a key to species. We had access to material from different collections, including several specimens representing new species ofLineostethus, and males ofL.marginelluswhich shows important variations in genital morphology. Here we update the generic description ofLineostethusand its known species and describe the new speciesLineostethusacuminatussp. nov. (holotype male in DZUP: Costa Rica, Guanacaste),Lineostethusauritussp. nov. (holotype male in AMNH: Mexico, Oaxaca),Lineostethusotarussp. nov. (holotype male in AMNH: Mexico, Michoacán) andLineostethussinuosussp. nov. (holotype male in DZUP: Mexico, Yucatán). Additionally, we provide identification keys and distribution maps.

Description of three new species of Glyphepomis Berg (Heteroptera: Pentatomidae: Pentatominae)

Three new species of the Glyphepomis are described: Glyphepomis dubia Campos & Souza, sp. nov., Glyphepomis amazonica Gonçalves & Campos, sp. nov. and Glyphepomis magnocephala Bianchi & Campos, sp. nov. Comparative illustrations of external and internal genitalia, distribution map of the described species, additions to the genus description, and a key to the species are provided.

Candeocoris bistillatus, new genus and new species of Ochlerini from Ecuador (Hemiptera: Heteroptera: Pentatomidae)

Recent examination of specimens from Ecuador revealed a series of males and females of an undescribed species clearly belonging to the Discocephalinae. The new species presents characteristics similar to genera of both Discocephalini and Ochlerini, preventing an undoubtful placement of the new species within any genus and tribe. We conducted a cladistic analysis to investigate the possible relationships of the new species within Discocephalinae. The new species was recovered as sister-group to the remaining Ochlerini, supporting the proposition of a new genus, so Candeocoris bistillatus Roell & Campos, gen. n. et sp. n. are described within Ochlerini. The new genus is recognized for its dark glossy aspect, tumid vertex of head, long and sinuous labrum, base of labium placed close to anterior limit of eyes, thick bristles on meso- and metatibiae, pygophore globose, and laterotergites 9 touching each other. The new species is recognized by a large yellow spot on each corium, yellow spots on each segment of the connexivum, bucculae with anterior tooth, laminar projections on superior layer of ventral rim of pygophore, vesica with a single median projection, and broad gonocoxites 8.

Factors affecting ambulance utilization for asthma attack treatment: understanding where to target interventions

OBJECTIVES

Asthma is a serious, sometimes fatal condition, in which attacks vary in severity, potentially requiring emergency medical services (EMS) ambulance treatment. A portion of asthma attacks requiring EMS ambulance treatment may be prevented with improved education and access to care. The aim of this study was to identify areas of the city with high rates of utilization of EMS ambulance for treatment, and the demographics, socio-economic status, and time of day associated with these rates, to better target future interventions to prevent emergencies and reduce cost.

STUDY DESIGN

A cross-sectional study was conducted on individuals in Houston, TX (USA) requiring ambulance treatment for asthma attacks from 2004 to 2011.

METHODS

12,155 EMS ambulance-treated asthma attack cases were linked to census tracts. High rate treatment areas were identified with geospatial mapping. Census tract demographic characteristics of these high rate areas were compared with the remainder of the city using logistic regression. The association between case level demographics and the time of day of asthma attack within the high rate area was also assessed with logistic regression.

RESULTS

EMS ambulance-treated high rate areas were identified and found to have a utilization incidence rate over six times higher per 100,000 people than the remainder of the city. There is an increased risk of location in this high rate area with a census tract level increase of percent of population: earning less than $10,000 yearly income (RR 1.21, 1.16-1.26), which is black (RR 1.08, 1.07-1.10), which is female (RR 1.34, 1.20-1.49) and have obtained less than a high school degree (RR 1.02, 1.01-1.03). Within the high rate area, case level data indicates an increased risk of requiring an ambulance after normal doctor office hours for men compared with women (RR 1.13, 1.03-1.22), for black compared with Hispanic ethnicity (RR 1.31, 1.08-1.59), or for adults (less than 41 and greater than 60) compared with children.

CONCLUSIONS

Interventions to prevent asthma emergencies should be targeted in the high rate area and towards groups identified most at risk. Consideration should be given to improved access to care after normal doctor office hours in these locations. While ambulance treatment reflects the most urgent care needs, these interventions are also expected to reduce the need for emergency room visits.

Comparing vegetation types and anthropic disturbance levels in the Atlantic forest: how do Pentatomoidea (Hemiptera: Heteroptera) assemblages respond?

The Atlantic Forest (AF) is considered the most fragmented and endangered Brazilian biome. The diversity of phytophagous insects increases after disturbances in forests, and it was hypothesized the Pentatomidae can furnish ecologically reliable information in terms of diversity in response to the changes occurring in AF. Our aim was to quantify the response of assemblages of Pentatomoidea to gradient of human disturbance in two vegetation types of the AF-dense ombrophilous forest (DOF) and mixed ombrophilous forest (MOF). Twelve transects were grouped into environmental classes, namely open, intermediate, and closed. Overall, 1,017 pentatomoids were sampled, representing 64 species. The open environment was more abundant than closed environment, though it is expected that Pentatomoidea respond with increasing abundance when under light or moderate disturbance. The MOF was more abundant than DOF, and the composition differed between both of them. Given the differences in composition between MOF and DOF, abiotic variables are important factors acting as environmental filters for Pentatomoidea, not just directly on the insects, but probably also on the nutritional support of their host plants.

Taxonomic notes on Ochlerus: revisiting Herrich-Schäffer's species (Hemiptera: Pentatomidae: Discocephalinae: Ochlerini)

The status of the three species of Ochlerus Spinola, 1837, described by Herrich-Schäffer in 1844 is reviewed. Ochlerus coriaceus and O. lutosus are removed from the synonymy of O. cinctus Spinola, 1837, while O. sordidus is transferred to Paralincus sordidus. Lectotypes are designated, and photos for each type and new records for O. coriaceus are provided.

External egg structure of the Pentatomidae (Hemiptera: Heteroptera) and the search for characters with phylogenetic importance

The chorionic structure of sixteen pentatomid species is described. Morphological patterns in different taxonomic levels are discussed. In addition, egg characters useful in cladistic analyses are listed, and some of those characters are tested for congruence with two cladistic analyses previously conducted within Pentatomidae. Descriptive studies were conducted with Banasa induta, Capivaccius bufo, Catulona pensa, Chinavia armigera, Chinavia aseada, Chinavia brasicola, Chinavia runaspis, Dichelops furcatus, Euschistus heros, Euschistus riograndensis, Euschistus paranticus, Mormidea cornicollis, Podisus distinctus, Podisus nigrispinus, Serdia apicicornis, and Thoreyella maracaja. The eggs were examined and photographed under light and scanning electron microscopy. Based on literature data, a list of 40 egg characters with potential phylogenetic importance has been compiled. Some of these characters were included in the cladistic analyses of the genus Nezara (six characters) and of the Chinavia obstinata group (five characters). Both analyses were performed in TNT with equal weighting of characters. The eggs of most of the Neotropical species studied were barrel-shaped, chorion translucent and spinose, with aero-micropylar processes that were short and clubbed. The patterns of egg morphology could be identified in Carpocorini, Procleticini, and in the genera Banasa, Chinavia, Euschistus, Mormidea, and Podisus. In the cladistic analyses, the inclusion of egg characters did not affect the topology of the trees shown in the original papers. For the analyses, the egg characters were somewhat informative. At present, a total of 286 Pentatomidae species have their egg stage described. 

Morphology of immatures of Caonabo pseudoscylax (Bergroth) (Hemiptera: Pentatomidae)

Characters of immatures are potentially useful in identifying taxa, but few immatures of Pentatomidae were described. The objectives here are to describe the egg and five nymphal instars of Caonabo pseudoscylax (Bergroth) under light and scanning electron microscopy. Adults, eggs, and nymphs were collected on Homolepsis glutinosa during 2008, in Criciúma (Santa Catarina, Brazil). The egg of C. pseudoscylax is subcylindrical, chorion reddish brown, slightly translucent, and with granulate surface. Aero-micropylar processes translucent, spongy, and strongly clavate. Nymphs without punctures, spiracles placed near the lateral abdominal margin. The dorsal abdominal gland has rounded ostioles bearing cuticular valve; spout peritreme smooth, directed anteriorly; evaporatorium network-shaped; and microsculpture poorly ornamented. Humeral angles of the pronotum were produced from fourth instar. The almost marginal placement of abdominal spiracles may diagnose the nymphs of C. pseudoscylax from first instar to adulthood.

On the genus Chinavia orian: additions to the descriptions of three species (Hemiptera: Pentatomidae)

Chinavia Orian has 79 nominal species, 32 of them occur in Brazil, and intraspecific chromatic or morphological variations are known for both immatures and adults of some species. Additions to the descriptions of Chinavia difficilis (Stål), Chinavia geniculata (Dallas), and Chinavia obstinata (Stål) are provided in here, and corrections are proposed for the pictorial key by Schwertner & Grazia for the Brazilian species of Chinavia. New distribution records are also given for the first two species.

Dalcetrapib: no off-target toxicity on blood pressure or on genes related to the renin-angiotensin-aldosterone system in rats

BACKGROUND AND PURPOSE

The association between torcetrapib and its off-target effects on blood pressure suggested a possible class-specific effect. The effects of dalcetrapib (RO4607381/JTT-705) and torcetrapib on haemodynamics and the renin-angiotensin-aldosterone system (RAAS) were therefore assessed in a rat model.

EXPERIMENTAL APPROACH

Arterial pressure (AP) and heart rate were measured by telemetry in normotensive and spontaneously hypertensive rats (SHR) receiving torcetrapib 10, 40 or 80 mg kg(-1) day(-1); dalcetrapib 100, 300 or 500 mg(-1) kg day(-1); or vehicle (placebo) for 5 days. Expression of RAAS genes in adrenal gland, kidney, aorta and lung from normotensive rats following 5 days' treatment with torcetrapib 40 mg kg(-1) day(-1), dalcetrapib 500 mg kg(-1) day(-1) or vehicle was measured by quantitative polymerase chain reaction.

KEY RESULTS

Torcetrapib transiently increased mean AP in normotensive rats (+3.7 +/- 0.1 mmHg), whereas treatment in SHR resulted in a dose-dependent and sustained increase [+6.5 +/- 0.6 mmHg with 40 mg kg(-1) day(-1) at day 1 (P < 0.05 versus placebo)], which lasted over the treatment period. No changes in AP or heart rate were observed with dalcetrapib. Torcetrapib, but not dalcetrapib, increased RAAS-related mRNAs in adrenal glands and aortas.

CONCLUSIONS AND IMPLICATIONS

In contrast to torcetrapib, dalcetrapib did not increase blood pressure or RAAS-related gene expression in rats, suggesting that the off-target effects of torcetrapib are not a common feature of all compounds acting on cholesteryl ester transfer protein.

Alpha-helix stabilization by alanine relative to glycine: roles of polar and apolar solvent exposures and of backbone entropy

The energetics of alpha-helix formation are fairly well understood and the helix content of a given amino acid sequence can be calculated with reasonable accuracy from helix-coil transition theories that assign to the different residues specific effects on helix stability. In internal helical positions, alanine is regarded as the most stabilizing residue, whereas glycine, after proline, is the more destabilizing. The difference in stabilization afforded by alanine and glycine has been explained by invoking various physical reasons, including the hydrophobic effect and the entropy of folding. Herein, the contribution of these two effects and that of hydrophilic area burial is evaluated by analyzing Ala and Gly mutants implemented in three helices of apoflavodoxin. These data, combined with available data for similar mutations in other proteins (22 Ala/Gly mutations in alpha-helices have been considered), allow estimation of the difference in backbone entropy between alanine and glycine and evaluation of its contribution and that of apolar and polar area burial to the helical stabilization typically associated to Gly-->Ala substitutions. Alanine consistently stabilizes the helical conformation relative to glycine because it buries more apolar area upon folding and because its backbone entropy is lower. However, the relative contribution of polar area burial (which is shown to be destabilizing) and of backbone entropy critically depends on the approximation used to model the structure of the denatured state. In this respect, the excised-peptide model of the unfolded state, proposed by Creamer and coworkers (1995), predicts a major contribution of polar area burial, which is in good agreement with recent quantitations of the relative enthalpic contribution of Ala and Gly residues to alpha-helix formation.

Native-specific stabilization of flavodoxin by the FMN cofactor: structural and thermodynamical explanation

Flavodoxins are useful models to investigate protein/cofactor interactions. The binding energy of the apoflavodoxin-FMN complex is high and therefore the holoflavodoxin is expected to be more stable than the apoprotein. This expectation has been challenged by reports on the stability of Desulfovibrio desulfuricans flavodoxin indicating that FMN binds to the unfolded polypeptide with similar affinity as to the native state, thus causing no net effect on protein stability. In previous work, we have analyzed in detail the stability of the apoflavodoxin from Anabaena PCC 7119 and the energetics of its functional complex with FMN. Here, we use the Anabaena holoprotein to directly investigate the contribution of the bound cofactor to protein stability through a detailed analysis of the chemical and thermal denaturation equilibria. Our data clearly shows that FMN binding largely stabilizes the protein towards both chemical and thermal denaturation, and that the stabilization observed at 25 degrees C in low ionic strength conditions is precisely the one expected if full release of the cofactor takes place upon flavodoxin unfolding. On the other hand, the binding of FMN to the native polypeptide is shown to simplify the thermal unfolding so that, while apoflavodoxin follows a three-state mechanism, the holoprotein unfolds in a two-state fashion. Comparison of the X-ray structure of native apoflavodoxin with the phi-structure of the thermal intermediate indicates that the increase in cooperativity driven by the cofactor originates in its preferential binding to the native state, which is a consequence of the disorganization in the intermediate of the FMN binding loops and of an adjacent longer loop.

Equilibrium Φ-Analysis of a Molten Globule: The 1-149 Apoflavodoxin Fragment

The apoflavodoxin fragment comprising residues 1-149 that can be obtained by chemical cleavage of the C-terminal alpha-helix of the full-length protein is known to populate a molten globule conformation that displays a cooperative behaviour and experiences two-state urea and thermal denaturation. Here, we have used a recombinant form of this fragment to investigate molten globule energetics and to derive structural information by equilibrium Phi-analysis. We have characterized 15 mutant fragments designed to probe the persistence of native interactions in the molten globule and compared their conformational stability to that of the equivalent full-length apoflavodoxin mutants. According to our data, most of the mutations analysed modify the stability of the molten globule fragment following the trend observed when the same mutations are implemented in the full-length protein. However, the changes in stability observed in the molten globule are much smaller and the Phi-values calculated are (with a single exception) below 0.4. This is consistent with an overall and significant debilitation of the native structure. Nevertheless, the fact that the molten globule fragment can be stabilised using as a guide the native structure of the full-length protein (by increasing helix propensity, optimising charge interactions and filling small cavities) suggests that the overall structure of the molten globule is still quite close to native, in spite of the lowered stability observed.

Genetic targeting of the brain renin-angiotensin system in transgenic rats: Impact on stress-induced renin release

The advance of genetic technologies to permit tissue-specific targeted gene manipulation allowed the development of transgenic models with alterations of the renin-angiotensin (RAS) solely in the brain. We have used such methodology to develop a transgenic rat with a brain specific alteration of the RAS [TGR(ASrAOGEN)], in order to elucidate a causative role for the brain RAS and its relevance in different pathophysiological processes. The TGR(ASrAOGEN) rats have decreased levels of angiotensinogen (AOGEN) throughout the brain because of an antisense inhibition of the astroglial AOGEN synthesis. In this review we aimed at summarizing the experience obtained from utilizing the TGR(ASrAOGEN) rat model to study the brain RAS and present novel results providing evidence for the involvement of this system in stress-induced renin release.

Sequential FISH analysis with rDNA genes and Ag-NOR banding in the lady beetle Olla v-nigrum (Coleoptera: Coccinellidae)

We have characterized the meiosis of Olla v-nigrum by standard analysis, performed a NOR study using NOR banding, FISH of rDNA genes and sequential FISH/AgNOR analysis, and adapted the FISH methodology to Coccinellidae. The chromosome number determined at metaphase I was n = 9 + Xyp. At zygotene it was possible to identify the sex vesicle which presented a deeply stained heteropycnotic block. Chromosome X is much larger than the y and the two combine, forming a "parachute" in metaphase I. FISH analysis using a probe of rDNA genes 18S, 28S and 5.8S of D. melanogaster was used to map the genes in the sex vesicle. The NOR band showed high gene activity in this region. These results were confirmed using sequential FISH/Ag NOR analysis. The data obtained for Olla v-nigrum agree with the classical hypothesis raised to explain the type of sex chromosome association in a parachute format (Xyp) as being due to the presence of nucleolar material. The chromosome number and parachute configuration during metaphase I in this species agree with the basic karyotype of most Coleopterans. The major adaptation of the FISH method was the simultaneous denaturation and hybridization that permitted preservation of chromosome morphology, an essential factor when the chromosomes are small.

Inheritance pattern of RAPD markers in Melipona quadrifasciata (Hymenoptera: Apidae, Meliponinae)

Melipona quadrifasciata is an important pollinator agent in several regions of Brazil. Data concerning the genetics of this species are scarce in the literature. In this work we used the random amplified polymorphic DNA (RAPD) technique to determine the degree of polymorphism and the inheritance pattern of these molecular markers in this species. Our ultimate goal is to establish tools to be used in the study of the genomic organization of M. quadrifasciata. Genomic DNA from progenies F(1) and BC(1) were assayed with 79 different primers, yielding an average of 6.67 bands and 1.68 polymorphisms per primer. Three types of polymorphisms were detected: band presence/absence, band intensity, and fragment-length polymorphisms. Most of the observed polymorphisms were band presence/absence, typical of RAPD-dominant markers. The number of observed polymorphisms and their segregation in accordance with a Mendelian proportion confirm the importance of this technique for genome analysis of species like M. quadrifasciata that are poorly studied at the genetic level.

A comparative study of the thermal stability of plastocyanin, cytochrome c(6) and Photosystem I in thermophilic and mesophilic cyanobacteria

Cytochrome c(6) (Cyt) from the thermophilic cyanobacterium Phormidium laminosum has been purified and characterized. It is a mildly acidic protein, with physicochemical properties very similar to those of plastocyanin (Pc). This is in agreement with the functional interchangeability of the two metalloproteins as electron donors to Photosystem I (PS I). The kinetic analyses of the interaction of Pc and Cyt with Photosystem I show that both metalloproteins reduce PS I with similar efficiencies, according to an oriented collisional kinetic model involving repulsive electrostatic interactions. The thermostability study of the Phormidium Pc/PS I system compared with those from mesophilic cyanobacteria (Synechocystis, Anabaena and Pseudanabaena) reveals that Pc is the partner limiting the thermostability of the Phormidium couple. The cross-reactions between Pc and PS I from different organisms demonstrate not only that Phormidium Pc enhances the stability of the Pc/PS I system using PS I from mesophilic cyanobacteria, but also that Phormidium PS I possesses a higher thermostability than the other photosystems.

The karyotype of the parasitoid Chelonus insularis Cresson (Hymenoptera, Braconidae, Cheloninae)

The karyotype of Chelonus insularis (Hymenoptera, Braconidae, Cheloninae) is described. The males show an haploid number of seven chromosomes and the females a diploid number of fourteen chromosomes, confirming haplo-diploid sex determination. Comparisons of these results with karyotypes of other species of the same family were done and a possible mechanism involved in the karyotype evolution of this species is discussed.

The B chromosome system of Trypoxylon (Trypargilum) albitarse (Hymenoptera, Sphecidae) 1. Banding analysis

Karyotypic analyses of 366 specimens of the solitary wasp Trypoxylon (Trypargilum) albitarse collected from ten populations in the municipalities of Viçosa and Porto Firme (Minas Gerais, Southeastern Brazil), revealed the presence of two morphological types of supernumerary (B) chromosomes. C-banding and fluorochrome banding suggest that the B chromosomes of T. albitarse may have originated from heterochromatin breaks within the standard (A) chromosome complement.