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PubMed2006

Modelling parasitism and predation of mosquitoes by water mites.

Parasitism and predation are two ecological interactions that can occur simultaneously between two species. This is the case of Culicidae (Insecta: Diptera) and water mites (Acari: Hydrachnidia). The larva mites are~parasites of aquatic and semiaquatic insects, and deutonymphs and adults are predators of insect larvae and eggs. Since several families of water mites are associated with mosquitoes there is an interest in the potential use of these mites as biological control agents. The aim of this paper is to use mathematical modelling and analysis to assess the impact of predation and parasitism in the mosquito population. We propose a system of ordinary differential equations to model the interactions among the larval and adult stages of mosquitoes and water mites. The model exhibits three equilibria: the first equilibrium point corresponds to the state where the two species are absent, the second one to the state where only mosquitoes are present (water mites need insects to complete their life cycle), and the third one is the coexistence equilibrium. We analyze conditions for the asymptotic stability of equilibria, supported by analytical and numerical methods. We discuss the different scenarios that appear when we change the parasitism and predation parameters. High rates of parasitism and moderate predation can drive two species to a stable coexistence.

Algorithms↗

PubMedDate not supplied

Continuous cell lines from the common white, Pieris rapae crucivora Boisduval.

Three continuous cell lines, NIAS-PRC-819A, NIAS-PRC-819B, and NIAS-PRC-819C, were established from the pupal ovaries of the common white, Pieris rapae crucivora Boisduval (Insecta, Lepidoptera, Pieridae). The primary culture was initiated as explant cultures with ovariole fragments in MGM-464 medium supplemented with 20% fetal bovine serum at 25 degrees C. About 6 mo after the culture was set up, the first subculture was prepared. Thereafter, cells were subcultured with decreasing passage intervals, resulting in a cell population that multiplied continuously. The karyotypes of these cell lines were similar to each other, and the majority of the cells showed about 100 microchromosomes. The population-doubling times of these cell lines were 3 to 7 d. The cell lines were susceptible to a microsporidia, Nosema bombycis. Immunodiffusion experiments proved that these cell lines derived from the common white and not from other cell lines by contamination.

Animals↗

PubMed1983

Mg2+-dependent compactness of heterochromatic chromosome segments.

The stability of heterochromatic blocks in pachytene chromosomes of Tenebrio molitor (Insecta, Coleoptera) was analysed at the chromosomal level using a modified Miller spreading technique. Incubation of nuclei in solutions of different ionic strength and composition revealed that the characteristic compactness of heterochromatic segments was preserved in the presence of at least 0.6 mM MgCl2. The compactness of these segments was lost in solutions of different ionic strength and composition revealed that the characteristic compactness of heterochromatic segments was preserved in the presence of at least 0.6 mM MgCl2. The compactness of these segments was lost in solutions containing NaCl (0.1-100 mM), but no MgCl2. They then resembled the euchromatic segments. The decondensed heterochromatic segments could be recompacted by adding MgCl2 to a final concentration of 1.0 mM. The characteristic compactness of heterochromatin of pachytene chromosomes therefore depends on the presence of Mg2+, but is independent of Na+.

Animals↗

PubMed1993

Calibrating the bootstrap test of monophyly.

It has been suggested that the bootstrap test of monophyly is too conservative, i.e. the test rejects the hypothesis of monophyly when it is true far too often. Here, a method called the iterated bootstrap is described which estimates by randomization the probabilities associated with rejecting the hypothesis of monophyly when it is true and accepting the hypothesis of monophyly when it is false. Using this method, the bootstrap test can be calibrated by taking account of the errors associated with the hypothesis test. This method is applied to the high-level phylogeny of the Platyhelminthes using 18S rRNA sequences. The analysis suggests that the data cannot unequivocally resolve the placement of the Platyhelminthes with respect to the Annelida and Insecta.

Animals↗

PubMed1996

A new method for double immunolabelling with primary antibodies from identical species.

There are several double immunolabelling methods but each has its drawbacks. More often than not, antibodies with the required specificities are available in only one species and their use normally produces false labels due to cross-reactivity. We describe a new and reliable technique for staining with primary antibodies from the same species, that can even be employed on tissues of the donor species. The protocol avoids cross-reactivities without loss in sensitivity, uses commercially available reagents and takes advantage of enzymatic detection, although it can be adapted for fluorescent labelling. Briefly, tissue is incubated with one primary antibody, followed by a peroxidase-coupled secondary antibody which is detected using amino ethyl carbazol to give a red reaction product. Meanwhile, the next primary antibody is coupled in vitro to a biotinylated secondary antibody and excess binding sites quenched with normal immune serum from the same species as the primary antibody. This complex is applied to tissue and detected by the avidin-biotin/alkaline phosphatase technique using naphthol-AS-MX-phosphate/Fast Blue BB to produce a blue label. In addition to extensive controls, the reliability and broad applicability of this method has been confirmed in (1) murine skin cryostat sections to co-visualize antigen-presenting cells (MHC class II-immunoreactive; "-ir') with either antigen detecting T lymphocytes (CD4-ir) or Langerhans cells (NLDC-145-ir) and (2) locust (Insecta) abdominal ganglion paraffin sections, where it is known that immunoreactivities for octopamine and a FMRFamide-related peptide are colocalized in only one, uniquely identifiable neuron.

Animals↗

PubMed1980

Tracheal volume in the pupa of the Saturniid moth Hyalophora cecropia determined with inert gases.

Tracheal volume (VTr) was measured in pupae of the Giant silkworm moth Hyalophora cecropia (Saturniidae, Lepidoptera, Insecta) using inert gas wash-out techniques. The animal was placed in a small vessel that was continuously ventilated (rate, V) by a gas mixture containing 20% O2 in N2; the inflowing (F1) and outflowing gas fractions (FE) of the vessel could be continuously measured by a respiratory mass spectrometer. At the onset of a spiracular constriction period, which was evidenced from the FECO2 trace, the mixture was rapidly replaced by pure Ar. At the subsequent burst, the amount of N2 emerging from the animal, MN2, was calculated from V and the difference (FE--F1)N2. VTr was calculated from MN2 and the N2 concentration in the tracheal system before constriction (assumed to equal that in the ventilating gas before replacement by Ar). Measurements were repeated with N2 and Ar replacing each other. VTr average 48 microliter . g-1 (range 39 to 59) for animals of 5.8 g average body weight (range 3.4 to 9.9), when inert gas solubility in body fluids was accounted for. Both size and stage in pupal development appear to affect VTr. These values show reasonable agreement with literature data, mostly obtained by emptying the tracheal gas space by mechanical compression.

Animals↗

PubMed1985

Filipin-cholesterol complexes in plasma membranes and cell junctions of Tenebrio molitor epidermis.

The polyene antibiotic filipin combines with cholesterol in membranes to form complexes that are readily identifiable in the electron microscope. The distribution of filipin-cholesterol (FC) complexes is most easily studied by freeze-fracture. Larval epidermis of Tenebrio molitor (Insecta, Coleoptera) was maintained in vitro for 48 hr, since the electrophysiological properties of the cells are best characterized under these conditions. The cells were fixed in buffered 3.0% glutaraldehyde at RT for 15 min, transferred to fresh fixative containing 1% DMSO and filipin (final concentration; 0.5 mg/ml) for 3 hr RT. Control cells were treated in fixative containing 1% DMSO only. In freeze fracture replicas, FC complexes appear on the plasma membrane as large circular protrusions measuring 26.5 +/- 6.8 nm (x +/- s.d.) n = 50, in diameter and 17.1 +/- 2.8 nm, n = 50, in height and 11.7 +/- 2.6 nm, n = 25, in depth. Protrusions are about two times more frequent on the E face while pits are several times more frequent on the P face. FC complexes are most abundant (greater than 50/mu m2) on the basal membrane surface of the cells but are excluded from regions of hemidesmosomal plaques that anchor the cells to the basal lamina. FC complexes are also abundant on the apical surfaces of the cells where cuticle secretion occurs. In the lateral regions below the junctional belt, FC complexes are less numerous but often appear to increase in frequency in a graded fashion away from the junctional region. The septate junctions are relatively free of FC complexes except in regions where they open to form islands. These islands often contain gap junctions but the FC complexes rarely invade the particle domains of the gap junctions. Single FC complexes were seen in three out of a total of 97 gap junctions. Exposure of the epidermis to 20-hydroxyecdysone for 24 hr in vitro did not induce the appearance of FC complexes within the cell junctions.

Animals↗

PubMed1989

Degradation of bovine C3 by serine proteases from parasites Hypoderma lineatum (Diptera, Oestridae).

Purified enzymes of Hypoderma lineatum (Insecta, Oestridae), were assayed for their proteolytic activity on bovine C3 in normal cattle sera. The products of cleavage by these serine proteases (hypodermins A, B, and C), were analysed by electrophoresis in SDS polyacrylamide gels followed by immunoblotting. The enzymatic attack was initially directed at the alpha polypeptide chain by hypodermin A at a concentration of 1 micrograms/ml of serum and by hypodermin B at 5 micrograms/ml. The generated peptides differed in their molecular size from those produced during natural degradation of C3 in a control serum by physiologically relevant enzymes. Hypodermin A, at a concentration of 1 microgram/ml, also caused a cleavage of the beta chain. At 5 micrograms/ml, hypodermin A induced total degradation of the C3 molecule. Hypodermin B (5 micrograms/ml) starts splitting C3 near cleavage sites of factor I. Bovine C3 appears to be highly sensitive to hypodermins A and B in normal sera. Apparent molecular sizes and alignment of the bovine C3 cleavage products are presented schematically. Hypodermin C, a collagenolytic enzyme, had no effect on C3 in normal sera. The biological consequences for the immunopathological reactions associated with hypodermosis are discussed.

Animals↗

PubMed1994

Larva lights: a decade of photoaffinity labeling with juvenile hormone analogues.

The introduction of photoaffinity labeling into the mode of action of insect hormones and pheromones started 12 yr ago with the photoaffinity labeling of juvenile hormone binding proteins (JHBPs) from cockroaches in the laboratory of the late John K. Koeppe. Applying this technique to Manduca sexta led ultimately to a three-laboratory collaborative project that has begun to dissect the molecular basis for JH transport, metabolism, and nuclear binding and gene activation in Lepidoptera. This review provides (1) a history of the first experiments; (2) an idea of the breadth of the technique in the arthropod classes Insecta, Crustacea, and Arachnida; and (3) evidence for the depth of the technique in unearthing key details about three different types of the molecular action of JH in M. sexta.

Affinity Labels↗

PubMed2003

Identification of tryptophan and beta-carboline as paralysins in larvae of the yellow mealworm, Tenebrio molitor.

Acidic methanolic, whole body extracts of larval Tenebrio molitor (Insecta, Coleoptera) and other juvenile insects are highly toxic to adults of the same species and other species: injection causes instant paralysis to death. Referring to their dramatic effect in mature insects, the responsible compounds have been designated as "paralysins." Two paralysins have already been identified in the flesh fly, Neobellieria bullata, i.e., beta-alanine-tyrosine (BAY) and 3-hydroxykynurenine (3HK). We report here the isolation, from larval T. molitor, of two additional paralysins, respectively, the essential amino acid, tryptophan (Trp), and the saturated beta-carboline, 1,2,3,4,-tetrahydro-beta-carboline-3-carboxylic acid (THCA).

Animals↗

PubMed2005

The linear alometric relationship between total metabolic energy per life span and body mass of poikilothermic animals.

A linear relationship exists between total metabolic energy per life span PT(ls) (kJ) and body mass M (kg) of 54 poikilothermic species (Protozoa, Nematoda, Mollusca, Asteroidae, Insecta, Arachnoidae, Crustacea, Pisces, Amphibia, Reptilia and Snakes): PT(ls) = A(ls*)M(1.0838), where P (kJ/day) is the rate of metabolism and T(ls) (days) is the life span of animals. The linear coefficient A(ls*) = 3.7 x 10(5) kJ/kg is the total metabolic energy, exhausted during the life span per 1 kg body mass of animals. This linear coefficient can be regarded as relatively constant metabolic parameter for poikilothermic organisms, ranging from 0.1 x 10(5) to 5.5 x 10(5) kJ/kg, in spite of 17-degree differences between metabolic rate and body mass of animals. A linear relationship between total metabolic energy per life span and body mass of only 48 poikilothermic multicellular animals (without Protozoa) is: PT(ls) = A(ls*)M(0.9692) with linear coefficient A(ls*) = 2.34 x 10(5) kJ/kg. Since a power relationship exists between the rate of metabolism and body mass of animals of the type: P = aMk (a and k are the alometric constants), an empiric rule could be formulated, that life span is a time interval for which the total metabolic energy per life span becomes proportional to body mass of animals and power coefficient k becomes approximately 1.0.

Animals↗

PubMed2006

Cloning and characterization of a shrimp clip domain serine protease homolog (c-SPH) as a cell adhesion molecule.

Clip domain serine protease homologs (c-SPHs) are involved in various innate immune functions in arthropods such as antimicrobial activity, cell adhesion, pattern recognition, opsonization, and regulation of the prophenoloxidase system. In the present study, we cloned a c-SPH cDNA from tiger shrimp (Penaeus monodon) hemocytes. It is 1337 bp in length with a coding region of 1068 bp consisting a protein of 355 amino acid residues. The deduced protein includes one clip domain and one catalytically inactive serine protease-like (SP-like) domain. Its molecular weight is estimated to be 38 kDa with an isoelectric point of 7.9. The predicted cutting site of the signal peptide is located between Gly(21) and Gln(22). We aligned 15 single clip domain SPH protein sequences from 12 arthropod species; the identity of these clip domains is low and that of SP-like domains is from 34% to 46%. The conserved regions are located near the amino acid residues which served as substrate interaction sites in catalytically active serine protease. Phylogenetically, the tiger shrimp c-SPH is most similar to a low molecular mass masquerade-like protein of crayfish, but less similar to c-SPHs in Chelicerata and Insecta. Nested reverse transcription polymerase chain reaction (RT-PCR) revealed that c-SPH mRNA is expressed most in tissues with the highest hemocyte abundance. Antimicrobial and opsonization activities of the molecule were not detected. The expression of c-SPH mRNA in hemocytes was up-regulated at the 12-day post beta-glucan immersion. Recombinant c-SPH could significantly enhance hemocyte adhesion. The result suggests that the shrimp c-SPH protein plays a role in innate immunity.

Amino Acid Sequence↗

PubMed2005

Impact of a flood disaster on sediment toxicity in a major river system--the Elbe flood 2002 as a case study.

The ecotoxicological implications of a flooding disaster were investigated with the exceptional Elbe flood in August 2002 as an example. Sediment samples were taken shortly after the flood at 37 sites. For toxicity assessment the midge Chironomus riparius (Insecta) and the mudsnail Potamopyrgus antipodarum (Gastropoda) were exposed to the sediment samples for 28 days. For a subset of 19 sampling sites, the contamination level and the biological response of both species were also recorded before the flood in 2000. The direct comparison of biological responses at identical sites revealed significant differences for samples taken before and immediately after the flood. After flood sediments of the river Elbe caused both higher emergence rates in the midge and higher numbers of embryos in the mudsnail. Contrary to expectations the toxicity of the sediments decreased after the flood, probably because of a dilution of toxic substances along the river Elbe and a reduction in bioavailability of pollutants as a result of increasing TOC values after the flood.

Disasters↗

PubMed2004

Arthropods in dermatology.

Arthropods are important in medicine for a multitude of reasons. Their bites and stings may induce allergic reactions, ranging from annoying to life-threatening. Many arthropod products are also capable of inciting allergic responses in sensitized persons. In recent years, bites and stings have gained greater attention owing to increased concern about disease transmission. A common hypersensitivity response to arthropod bites, stings, and products is papular urticaria. This eruption occurs primarily in children, who eventually "outgrow" this disease, probably through desensitization after multiple arthropod exposures. Papular urticaria is most often caused by fleas or bedbugs, but virtually any arthropod is capable of inducing such a reaction. Two arthropod classes of medical importance are the Arachnida (spiders, scorpions, ticks, and mites) and the Insecta (lice, fleas, bedbugs, flies, bees, and ants). Animals in these two classes are probably responsible for more morbidity and mortality worldwide than are any other group of venomous creatures. In general, the diagnosis of arthropod bites and stings is dependent on maintenance of a high index of suspicion and familiarity with the arthropod fauna not only in one's region of practice, but also in the travel regions of one's patients. Learning objective At the completion of this learning activity, participants should be familiar with the clinical manifestations caused by a variety of arthropods as well as the treatment and possible sequelae of arthropod attacks.

Animals↗

PubMed2004

The MRJP/YELLOW protein family of Apis mellifera: identification of new members in the EST library.

Major royal jelly proteins (named MRJP1-5) of honeybee (Apis mellifera), yellow proteins of Drosophila, together with putative proteins found in several bacteria, form a protein family termed the MRJP/yellow family. Members of the family exert diverse physiological functions and amongst eukaryotes appear to be restricted to the order Insecta. MRJPs constitute about 90% of total protein of royal jelly, which is secreted by nurse bees to feed the queen and growing larvae. We looked for mrjp and yellow homologues in a honeybee brain expressed sequence tags (EST) library. In addition to the five mrjp cDNAs previously characterized, we found three additional cDNAs encoding novel MRJPs and importantly, two cDNAs coding for orthologues of Drosophila yellow proteins. One yellow cDNA and all three cDNAs coding for the novel MRJPs were assembled completely, the sequence of the other yellow homologue was partially assembled. The data we present here supports the view that repeated duplications and functional divergence occurred during the evolution of MRJPs in honeybees, with even closely related MRJPs appearing to perform diverse physiological functions. Conversely, yellow protein orthologues appear to be conserved and thus candidates for maintaining the former function(s) of yellow proteins.

Animals↗

PubMed2006

Hair canopy of cricket sensory system tuned to predator signals.

Filiform hairs located on the cerci of crickets are among the most sensitive sensors in the animal world and enable crickets to sense the faintest air movements generated by approaching predators. While the neurophysiological and biomechanical aspects of this sensory system have been studied independently for several decades, their integration into a coherent framework was wanting. In order to evaluate the hair canopy tuning to predator signals, we built a model of cercal population coding of oscillating air flows by the hundreds of hairs on the cerci of the sand cricket Gryllus bimaculatus (Insecta: Orthoptera). A complete survey of all hairs covering the cerci was done on intact cerci using scanning electronic microscopy. An additive population coding of sinusoid signals of varying frequencies and velocities taking into account hair directionality delivered the cercal canopy tuning curve. We show that the range of frequencies and velocities at which the cricket sensory system is best tuned corresponds to the values of signals produced by approaching predators. The relative frequencies of short (< 0.5 x 10(-3) m) and long hairs and their differing responses to oscillating air flows therefore enable crickets to detect predators in a time-frequency-intensity space both as far as possible and at close range.

Action Potentials↗

PubMed2004

Meiofauna as descriptor of tourism-induced changes at sandy beaches.

Tourism has long been considered as a 'clean industry' with almost no negative effects on the environment. This study demonstrated, in two different coastal systems (Mediterranean and Baltic), that tourism related activities are particularly affecting the sandy beach meio- and nematofauna in the upper beach zone, the specific ecotone in which many meiofauna species from both the marine and the terrestrial environment congregate. Tourist upper beaches are characterized by a lower % total organic matter (%TOM), lower densities, lower diversities (absence of Insecta, Harpacticoida, Oligochaeta, terrestrial nematodes and marine Ironidae nematodes) and higher community stress compared to nearby non-tourist locations. The %TOM was found to be the single most important factor for the observed differences in meiofauna assemblage structure at tourist versus non-tourist beaches in both the Mediterranean and the Baltic region. The free-living nematode assemblages from tourist upper zones depart significantly from expectations based on random selections from the regional nematode species pool. Furthermore upper zone assemblages are characterised by a low species diversity consisting of taxonomically closely related nematode species with r-strategist features. Generally, faunal differences between tourist and non-tourist beaches are decreasing towards the lower beach zones.

Analysis of Variance↗

PubMed2026

Uncovering hidden complexity in the Apis mellifera mitotranscriptome: a polyadenylation-centered perspective.

Mitochondrial transcription is gaining increasing attention as researchers seek to better understand the full coding potential of mitochondrial DNA (mtDNA). Emerging evidence suggests that mtDNA may encode additional elements beyond classical oxidative phosphorylation genes, pointing to a more complex transcriptional architecture than previously recognized. In this study, we explored the mitochondrial transcriptome of Apis mellifera (Insecta: Hymenoptera), with a particular focus on polyadenylation-associated features. Our analysis revealed that both sense and antisense transcripts undergo polyadenylation, although transcript abundance and poly(A) tail lengths varied markedly across mitochondrial genes. Several transcripts exhibited alternative isoforms, either extended or truncated, frequently including intergenic regions. These regions may represent functional non-coding elements or structural variants rather than conventional untranslated regions (UTRs). Interestingly, some transcripts also contained non-templated nucleotide additions particularly cytosine residues immediately upstream of the poly(A) tails. Monocistronic units that included portions of downstream intergenic regions were among the most abundantly represented, suggesting a possible regulatory role for these sequences. To experimentally validate our in silico findings, we performed RT-qPCR to assess relative gene expression and applied 3' RACE-PCR to define transcript boundaries. These approaches confirmed the presence of multiple transcript isoforms and supported the involvement of polyadenylation in shaping mitochondrial RNA diversity. Together, our findings reveal a previously underappreciated level of complexity in the A. mellifera mitochondrial transcriptome and highlight the potential regulatory significance of polyadenylation dynamics and intergenic region transcription.

Animals↗