Alkanes of four related moth species,Helicoverpa and Heliothis

Comparison of the presence and quantities of cuticular hydrocarbons has been used successfully for identifying sibling species and races of several groups of insects. This approach has been extended to four species of moths previously regarded as belonging to the same genus, Heliothis. Gas chromatography was used to quantify the numerous high-molecular weight alkanes found on the cuticle of two pairs of closely related species: Helicoverpa zea and Helicoverpa armigera, and Heliothis virescens and Heliothis subflexa. Both sexes of H. zea and H. armigera contained different quantities of several alkanes that could be used for unambiguous identification. Similar comparisons of H. subflexa and H. virescens showed four peak ratios that were different for each species. Sexual dimorphism was minor in H. subflexa and H. virescens.     

Presence of corazonin in three insect species, and isolation and identification of [His7]corazonin from Schistocerca americana.

An ELISA for corazonin, a cardioactive neuropeptide from the American cockroach, Periplaneta americana, was developed. It was used to isolate corazonin from the cockroach Nauphoeta cinerea, the locust Schistocerca americana, and the hawkmoth Manduca sexta. The peptides from Nauphoeta and Manduca had the same retention times as Periplaneta corazonin, and their amino acid compositions also suggested that these peptides are identical with corazonin. The corazonin-immunoreactive peptide from Schistocerca eluted slightly earlier on HPLC than corazonin, and its structure was determined to be [His⁷]corazonin, or pGlu-Thr-Phe-Gln-Tyr-Ser-His-Gly-Trp-Thr-Asn-amide. These results indicate that corazonin is generally present in insects and that its structure has been well conserved.     

Tests of potential adipokinetic hormone precursor related peptide (APRP) functions: lack of responses.

The adipokinetic hormone (AKH) precursor related peptides (APRPs) are end products of the synthesis of the well-conserved AKHs. The large amount of metabolic energy devoted to APRP synthesis suggests they have an important function(s) in the insects. Several functions have been proposed, but currently none are known. We tested whether the APRPs stimulate hyperlipemia, hypertrehalosemia, fat body glycogen phosphorylase activation, Malpighian tubule secretion, and hindgut myotropia. Surprisingly, none of these responses were stimulated by APRPs isolated from the lubber grasshopper, Romalea microptera (= guttata). In addition, the APRPs delivered in concert with AKHs did not significantly increase hyperlipemia, hypertrehalosemia, or phosphorylase activation over the AKHs alone. Our data discount several proposed functions for the APRPs. Arch.     

The adipokinetic hormone family in Chrysomeloidea: structural and functional considerations

The presented work is a hybrid of an overview and an original research paper on peptides belonging to the adipokinetic hormone (AKH) family that are present in the corpora cardiaca of Chrysomeloidea. First, we introduce the AKH/red pigment-concentrating hormone (RPCH) peptide family. Second, we collate the available primary sequence data on AKH peptides in Cerambycidae and Chrysomelidae, and we present new sequencing data (from previously unstudied species) obtained by liquid-chromatography coupled with ion trap electrospray ionisation mass spectrometry. Our expanded data set encompasses the primary structure of AKHs from seven species of Cerambycidae and three species of Chrysomelidae. All of these species synthesise the octapeptide code-named Peram-CAH-I (pGlu-Val-Asn-Phe-Ser-Pro-Asn-Trp amide). Whereas this is the sole AKH peptide in Cerambycidae, Chrysomelidae demonstrate a probable event of AKH gene duplication, thereby giving rise to an additional AKH. This second AKH peptide may be either Emppe-AKH (pGlu-Val-Asn-Phe-Thr-Pro-Asn-Trp amide) or Peram-CAH-II (pGlu-Leu-Thr-Phe-Thr-Pro-Asn-Trp amide). The peptide distribution and structural data suggest that both families are closely related and that Peram-CAH-I is the ancestral peptide. We hypothesise on the molecular evolution of Emppe-AKH and Peram-CAH-II from the ancestral peptide due to nonsynonymous missense single nucleotide polymorphism in the nucleotide coding sequence of prepro-AKH. Finally, we review the biological significance of the AKH peptides as hyperprolinaemic hormones in Chrysomeloidea, i.e. they cause an increase in the circulating concentration of proline. The mobilisation of proline has been demonstrated during flight in both cerambycid and chrysomelid beetles.     

Comparative water relations of four Mediterranean oak species

The water relations and responses of two evergreen (Quercus ilex L. and Q. suber L.) and two deciduous (S. afares Pomel. and Q. faginea Will.) Quercus species were studied under experimental conditions. Two-year old seedlings grown in 30 l. pots were subjected to a drying period during which stomatal conductance, pre-dawn potential and minimum foliar potential were measured.The results shows that, for all species, the daily course of stomatal conductance agrees with the patterns proposed by Hinckley et al. (1978 & 1983). Concurrent with the species responses to short-term variation in water availability, it was found that pre-dawn leaf water potential controlled the maximum daily leaf conductance. There was a strong correlation between pre-dawn leaf potential and maximum daily conductance as described by the reciprocal function g_{srmax for}=(-0.47+2.61._p)^-1 the evergreen oaks and g_{srmax for}=(-1.94+7.39._p)^-1 for the deciduous species. These differences between the two groups may partialy explain their geograhic distributions, and suggest general questions concerning the mechanisms which optimize water-use efficiency in Mediterranean oak species.     

Comparative phytochemical analysis of four Mexican Nymphaea species

Four Mexican Nymphaea species, N. ampla, N. pulchella, N. gracilis and N. elegans belonging to subgenera Brachyceras were analyzed. In this work two 5-glycosyl isoflavones, 7,3',4'-trihydroxy-5-O-beta-D-(2'-acetyl)-xylopyranosylisoflavone (1) and 7,3',4'-trihydroxy-5-O-alpha-L-rhamnopyranosylisoflavone (2), were isolated from N. ampla and N. pulchella, respectively, together with other known 3-glycosyl flavones and triterpene saponins from the same four species. The structures were elucidated by 1D and 2D NMR, FABMS, and other spectroscopic analyses. These results confirmed that the four species were different from each other and established that N. pulchella represents a different taxa than N. ampla. In addition, the 5-glycosyl isoflavones could be considered as a taxonomic character of this group of plants.     

Comparative cytogenetics in four species of Palinuridae: B chromosomes, ribosomal genes and telomeric sequences

The evolutionary pathway of Palinuridae (Crustacea, Decapoda) is still controversial, uncertain and unexplored, expecially from a karyological point of view. Here we describe the South African spiny lobster Jasus lalandii karyotype: n and 2n values, heterochromatin distribution, nucleolar organizer region (NOR) location and telomeric repeat structure and location. To compare the genomic and chromosomal organization in Palinuridae we located NORs in Panulirus regius, Palinurus gilchristi and Palinurus mauritanicus: all species showed multiple NORs. In J. lalandii NORs were located on three chromosome pairs, with interindividual polymorphism. In P. regius and in the two Palinurus species NORs were located on two chromosome pairs. In the two last species 45S ribosomal gene loci were also found on B chromosomes. In addition, the nature and location of telomeric repeats were investigated by FISH in J. lalandii, P. gilchristi, P. mauritanicus Palinurus elephas, and P. regius (Palinuridae, Achelata), and in Scyllarus arctus (Scyllaridae, Achelata): all these Achelata species showed the (TTAGG)n pentameric repeats. Furthermore, in J. lalandii these repeats occurred in all the telomeres and in some interstitial chromosomal sites, associated with NORs.     

A quantitative study of adipokinetic hormone of the firebug,Pyrrhocoris apterus

The development of an enzyme-linked immunoassay (ELISA) for the adipokinetic neuropeptide hormone, Pya-AKH, from the firebug Pyrrhocoris apterus L. is described. The ELISA measures as little as 20 fmol of Pya-AKH. Tested against a range of synthetic peptides, the assay has a high sensitivity for peptides containing the C-terminal motif FTPNWamide. The amounts of Pya-AKH in the brain, corpora cardiaca, suboesophageal ganglia, and fused thoracic and abdominal ganglionic mass are very small, with only the corpora cardiaca containing appreciable levels of the hormone (ca. 4 pmol per bug). Preliminary estimates of the persistence of the hormone in the haemolymph are consistent with values determined for AKHs in other insects, and suggest that Pya-AKH has a rapid turnover with a half-life of ca. 18 min. Measurements of circulating titres of AKH in Pyrrhocoris are only possible in the ELISA described here by using pooled samples of haemolymph, and after preliminary clean-up of the haemolymph samples. The titre of Pya-AKH in resting reproductive female Pyrrhocoris is ca. 1 fmol/μl.     

Effects of adipokinetic hormone and its related peptide on maintaining hemolymph carbohydrate and lipid levels in the two-spotted cricket,Gryllus bimaculatus

Adipokinetic hormone (AKH) regulates energy homeostasis in insects by mobilizing lipid and carbohydrate from the fat body. Here, using RNA sequencing data, we identified cDNAs encoding AKH (GbAKH) and its highly homologous hormone AKH/corazonin-related peptide (GbACP) in the corpora cardiaca of the two-spotted cricket, Gryllus bimaculatus. RT-PCR revealed that GbAKH and GbACP are predominantly expressed in the corpora cardiaca and corpora allata, respectively. Phylogenetic analysis confirmed that the identified GbAKH and GbACP belong to the clades containing other AKHs and ACPs, respectively. Injection of synthetic GbAKH and GbACP elevated hemolymph carbohydrate and lipid levels and reduced food intake significantly. In contrast, knockdown of GbAKH and GbACP by RNA interference increased the food intake, although hemolymph lipid level was not altered. Collectively, this study provides evidence that ACP regulates hemolymph carbohydrate and lipid levels in cricket, possibly collaborative contribution with AKH to the maintenance of energy homeostasis.     

A possible molecular ancestor for mollusk APGWamide,insect adipokinetic hormone,and crustacean red pigment concentrating hormone

Precursor structures of various members of the neuropeptide family adipokinetic hormone/red pigment concentrating hormone (AKH/RPCH) of mandibular arthropods and the APGWamide family of mollusks were compared. Amino acid alignments showed a common overall architecture (signal peptide, active peptide, related peptide), with a similar α helix–random coil secondary structure. DNA sequence alignments revealed close similarities between the genes encoding for the peptides of the two families. The APGWamide genes are larger than the AKH/RPCH genes. The sequence environment occupied by introns is similar in AKH/RPCH and APGWamide genes. Such similarities suggest that these peptide families might have been originated by gene rearrangements from a common ancestor having either an AKH/RPCH/APGWamide-like structure or both an AKH/RPCH-like and an APGWamide-like structures. In the former model, DNA fragments could have been gained when the ancestor evolved to mollusks and it could have lost nucleotides when the progression to mandibular arthropods took place. In the second model, AKH/RPCH-like structures could have been fused during evolution toward mandibular arthropods, whereas in mollusks they could have been lost with the possible amplification of the APGWamide-like structure. Loss of domains in exon 1 may have originated the signal peptide and the first codon of the active RPCH. In exon 2, loss of domains possibly determined the junctions of codons 2 to 5 with the loss of a APGWamide copy; exon 3 underwent fewer variations. The similarity of the mollusk APGWamide precursors is closer to that of the RPCH family than the insect AKH family, indicating an earlier evolutionary departure.     

Comparative feeding ecology of four sympatric skate species off central California, USA

The big (Raja binoculata), California (R. inornata), longnose (R. rhina), and sandpaper (Bathyraja kincaidii), skates are commonly found on soft-bottom regions of the central California continental shelf and upper slope. The feeding ecology of this assemblage was compared to evaluate the degree of trophic separation among species, based on the results of previous species-specific diet studies. Specimens were collected from fishery independent trawl surveys conducted during September 2002–March 2003 at depths of 9–536 m. Using single and compound measures, diet composition of small (≤60 cm TL) and large (>60 cm TL) individuals were compared within continental shelf (≤200 m) and slope (>200 m) regions using traditional, multivariate, and novel techniques. Diet compositions within size classes were similar in both regions. Diet compositions between size classes generally differed, however, with fishes more important and crustaceans (especially shrimps and euphausiids) less important in the diets of large individuals. Crabs contributed substantially to skate diet compositions on the shelf, but were uncommon prey items at deeper depths, probably because of their relative scarcity in slope waters. Conversely, cephalopods were common prey items at slope depths, but were rarely ingested at shelf depths. The studied skate assemblage appears to consist primarily of generalist crustacean and fish predators that exhibit high dietary overlap at similar sizes. It is possible that resource competition among skates and groundfish species has been reduced because of considerable recent declines in the biomass of upper trophic level groundfishes. Skates may therefore play important roles in contemporary benthic food web dynamics off central California.     

Comparative study of mycorrhizal susceptibility and anatomy of four palm species

A morphological and anatomical study of the root systems of the palm species Brahea armata S. Watson, Chamaerops humilis L., Phoenix canariensis Chabaud and Phoenix dactylifera L. has been carried out to determine possible mycorrhizal colonization sites. Furthermore, the arbuscular mycorrhizal (AM) anatomical types formed by the four palm species in association with Glomus mosseae (Nicol. & Gerd.) Gerdemann & Trappe have been examined. The presence of a continuous sclerenchymatic ring in the outer cortex and aerenchyma in the inner cortex that are anatomical indicators of mycorrhizal nonsusceptibility in all four palm species is observed. The root systems of B. armata and C. humilis present only one group of third-order roots, while the third-order roots of P. canariensis and P. dactylifera may be divided into five different groups: short thick roots, mycorrhizal thickened roots, fine short roots, fine long roots, and pneumatorhizas. Third-order and some second-order roots of B. armata and C. humilis are susceptible to colonization by AM fungi, while only the mycorrhizal thickened roots form mycorrhizas with arbuscules in the Phoenix species. The root system of the Phoenix species also presents AM colonization in fine roots with only intraradical hyphae and spores, but without arbuscules, and pseudomantles of spores anchored in the pneumatorings of the second-order roots, which are described for the first time. The mycorrhizas formed by the four palm species are of an intermediate type, between the Arum and the Paris types, and are characterized by intercalary arbusculate coils and not only by intracellular but also by intercellular fungal growth. Our study suggests that a different degree of adaptation may exist among palm mycorrhizas toward the slow growth of palms and low spore numbers in the soil where they grow.     

Preliminary characterization of glycogen phosphorylase activating hormone and adipokinetic hormone from Manduca sexta corpora cardiaca

ABSTRACT. An attempt was made to separate glycogen phosphorylase activating hormone (GPAH) and adipokinetic hormone (AKH) from the corpora cardiaca (CC) of the moth Manduca sexta (Lepidoptera: Sphingidae) by separating extracts of CC on various chromotographic media, but it was not possible to conclude whether GPAH and AKH are activities of one or of two different peptides. Both activities elute together from glass beads, from Sephadex G-25 and from Sephadex LH-20 columns. In the separation experiments with glass beads and G-25 the activities eluted as a single peak, but using LH-20 we found two peaks exhibiting both activities. The major peak eluted at 1.25 × V_t, which is very similar to locust AKH, while the smaller second peak eluted at O.74 × V _t. Cross injections of CC extracts from M. sexta into Locusta migratoria and CC extracts from L. migratoria into M. sexta suggest that GPAH and the AKH from M. sexta are not identical with the decapeptide AKH from locusts.     

Comparative study of cultures of four species of the genusOudemansiella

Thirty stationary and submerged cultures of species of the genusOudemansiella Speg.,viz. two narrow-region species (O. brunneomarginata, O. canarii) and two primarily wideregion species (O.mucida, O. radicata) were compared. Stationary cultures have identical macroscopic and microscopic features (they produce crust, teleomorph, large thick-walled basidiospores with an apiculum and an uneven surface, dikaryotic hyphae have clamp connections). “Coils” were detected in the mycelium of two species by SEM. Submerged cultures produce antibacterial and particularly antifungal antibiotics, although with various intensity.O. brunneomarginata was first studied in pure culture and its microstructures were first studied by SEM. It could be demonstrated that this species is related with other representatives of the genusOudemansiella. In the present taxonomy of basidiomycetes it is advisable to extend and deepen data concerning a single genusOudemansiella with a series of interspecies taxons, without impairing “borders” of the genus.