Absorption of experimentally administered materials by the hepatopancreas cells of the crayfish, Procambarus clarki

After long term starvation, the crayfish, Procambarus clarki was administered protein silver, iron lactate and olive oil, and its hepatopancreas was subsequently examined by electron microscopy. The reserve cells showed changes suggesting the absorption of these materials from the acinar lumen had taken place. In contrast, the hindgut of crayfish seemed to have no absorptive ability. In crustaceans the hepatopancreas is the largest gland in the body. The chief functions of this gland are the secretion of digestive juice into the stomach and absorption of digested food. It is also where materials which are necessary for hardening of animals that have undergone ecdysis are stored. Although these roles are commonly accepted, the absorptive ability of the gland has been rarely studied. Yonge (1924) and van Weel (1955) attempted to obtain evidence for the absorptive function of hepatopancreas cells of Nephrops norvegicus and Atya spinides using iron lactate and iron saccharate, and obtained some positive results. They used the histochemical Prussian blue test to demonstrate absorbed iron. Vonk (1960) referred to the results of a few authors who had tried to show fat deposits in reserve cells of the hepatopancreas after the administration of olive oil to the animals. But because starvation did not affect the quantity of stored fat in the hepatopancreas cells, the attempt failed to reveal the absorption of fat by the hepatopancreas. In the present paper, the authors describe the results of studies on the absorption of experimentally administered materials by hepatopancreas cells of the crayfish, Procambarus clarki, using electron microscopy.     

Genetic variation and differentiation in Armadillidium vulgare (Isopoda: Oniscoidea)

Genetic variation was examined with polyacrylamide and starch gel electrophoresis at 22 loci in 8 populations of Armadillidium vulgare. Polymorphism was observed at 9 loci, and the average heterozygosity was 3.0%. Heterozygosity was low when compared to most invertebrates but was similar to that reported for certain decapods. A significant heterozygote deficiency occurred in most populations of A. vulgare and considerable genetic differentiation was observed among isopod populations.     

Preparation of an active recombinant peptide of crustacean androgenic gland hormone

In crustaceans, male sexual characteristics are induced by a hormone referred to as androgenic gland hormone. We have recently cloned a candidate cDNA in the terrestrial isopod Armadillidium vulgare. In order to prove that this cDNA encodes the hormone, recombinant single-chain precursor molecules consisting of B chain, C peptide and A chain were produced using both baculovirus and bacterial expression systems. Neither recombinant precursors showed activity. Digestion of only the precursor carrying a glycan moiety with lysyl endopeptidase gave a heterodimeric peptide with hormonal activity by removing a part of C peptide. These results indicate that the cDNA encodes the hormone.     

Immunological identification of crustacean androgenic gland hormone, a glycopeptide

Androgenic gland hormone (AGH) is known to be responsible for sex differentiation in crustaceans. The amino acid sequence of AGH-active fraction purified from androgenic glands of the terrestrial isopod Armadillidium vulgare was determined by immunoprecipitation employing three types of antibodies raised against differing parts of the amino acid sequence deduced from the putative AGH cDNA sequence. As all antibodies adsorbed AGH activity, it was confirmed that the sequence examined was that of AGH. The affinity of AGH to certain lectins indicated that AGH possesses a carbohydrate moiety, which is in agreement with the observation that AGH possesses an N-glycosylation consensus sequence.     

Mitochondrial genome haplotype hypervariation within the isopod parasitic nematode Thaumamermis cosgrovei

Characterization of mitochondrial genomes from individual Thaumamermis cosgrovei nematodes, obligate parasites of the isopod Armadillidium vulgare, revealed that numerous mtDNA haplotypes, ranging in size from 19 to 34 kb, are maintained in several spatially separated isopod populations. The magnitude and frequency of conspecific mtDNA size variation is unprecedented among all studied size-polymorphic metazoan mitochondrial genomes. To understand the molecular basis of this hypervariation, complete nucleotide sequences of two T. cosgrovei mtDNA haplotypes were determined. A hypervariable segment, residing between the atp6 and rrnL genes, contributes exclusively to T. cosgrovei mtDNA size variation. Within this region, mtDNA coding genes and putative nonfunctional sequences have accumulated substitutions and are duplicated and rearranged to varying extents. Hypervariation at this level has enabled a first insight into the life history of T. cosgrovei. In five A. vulgare hosts infected with multiple nematodes, four carried nematodes with identical mtDNA haplotypes, suggesting that hosts may become infected by ingesting a recently hatched egg clutch or become parasitized by individuals from the same brood prior to dispersal of siblings within the soil.     

Granivory in terrestrial isopods

Abstract Granivory (seed feeding) evolved in many animal groups. Field observations hint at the existence of granivory in terrestrial isopods (Crustacea: Isopoda: Oniscidea), for which it was previously unknown. In this paper granivory in terrestrial isopods is addressed for the first time, focusing on (i) seed acceptance in the presence of plant litter and (ii) size as a constraint for acceptance and consumption. In a laboratory choice experiment, Armadillidium vulgare consumed seeds of Capsella bursa‐pastoris and Poa annua when plant litter was present. In a no‐choice experiment, seeds of seven plant species were offered to four isopod species giving 13 combinations in total [A. vulgare (seven species of seeds), Oniscus asellus (two), Porcellio scaber (two), and Porcellionides pruinosus (two)]. The tested isopods differed in their acceptance (proportion of individuals consuming seeds) and consumption (both number and amount of seeds eaten) of seed species. Size as a constraint was demonstrated in A. vulgare offered Cirsium arvense seed, since the probability that this large seed was eaten increased with body size of the isopod. In the other 10 seed–isopod pairs, seed consumption increased linearly with isopod body size. Granivory is thus widespread in terrestrial isopods, although the tendency to eat seeds differs between species.     

Novel structures in secreting the androgenic gland hormone

The secretory granules in the androgenic gland of the terrestrial isopod Armadillidium vulgare, which have been indistinct for long time because of vulnerable structures, were revealed by using the rapid-freezing and freeze-substitution method. The fine structure of the androgenic gland is conspicuous by the distribution of numerous particular organelles in the cytoplasm consisting of the endoplasmic reticulum and the Golgi complex, and by having a number of highly organized structures developed between the androgenic gland cells. The structures connect to the intercellular space, which is seen as intercellular canaliculi for exporting the androgenic gland hormone. The plasma membranes near the particular structure of the intercellular canaliculi in the androgenic gland are often specialized to form cellular junctions. The secretory granules including the electron-dense materials, which are supposed to be peptides of androgenic gland hormone, are distributed beside the particular structure of the intercellular canaliculi. Some of the granules are seen to fuse with the plasma membranes. This observation suggests that, in the Armadillidium vulgare, the secretory granules containing androgenic gland hormone are transferred to the extracellular space through the intercellular canaliculi particularly developed for exporting the peptide hormone. This is the first evidence to show the secretory mechanism of the androgenic gland hormone in the Isopoda.     

Ommochrome deficiency in an albino strain of a terrestrial isopod, Armadillidium vulgare.

In order to clarify the cause of ommochrome deficiency in an albino strain of the terrestrial isopod, Armadillidium vulgare, levels of xanthommatin, 3-hydroxykynurenine, 3-hydroxyanthranilic acid and tryptophan in whole body extracts of the albino and the wild type individuals were determined together with enzyme activities of kynurenine-3-hydroxylase, kynureninase and tryptophan-2,3-dioxygenase. Xanthommatin could not be detected in the albinos. The levels of 3-hydroxykynurenine and 3-hydroxyanthranilic acid were determined by high-performance liquid chromatography (HPLC) with electrochemical detection and were markedly low in the albinos compared with the wild type individuals. In contrast to those, the tryptophan levels determined by HPLC with fluorescence detection did not differ significantly between the two phenotypes. In the albino A. vulgare, kynurenine-3-hydroxylase activity was lower and kynureninase activity was higher than in the wild type, although the differences were not statistically significant. Tryptophan-2,3-dioxygenase activity in the albinos was less than 10% that in the wild type. Thus, ommochrome deficiency in the albino A. vulgare is considered to be caused by the extremely low activity of tryptophan-2,3-dioxygenase.     

Cation regulation by the terrestrial isopod Armadillidium vulgare (Crustacea: Isopoda: Oniscidea) during dehydration in air

Many terrestrial arthropods display tight osmotic and ionic regulation of the hemolymph during dehydration. In this study, we sought to quantify the level of regulation of the major hemolymph cations in the terrestrial isopod Armadillidium vulgare (Isopoda, Oniscidea). Inulin space measurements showed that the hemolymph comprises 52 ± 2.2% of the hydrated water content but contributes 71 ± 9.8% of water losses during desiccation. Hemolymph concentrations of Na+, K+ and Ca2+ were measured in variably dehydrated animals using ion-selective microelectrodes and compared with predicted concentrations assuming no regulation. Na+ and Ca2+ are quite tightly regulated, showing respective concentration increases of 20.8% and 7.1% following a 50% reduction in hemolymph volume, but K+ showed no measurable regulation. The excreted cation fraction during desiccation is negligible. Sites of ion sequestration were examined by injecting 22Na and ??Ca into the hemolymph of hydrated animals and assaying tissue-specific activities following dehydration. Na+ is apparently sequestered non-specifically by an unknown mechanism. Ca2+ accumulates in the dorsal somatic tissues, possibly in the calcium pool of the cuticle. How A. vulgare avoids significant disruptions of E(m) and neuromuscular function in the absence of K+ regulation, and how it sequesters Na+, both pose intriguing challenges for future work.     

Organization of the large mitochondrial genome in the isopod Armadillidium vulgare.

The mitochondrial DNA (mtDNA) in animals is generally a circular molecule of approximately 15 kb, but there are many exceptions such as linear molecules and larger ones. RFLP studies indicated that the mtDNA in the terrestrial isopod Armadillidium vulgare varied from 20 to 42 kb. This variation depended on the restriction enzyme used, and on the restriction profile generated by a given enzyme. The DNA fragments had characteristic electrophoretic behaviors. Digestions with two endonucleases always generated fewer fragments than expected; denaturation of restriction profiles reduced the size of two bands by half; densitometry indicated that a number of small fragments were present in stoichiometry, which has approximately twice the expected concentration. Finally, hybridization to a 550-bp 16S rDNA probe often revealed two copies of this gene. These results cannot be due to the genetic rearrangements generally invoked to explain large mtDNA. We propose that the large A. vulgare mtDNA is produced by the tripling of a 14-kb monomer with a singular rearrangement: one monomer is linear and the other two form a circular dimer. Densitometry suggested that these two molecular structures were present in different proportions within a single individual. The absence of mutations within the dimers also suggests that replication occurs during the monomer phase.     

Partial characterization of vitellin and localization of vitellogenin production in the terrestrial isopod, Armadillidium vulgare

Vitellins were purified separately from ovaries and eggs of the isopod, Armadillidium vulgare. Ovarian vitellin consisted of at least six proteins with relative molecular masses of 205, 200, 185, 180, 122 and 112 kDa. The larger four proteins disappeared in eggs within a week after oviposition and a 59-kDa protein appeared thereafter. The amino-terminal amino acid sequences of these vitellin proteins were identical except for the ovarian 112 kDa, egg 112 kDa and 59 kDa proteins, and showed considerable similarity to those of known vitellogenins from other animals. Comparison of tryptic peptide maps of the 122 and 112 kDa proteins from eggs on reversed-phase HPLC and sequence identification of two randomly selected peaks having the same retention times indicated that two peptides were mostly similar in sequence. PCR-assisted cloning of the 5' region of a cDNA (591 bp) encoding vitellogenin revealed the presence of a signal peptide consisting of 16 amino acid residues and clarified the structural relationship among the protein components except for the ovarian 112 kDa and the egg 59 kDa proteins. Northern blot analysis revealed that the fat body is the main vitellogenin producing organ.     

Characterization and cDNA cloning of androgenic gland hormone of the terrestrial isopod Armadillidium vulgare.

The sex differentiation in crustaceans is known to be controlled by a peptide hormone called androgenic gland hormone (AGH). AGH was extracted and purified from the androgenic glands (AGs) of the male isopod Armadillidium vulgare by high-performance liquid chromatography. AGH consisted of two peptide chains and their N-terminal amino acid sequences were determined. A cDNA encoding AGH was cloned by PCR and sequenced. The cDNA had an open reading frame of 432 bp, which encoded a preproAGH consisting of a signal peptide (21 residues), B chain (44 residues), C peptide (46 residues), and A chain (29 residues). Through processing, the A and B chains might form a heterodimer interlinked by disulfide bonds. The A chain possessed a putative N-linked glycosylation site. A Northern blot analysis using the cDNA as a probe detected a hybridization signal with 0.8 kb in the RNA preparation only from the AGs.     

Energetics of isopod populations in a forest of central Japan

Energetics of the populations of three isopods, Armadillidium vulgare, Porcellio scaber and Ligidium japonicum were studied in a warm-temperate evergreen broadleaved forest of Mt. Kiyosumi in central Japan. The study deals with age composition, survivorship curves, relations of body size to number of eggs or young, and mean growth curves of the populations. Respiratory rates, calorific values and food consumptions of the individual animals were determined in the laboratory. Population density of A. vulgare was highest of the three species, being about 350/m² in June 1966. The survivorship curve of the L. japonicum population was more close to L-type than the others. Average total biomass for populations of A. vulgare, P. scaber and L. japonicum were 3.3 kcal/m², 0.67 kcal and 0.43 kcal on the monthly basis, respectively. The energy of 35.2 kcal/m² was estimated to be assimilated by the A. vulgare population, 7.84 kcal by P. scaber and 6.91 kcal by L. japonicum during the period from October 1965 to September 1966. The relations between assimilation A and production P for fish, grasshopper and isopod populations were found to be expressed as A=aP^b. The values of the constant a for the fish, grasshopper and isopod populations seem to be in the range from 10 to 25, from 2 to 7 and from 4 to 8, respectively. Production efficiencies presented as P/A of A. vulgare, P. scaber and L. japonicum populations were estimated as 19.1%, 15.3% and 13.1%, respectively. The ecological efficiency represented as M/C of these isopod populations was estimated to be in the range from 7.6% to 11. 2%. Reproduction efficiency (Rp/P) of L. japonicum population was 20%, being the highest value of the three isopod species. This may be related to the L-type survivorship curve of L. japonicum population. Reproduction efficiency, relating closely to the age structure of the population, is important in the investigation of populations of animals, particularly those that have long life span.     

Sheltering behavior of terrestrial isopods in grasslands

Abstract. The hypotheses that the sheltering behavior of four species of terrestrial isopods varies in relation to differences in their morphological, physiological, and behavioral adaptations to the terrestrial environment were tested using artificial refugia together with independent estimates of density to derive an index of sheltering activity. (1) Porcellio scaber sheltered significantly more than Platyarthrus hoffmannseggi, Armadillidium vulgare , or Philoscia muscorum , which sheltered the least. (2) There was a decline in the sheltering index (SI) for all four species after the breeding season, continuing through to the autumn and remaining low throughout the winter. (3) Changes in the sheltering behavior of each species in relation to changes in environmental conditions were used to interpret known differences in the position and breadth of their resource utilization curves along a gradient of rabbit grazing intensity. (4) Porcellio scaber sheltered more where the soil was more calcareous, P. muscorum more under the shade of trees, and both P. muscorum and A. vulgare more in grazed than in ungrazed swards. (5) Sheltering behavior was found to be positively correlated to both rainfall and soil temperature the day before sampling for A. vulgare but negatively to rainfall for P. muscorum. There was a positive relationship between the SI for P. scaber and daily air temperature range. (6) Variations in the sheltering behavior of these four species of terrestrial isopod are discussed in the context of their foraging and digestive strategies and in relation to their morphological, physiological, and behavioral adaptations to the terrestrial environment.     

A mitotic recombination in Wilms tumor occurs between the parathyroid hormone locus and 11p13

Summary Wilms tumor is believed to occur as the result of two mutations affecting both alleles of a critical gene located within the p13 band of chromosome 11 (Knudson and Strong 1972; Riccardi et al. 1978). Several mechanisms by which these mutations occur have already been determined in retinoblastoma (Cavenee et al. 1983) and Wilms tumor (Koufos et al. 1984; Orkin et al. 1984; Reeve et al. 1984; Fearon et al. 1984a; Eccles et al. 1984). Of the various mechanisms, however, no example of a mitotic recombination was demonstrated in Wilms tumor. An example is presented here which has been detected by the use of restriction fragment length polymorphisms (RFLPs) mapping to chromosome 11p. In addition the data presented are consistent with the mapping location of parathyroid hormone (PTH) being proximal to 11p13.     

Photoperiodism and seasonal breeding in aquatic and terrestrial Eumalacostraca

Summary

Seasonal reproduction in Crustacea is synchronized by environmental cues (e.g., temperature and photoperiod). Two types of responses occur: (1) in reptant decapods, short photoperiods and low temperatures are necessary to induce vitellogenesis; (2) in natant decapods and in most peracarids, both high temperatures and long photoperiods promote the onset of reproduction. In this context studies on the biological clocks involved in photoperiodic time measurement were performed on two crustaceans: the ditch shrimp Palaemonetes varians and the woodlouse Armadillidium vulgare, which is distributed worldwide outside polar and intertropical areas. The most important feature of the photoperiodic response curves was the same mean lag time in response to photophase length ≤ 12 h: short photophases delayed breeding but did not prevent it (i.e., “short-day effect”). On the contrary, long photophases promoted the onset of reproduction (i.e., “long-day effect”) differently in P. varians and A. vulgare. In A. vulgare strains the shape of the photoperiodic response curve depended on latitudinal origin. Results of “resonance” experiments provided evidence of involvement of an endogenous circadian component in the photoperiodic clocks of the two species according to the internal coincidence model developed for insects. Seeing that relations between reproduction and moulting were different in the two species, we proposed the hypothesis of an evolutionary change in the transition from the sea to the continental environment.     

The Trace Fossil Diplopodichnus from the Lower Jurassic Lacustrine Sediments of Central China and the Isopod Armadillidium vulgare (Pillbug) Lebensspuren as its Recent Analogue

The trace fossil Diplopodichnus isp. was identified in lacustrine siliciclastics of the Lower Jurassic Anyao Formation in the Henan Province, central China. This is the youngest occurrence of this ichnogenus. It is similar to some variants of recent surface traces of the isopod Armadillidium vulgare (pillbug) crawling on soft mud in temporal puddles. Therefore, isopods are suggested to be producers of the described Diplopodichnus isp. It seems that isopods should be taken into account as important component of deep lacustrine ecosystems by the Early Jurassic.     

Der Einfluß der Ernährung auf die Ultrastruktur der großen Zellen in den Mitteldarmdrüsen terrestrischer Isopoda (Armadillidium vulgare,Porcellio scaber)

Zusammenfassung Im Verlauf von 10wöchigem Nahrungsentzug unterliegen die großen Zellen der Mitteldarmdrüsen von Armadillidium vulgare und Porcellio scaber ultrastrukturellen Veränderungen, die denen entsprechen, welche von Ligia oceanica beschrieben wurden.Wiederfütterung mit verschiedenem Futter nach 6wöchigem Nahrungsentzug hat sehr verschiedene ultrastrukturelle Veränderungen zur Folge: Die dominierenden Merkmale sind Glykogen-Felder nach Saccharose-Gabe, elektronendichte Grana und große Vakuolen nach Protein, Lipideinschlüsse nach Butter und Fettkörper von Käferlarven sowie Sambucus-Blättern, Heterolysosomen nach Buchenlaub und Douglasien-Nadeln und elektronendichte Grana nach Bakterien (z.B. Bacillus subtilis). Das vielfältigste Bild zeigen die Zellen der Tiere, welche künstliches Nährmedium aufgenommen hatten.

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The influence of different diets on the ultrastructure of the large cells in the hepatopancreas of land-dwelling isopods (Armadillidium vulgare, Porcellio scaber)

Summary Over a 10-week period of food deprivation the large epithelial cells of the hepatopancreas of Armadillidium vulgare and Porcellio scaber undergo ultrastructural changes that correspond to the conditions described previously from Ligia oceanica. Refeeding with different diets after a starvation period of 6 weeks results in very different ultrastructural aspects of the large epithelial cells. The dominant features are as follows: glycogen deposits (after a sucrose diet), electron dense granules and large vacuoles (protein diet), lipid droplets (butter, fat body of beetle larvae, litter of Sambucus), heterolysosomes (litter of Fagus, needles of Pseudotsuga), and electron dense granules (bacteria, e.g. Bacillus subtilis). The most diversified ultrastructure was obtained 2 days after refeeding with an artificial diet.

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Unterstützt durch die Deutsche Forschungsgemeinschaft (DFG Sto 75/4-7)