Intraspecific scaling of flight power in the bat Glossophaga soricina (Phyllostomidae)

Aerodynamic theory predicts that power output during flight should vary with body mass by an exponent of 1.56 when wing morphology remains constant (within an individual), and by an exponent of 1.19 when wing morphology changes with body mass (within a species or between species). I tested these predictions by estimating the power input during horizontal flight in three pregnant and two subadult Glossophaga soricina using a multivariate regression model. This analysis yielded power input during resting and flight as well as the energetic equivalent of change in body mass. A comparison of the estimated flight power for pregnant G. soricina, with published data on flight power of non-pregnant adults, revealed that energy turnover in flight is highest for pregnant G. soricina. Flight power of a 13-g pregnant G. soricina was even higher than that of a 16-g non-pregnant Glossophaga longirostris. A least-squares regression analysis yielded the following equations for the intraspecific scaling of flight power with body mass: power input during horizontal flight (P _f )=24099 body mass (bm; kg)^2.15 (r ²=0.97) for the intra-individual allometry (pregnancy) and P _f =113 bm(kg)^0.95 (r ²=0.99) for the inter-individual allometry (ontogeny). Both mass exponents are not significantly different from the predicted values for the scaling relationship of flight power within an individual (1.56) and within a species (1.19). This is the first measurement of power input during flight for subadult and pregnant bats. Accepted: 11 May 2000     

Hox genes in the honey bee Apis mellifera

Hox genes are known to control the identity of serially repeated structures in arthropods and vertebrates. We analyzed the expression pattern of the Hox genes Deformed (Dfd), Sex combs reduced (Scr), Antennapedia (Antp), and Ultrabithorax/abdominal-A (Ubx/abd-A) from the honey bee Apis mellifera. We also cloned a cDNA with the complete coding region of the Antennapedia gene from Apis. Comparison with Antp proteins from other insect species revealed several regions of homology. The expression patterns of the isolated Hox genes from Apis showed that the original expression patterns of Dfd, Scr, and Antp appear between late blastoderm and early germ band stage in a temporal and spatial sequence. Each of them shows up as a belt, spanning approximately two segment anlagen, Dfd in the anterior gnathal region, Scr in the posterior gnathal and anterior thoracic region, and Antp in the thoracic region. Following expansion of the Antp domain in the abdomen as a gradient towards the posterior, Ubx/abd-A expression appears laterally in the abdomen. During gastrulation and in the germ band stage the domains of strong expression do not overlap any more, but touch each other. After gastrulation the borders of the expression domains partly correlate with parasegment and partly with segment boundaries. Laterally, gaps between the domain of each gene may show no expression of any of the genes examined. Received: 30 August 1999 / Accepted: 28 April 2000     

A population genetic analysis of migration: the case of the noctule bat (Nyctalus noctula)

Although rarely assessed, the population genetics of hibernating colonies can help to understand some aspects of population structure, even when samples from nursery or mating colonies are not available, or in studies of migration when both types of samples are available and can be compared. Here we illustrate both points in a survey of mitochondrial DNA (mtDNA) control region sequences used to study the population genetics of hibernating colonies of a migrating species, the noctule bat (Nyctalus noctula). Lacking samples from Scandinavian nursery colonies, we use a North European hibernacula to suggest that Scandinavian populations are isolated from Central and East European colonies. Then, we compare genetic diversities of nursery and hibernating colonies. We find a significantly higher haplotype diversity in hibernacula, confirming that they consist of individuals from different nursery colonies. Finally, we show that pairwise comparisons of the haplotype frequencies of nursery and hibernating colonies contain some information on the migration direction of the noctule bat.     

20-Hydroxyecdysone-induced differentiation and apoptosis in the Drosophila cell line, l(2)mbn

20-Hydroxyecdysone has an inhibitory effect on the proliferation of l(2)mbn cells, causes vacuolization and fragmentation of cells, and promotes a strong phagocytotic activity. From several lines of evidence, it can be concluded that 20-hydroxyecdysone induces apoptosis. Long-term video observations following the fate of individual cells, scanning and transmission electron microscopy reveal the typical characteristics of apoptosis: sequestration of small cellular protuberances or larger parts of the cell with nuclear fragments (apoptotic bodies), chromatin condensation, condensation and vesiculation of cytoplasm, whereas the mitochondria retain their normal appearance. The induction of apoptosis by 20-hydroxyecdysone was confirmed by the TUNEL reaction and quantitatively determined by a method based on this reaction. Onset of apoptosis precedes phagocytotic activity. JH III alone has no clear-cut effect on l(2)mbn cells. In double treatments, the inhibitory effect of 20-hydroxyecdysone on cell proliferation is significantly reduced by the addition of JH III. Whether or not JH III also reduces apoptotic activity is not yet clear. It is shown that the l(2)mbn cell line is an advantageous model system for the exploration of steroid-induced apoptosis.     

Evolution of Histone H4 and H3 Genes in Different Ciliate Lineages

The histones H4 are known as highly conserved proteins. However, in ciliates a high degree of variation was found compared both to other eukaryotes and between the ciliate species. To date, only H4 histones of species belonging to two distantly related classes have been investigated. In order to obtain more detailed information on histone H4 variation in ciliates we undertook a comprehensive sequence analysis of PCR-amplified internal H4 fragments from 12 species belonging to seven out of the nine currently recognized ciliate classes. In addition, we used PCR primers to amplify longer fragments of H3 and H4 genes including the intergenic region. The encoded amino acid sequences reveal a high number of differences when compared with those of other eukaryotes and the ciliate species investigated. Furthermore, in some species H4 gene variants were detected, which result in amino acid differences. The greatest number of substitutions and insertions found was in the amino terminal region of the H4 histones. However, all sequences possess a conserved region corresponding to those of all other eukaryotic H4 histones. The histone gene variations were used to reconstruct phylogenetic relationships. The tree from our data matches perfectly with the ribosomal RNA data: The heterotrichs, which were considered as a late branching lineage, diverge at the base of the ciliate tree and groups formerly thought to represent ancestral lineages now appear as highly derived ciliates. Received: 4 April 1997 / Accepted: 1 August 1997     

Electron microscopical localization of chitin in the cuticle of Halicryptus spinulosus and Priapulus caudatus (Priapulida) using gold-labelled wheat germ agglutinin: phylogenetic implications for the evolution of the cuticle within the Nemathelminthes

 The ultrastructure of the cuticle of adult and larval Priapulus caudatus and Halicryptus spinulosus is investigated and new features of cuticle formation during moulting are described. For the localization of chitin by TEM wheat germ agglutinin coupled to colloidal gold was used as a marker. Proteinaceous layers of the cuticle are revealed by digestion with pronase. The cuticle of larval and adult specimens of both species consists of three main layers: the outer, very thin, electron-dense epicuticle, the electron-dense exocuticle and the fibrillar, electron-lucent endocuticle. Depending on the body region, the exocuticle comprises two or three sublayers. The endocuticle can be subdivided into two sublayers as well. In strengthened parts such as the teeth, the endocuticle becomes sclerotized and appears electron-dense. Only all endocuticular layers show an intense labelling with wheat germ agglutinin-gold conjugates in all investigated specimens. Additional weak labelling is observed in the exocuticle III layer of the larval lorica of P. caudatus. All other cuticular layers remain unlabelled. Chitinase dissolves the unsclerotized endocuticular layers almost completely, but also exocuticle II and partly the loricate exocuticle III. The epicuticle, the homogeneous exocuticle I and the sclerotized endocuticle are not affected by chitinase. The labelling is completely prevented in all layers after incubation with chitinase. Pronase dissolves all exocuticular layers, but not evenly. The presumably sclerotized regions of exocuticle I are not affected as well as the complete epicuticle and the endocuticle. All cuticular features of the Priapulida are compared with the cuticle of each high-ranked taxon within the Nemathelminthes with special regard to the occurrence of chitin. Based on this out-group comparison it can be concluded that: (1) a two-layered cuticle with a trilaminate epicuticle and a proteinaceous basal layer represents an autapomorphic feature of the Nemathelminthes, (2) the stem species of the Cycloneuralia have already evolved an additional basal chitinous layer, (3) such a three-layered cuticle is maintained as a plesiomophy in the ground pattern of the Scalidophora and (4) in the Nematoida, the chitinous basal layer is replaced by a collagenous one at least in the adults; the synthesis of chitin is restricted to early developmental phases or the pharyngeal cuticle. Accepted: 12 March 1998     

Dorymenia troncosoi sp. nov. (Mollusca Solenogastres: Proneomeniidae), a new species from the South Shetland Islands (Antarctica)

During the Spanish oceanographic expedition BENTART '95, carried out in Antarctic waters off Livingston Island (South Shetland Islands), five small specimens of a new species of Solenogastres-Cavibelonia, Dorymenia troncosoi sp. nov., were collected at a depth of 65–240 m on a silt bottom. The species is characterized by the presence of a pallial cavity with four pouches (a dorsal, two lateral and a ventral pouch), seminal receptacles that open into the spawning ducts through a short duct, radula having 9–11 teeth per row (1 central and 4–5 lateral, all the same size), the end of the copulatory spicules having a cross-section in the shape of a four-pointed star, and abdominal spicules present. These characteristics separate this species from other species of the genus, particularly from Dorymenia profunda, which is the most similar. Received: 9 April 1998 / Accepted: 12 June 1998     

Signal transduction in isolated fat body from the cockroach Blaptica dubia exposed to hypertrehalosaemic neuropeptide

Hypertrehalosaemic hormones stimulate trehalogenesis while inhibiting glycolysis in cockroach fat body. Signal transduction of the hypertrehalosaemic peptide Bld HrTH was examined in isolated fat body of the Argentine cockroach Blaptica dubia with respect to its effects on the increase in trehalose production and decrease in the content of the glycolytic activator fructose 2,6-bisphosphate in the tissue. Cyclic AMP does not seem to be involved in these processes as the cAMP analogue cpt-cAMP and the phosphodiesterase inhibitor IBMX, which both permeate cell membranes, had no effect on either parameter. Octopamine at physiological concentrations (10⁻⁷ mol · l⁻¹) was also ineffective, but at 10⁻⁵ mol · l⁻¹ or above, octopamine stimulated trehalose production although the content of fructose 2,6-bisphosphate in fat body was not affected. Both calcium entry and the release of Ca²⁺ from intracellular stores seem to be involved in the action of the hormone. If Ca²⁺ was omitted from the incubation medium, the hormone stimulated trehalose production less, though still significantly, whereas the hormone effect on fructose 2,6-bisphosphate was completely abolished in the absence of extracellular Ca²⁺. With Ca²⁺ present in the medium, the effect of the hormone on fructose 2,6-bisphosphate could be fully mimicked by the calcium ionophore A23187, suggesting that calcium entry is a␣decisive step in this signalling pathway. Trehalose production, on the other hand, was increased by thimerosal and thapsigargin which increase cytosolic Ca²⁺ from intracellular stores, whereas thimerosal in the absence of extracellular Ca²⁺ increased rather than decreased the content of fructose 2,6-bisphosphate, thus dissociating the two effects, which are normally coordinated by the hormone. Trehalose production and the content of fructose 2,6-bisphosphate were not significantly affected by mepacrine and mellitin, which are known to inhibit, respectively stimulate, phospholipase A₂. Our data suggest that the effects of Bld HrTH on the stimulation of trehalose production and reduction of fructose 2,6-bisphosphate content in fat body are mediated by Ca²⁺, but that different signalling pathways are involved, suggesting that the two processes, although they are functionally linked, could be regulated separately. Accepted: 10 November 1997     

Morphology of skin incubation in Pipa carvalhoi (Anura: Pipidae)

South American Pipidae show a unique reproductive mode, in which the fertilized eggs develop in temporarily formed brood chambers of the dorsal skin after eggs have been deposited on the back of the female. We studied the skin incubation of Pipa carvalhoi using light microscopy and scanning electron microscopy. The skin consists of a stratified epithelium with a one‐layered stratum corneum, and the dermis. The dermis of the dorsal skin of nonreproductive and reproductive females lacks a distinct stratum compactum, which is typical for most anuran skins. The entire dermis shows irregularly arranged collagen bundles like a stratum spongiosum. Before egg laying, the skin swells, primarily by thickening and further by loosening of the middle zone of the dermis. In the epidermis, large furrows develop that are the prospective sites of egg nidation. The epidermis, which forms a brood chamber around the developing egg becomes bi‐layered and very thin and lacks a stratum corneum. Further, the dermis loosens and becomes heavily vascularized. Egg carrying females do not have mature oocytes in their ovaries indicating a slow down or interruption of egg maturation during this period. Similarities with the brood pouch of marsupial frogs are discussed. J. Morphol., 2009. © 2009 Wiley‐Liss, Inc.