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PubMed2004

Transcriptional immune responses by honey bee larvae during invasion by the bacterial pathogen, Paenibacillus larvae.

Honey bee larvae are highly susceptible to the bacterial pathogen Paenibacillus larvae only during the first instar of larval development. Transcript levels were measured for genes encoding two antimicrobial peptides, abaecin and defensin, as well as for two candidates in the immune response cascade (PGRP-LD and masquerade) in control larvae and larvae exposed to the pathogen. Transcripts for all four are present throughout development. This suggests that other physiological or dietary factors may better explain the age-based change in vulnerability to this pathogen. One of these genes, abaecin, shows significant up-regulation 24 h following oral inoculation with P. larvae, precisely when the bacterium surmounts the midgut epithelia of bees. Expression of both antimicrobial peptides varied by 1000-fold across different nestmate bees, indicating an allelic component to their expression. The implications of these results for current hypotheses related to disease tolerance in social insects are discussed, along with implications for breeding bees resistant to this important disease.

Animals↗
PubMed1995

Development by injection in Simulium damnosum s.l. of two Onchocerca species from the wart hog to infective larvae resembling type D larvae (Duke, 1967).

Four wart hogs (Phacochoerus aethiopicus) examined in the Sudan savanna of North-Cameroon were all found infected with two types of skin microfilariae. One was O. ramachandrini Bain, Wahl and Renz, 1993, the adult worms of which live in the subcutaneous tissues of the feet. The other, smaller type belongs to a new Onchocerca species, the adult worms of which were not yet found. O. ramachandrini-microfilariae were evenly distributed across the whole body surface, those of Onchocerca sp. were concentrated on the back. The two species of microfilariae were isolated from an infected hide separated under the dissecting microscope and injected into the thorax of pupae-hatched S. squamosum and S. damnosum s.slr. females. Both filariae developed in both flies at high rates (33-47% of injected microfilariae) and without pathological forms to infective larvae L3). Both L3-species had a caudal tip, were long, slender and very motile and had a conspicuous glandular oesophagus. L3 from O. ramachandrini-microfilariae had a long glandular oesophagus (55% of total L3 length), a round head and measured an average of 955 microns long and 19.2 microns wide. L3 from the other microfilaria-species were shorter (845 microns, P < 0.001) and thinner (16.7 microns, P < 0.001) and had a shorter glandular oesophagus (36%, P < 0.001), a shorter tail (P < 0.01) and a conical head. Both L3-species, by their caudal tip, their long and slender silhouette, their great motility and their conspicuous glandular oesophagus resemble non-O. volvulus filarial L3 known, since many years, to occur in "wild" S. damnosum s.l. in Cameroon (Type D larvae, Duke, 1967) and in Liberia (Agamofilaria Type VI, Voelker and Garms, 1972). During our study, L3 such larvae were found in 12 wild S. damnosum s.l. from two geographically different areas of North Cameroon and all identified as O. ramachandrini. The excellent development of the two Onchocerca species from the wart hog in S. damnosum s.l. after artificial infection, and the identification of all recently examined wild Type D larvae as O. ramachandrini suggest that S. damnosum s.l. is a natural vector of O. ramachandrini and that most (if not all) of the Type D larvae in onchocerciasis vectors in North-Cameroon originate from wart hogs.

Animals↗
PubMed2003

Who came first--larvae or adults? origins of bilaterian metazoan larvae.

There is a classic controversy in zoology over whether the common ancestor of living bilaterian phyla was a benthic animal with a bilaterian body plan, or was a pelagic larva-like animal similar to what we see today in the primary larvae of indirect-developing bilaterians. We examine the current larva-like adult hypothesis, and present an alternate model for the evolution of complex life histories by intercalation of larval features into the ontogeny of an ancestral direct-developing bilaterian. This gradual accumulation of larval features results in a developmental regulatory program that produces a larva distinct in body plan from the adult. The evolution of a rapid and complete metamorphosis is made possible by the convergent evolution of set aside cells in the final stages of the emergence of indirect developing larval forms. Although convergences abound either hypothesis for the evolution of developmental pathways and life histories, the bilaterian first hypothesis is consistent with all stages of evolution of a complex life history being selectively advantageous, with the rapid evolution of larval forms, and with the frequent co-option of genes from the adult phase of the life cycle prevalent in the evolution of embryos and larvae.

Animals↗
PubMed1982

[The larva precipitation test with Ascaris suum and Toxocara canis larvae].

Investigations were made by means of a larvae precipitation test (LPT) on different laboratory animals (pigs and white mice, and pigs, rabbits, guinea pigs and white mice respectively) experimentally infected with Ascaris suum and Toxocara canis respectively for the serological evidence of specific A. suum and T. canis antibodies. Living A. suum larvae isolated from the lungs of experimentally infected white mice forming oral, excretion porus and cuticula precipitates proved to be a suitable antigen for the intravital evidence of prepatent A. suum infections in pigs and mice. By using living T. canis larvae from lungs, liver and brain of infected mice as antigen prepatent T. canis infections in pigs, rabbits, guinea pigs and mice were serologically proved because of precipitates on oral and excretion porus. It was found for the first time that frozen preserved larvae of A. suum and T. canis are suitable for the evidence of specific antibodies and--because of the faster and more exact determination of the results as well as the possible preserving of the antigen--superior to the test on living larvae.

Animals↗
PubMed1999

In situ localization of heat-shock and histone proteins in honey-bee (Apis mellifera l.) larvae infected with Paenibacillus larvae.

The immunohistochemical localization of the heat shock proteins (Hsp70 and Hsp90) and histone protein in healthy and Paenibacillus larvae infected honeybee (Apis mellifera L.) larvae has been studied. Hsp70 was found in the nuclei and the cytoplasm of infected midgut, salivary gland cells and haemocytes, but not in uninfected larvae. Hsp90 was localized in both infected and uninfected cells. Exposed histone proteins were localized in the nuclei of dying uninfected cells undergoing programmed cell death. The distribution of histone protein in uninfected cells of midgut, salivary gland, and other tissues was nuclear and indicative of normal programmed cell death at levels between 1 and 5%. After applying histone protein antibodies to P. larvae infected honeybee larvae, the DAB based reaction product was located in the nuclei or immediate surroundings of all larval cells. The Hsp70, Hsp90 and histone protein distribution patterns are discussed in relation to the morphological, cytochemical and immunocytochemical characteristics of programmed cell death and pathological necrosis. Results produced by methyl green-pyronin staining confirm an elevation of RNA levels in normal programmed cell death and a reduced staining for RNA in necrotic infected cells.

Animals↗
PubMedDate not supplied

Paenibacillus larvae larvae spores in honey samples from Uruguay: a nationwide survey.

American foulbrood is a severe bacterial disease affecting larvae of the honeybee Apis mellifera and it is caused by Paenibacillus larvae larvae. The disease is present worldwide and cases have been reported in almost all the beekeeping regions of the five continents. During 2001 and 2002 we carried out a nationwide study to assess the presence and amount of P. l. larvae spores in honey samples from Uruguay, combining classic bacteriological, and molecular approaches. The distribution of P. l. larvae spores in honey of the whole country showed a clear pattern and may provide useful data for a control and prevention strategy of American foulbrood.

Animals↗
PubMedDate not supplied

Brown larva: an allele of the green larva mutation in the malaria mosquito, Anopheles stephensi.

We isolated a new larval color mutant, brown larva (b), from the Bangalore, India strain of Anopheles stephensi Liston. The gene b is an autosomal recessive with uniform expression and complete penetrance. We conducted extensive crosses to establish allelism between brown larva (b) and green larva (g) reported previously in An. stephensi from our laboratory. The wild-type is dominant to green larva, which, in turn, is dominant to brown larva. These larval color mutants belong to an allelic series.

Alleles↗
PubMed2004

Biochemical characterization of different genotypes of Paenibacillus larvae subsp. larvae, a honey bee bacterial pathogen.

Paenibacillus larvae subsp. larvae (P. l. larvae) is the aetiological agent of American foulbrood (AFB), the most virulent bacterial disease of honey bee brood worldwide. In many countries AFB is a notifiable disease since it is highly contagious, in most cases incurable and able to kill affected colonies. Genotyping of field isolates of P. l. larvae revealed at least four genotypes (AB, Ab, ab and alpha B) present in Germany which are genotypically different from the reference strain DSM 7030. Therefore, based on these data, five different genotypes of P. l. larvae are now identified with genotype AB standing out with a characteristic brown-orange and circled two-coloured colony morphology. Analysing the metabolic profiles of three German genotypes (AB, Ab and ab) as well as of the reference strain using the Biolog system, a characteristic biochemical fingerprint could be obtained for each strain. Cluster analysis showed that while genotypes Ab, ab and the reference strain DSM 7030 are rather similar, genotype AB is clearly different from the others. Analysis of all isolates for plasmid DNA revealed two different plasmids present only in isolates belonging to genotype AB. Therefore, genotype AB is remarkable in all aspects analysed so far. Future analysis will show whether or not these differences will expand to differences in virulence.

Animals↗
PubMed1977

Skin penetration of infective hookworm larvae. I. The path of migration of infective larvae of Ancylostoma braziliense in canine skin.

Migratory behaviour of Ancylostoma braziliense was studied in relation to the structure of the skin in dogs after primary infections. Data were obtained studying serial sections of lateral skin areas 6 mm in diameter, which had been exposed to larvae. The sections were stained either with Harris' haematoxylin and eosin or with P.A.S. or as outlined by Crossmon. Most of the larvae managed to penetrate the skin within 1/2 hr after the application. Hairs did not seem to constitute sites of entry. The larvae moved into the horny layer where edges of keratinized cells provide uneven spots. They migrated approximately parallel to the surface from the horny layer into the living epidermis and continued into an external root sheath of a hair follicle. They could only leave this site via sebaceous glands for the dermis or via apocrine sweat glands for the hypodermis. Tunnels from the epidermis into the dermis, however, suggested that a direct trans-epidermal migration had occurred. The vessels invaded by larvae were hypodermal lymphatic vessels. The first ones were found in these structures 1/2 h after the onset of the exposure.

Ancylostoma↗
PubMed2005

Phenoloxidase in larvae of Plodia interpunctella (Lepidoptera: Pyralidae): molecular cloning of the proenzyme cDNA and enzyme activity in larvae paralyzed and parasitized by Habrobracon hebetor (Hymenoptera: Braconidae).

Phenoloxidase (PO) is a major component of the insect immune system. The enzyme is involved in encapsulation and melanization processes as well as wound healing and cuticle sclerotization. PO is present as an inactive proenzyme, prophenoloxidase (PPO), which is activated via a protease cascade. In this study, we have cloned a full-length PPO1 cDNA and a partial PPO2 cDNA from the Indianmeal moth, Plodia interpunctella (Hubner) (Lepidoptera: Pyralidae) and documented changes in PO activity in larvae paralyzed and parasitized by the ectoparasitoid Habrobracon hebetor (Say) (Hymenoptera: Braconidae). The cDNA for PPO1 is 2,748 bp and encodes a protein of 681 amino acids with a calculated molecular weight of 78,328 and pI of 6.41 containing a conserved proteolytic cleavage site found in other PPOs. P. interpunctella PPO1 ranges from 71-78% identical to other known lepidopteran PPO-1 sequences. Percent identity decreases as comparisons are made to PPO-1 of more divergent species in the orders Diptera (Aa-48; As-49; and Sb-60%) and Coleoptera (Tm-58; Hd-50%). Paralyzation of host larvae of P. interpunctella by the idiobiont H. hebetor results in an increase in phenoloxidase activity in host hemolymph, a process that may protect the host from microbial infection during self-provisioning by this wasp. Subsequent parasitization by H. hebetor larvae causes a decrease in hemolymph PO activity, which suggests that the larval parasitoid may be secreting an immunosuppressant into the host larva during feeding.

Amino Acid Sequence↗
PubMed1977

The free swimming Pipa larvae, with a review of pipid larvae and pipid phylogeny (Anura: Pipidae).

This paper describes the morphology of the free swimming Pipa larvae, compares them with Xenopus, Hymenochirus, and to some extent, Rhinophrynus larvae, and presents a morphological diagnosis of pipid larvae. Pipa and Xenopus have very similar chondrocrania. Hymenochirus is superficially different but has the same diagnostic features. The differences appear related to its small size and predatory habitus. Other aspects of anatomy, especially the filter apparatus are very different in each genus. The filter apparatus of Pipa is somewhat reduced and seems modified for the retention of relatively large (20+ microns) particles. Similar adaptations may have been annectant to predations in Hymenochirus, which lacks a filter apparatus. However, varying states of seven character complexes, which cut across the varying ecology, show that there are two basic pipid lineages, each currently confined to Africa or South America, respectively. Recent finds of fossil South American Xenopus indicate that these two lineages separated before the continents did. This does not warrant the recognition of two subfamilies because Xenopus and Hymenochirus are too different. Pseudhymenochirus is not an intermediate between them; it is primitive Hymenochirus. Eight character states separate pipid and rhynophrynid larvae.

Animals↗
PubMed1985

The distribution of the infective larvae of sheep gastro-intestinal nematodes in soil and on herbage and the vertical migration of Trichostrongylus vitrinus larvae through the soil.

From May 1982 until September 1983 samples of soil and herbage were collected from a paddock grazed from May to October 1982, and for two short periods between May and July 1983, by sheep infected with gastro-intestinal nematodes. Few infective larvae were recovered from the soil although appreciable numbers of larvae were recovered from the herbage. Infective larvae of Trichostrongylus vitrinus in faeces buried in the soil of grass plots, at a depth of 10 cm, each month from April 1982 until March 1983, migrated on to the herbage at all times of the year, few remaining in the soil. The significance of the soil as a reservoir of infective larvae is discussed.

Animals↗
PubMed1997

Oviposition responses of Aedes aegypti and Ae. atropalpus (Diptera: Culicidae) females to waters from conspecific and heterospecific normal larvae and from larvae infected with Plagiorchis elegans (Trematoda: Plagiorchiidae).

Ovipositing Aedes aegypti (L.) females were attracted to waters in which uninfected Aedes atropalpus (Coquillett) larvae had been reared, but were repelled by waters from larvae of either species infected with the entomopathogenic digenean Plagiorchis elegans (Rudolphi). In contrast, Ae. atropalpus females were attracted to or repelled by waters from conspecific uninfected and infected larvae, respectively, but did not respond to corresponding waters from Ae. aegypti larvae. The sensitivity of ovipositing females of both species to repellents and attractants is discussed in terms of possible selective pressures exerted by unstable breeding environments.

Aedes↗
PubMed1998

Immunological studies on the settlement-inducing protein complex (SIPC) of the barnacle Balanus amphitrite and its possible involvement in larva-larva interactions.

Immunological investigation has revealed that a settlement-inducing protein complex (SIPC), which induces cypris settlement of the barnacle Balanus amphitrite, is synthesized during larval development and accumulates in the cypris larva. We previously purified the SIPC from adult B. amphitrite, which was active when bound to a substratum. The SIPC is a glycoprotein of high molecular mass, consisting of three major subunits of 76, 88 and 98 kDa with lentil lectin (LCA)-binding sugar chains. In the present study, we prepared antiserum against each LCA-binding subunit of SIPC, and performed immunoblot analyses. Immunoblotting of adult extracts showed that anti-76-kDa antibody reacted only with the 76-kDa protein, whereas anti-88-kDa and anti-98-kDa antibodies reacted with both the 88-kDa and the 98-kDa proteins. Immunoblotting of larval extracts indicated that reactivity of the 76-kDa protein to anti-76-kDa antiserum increased during larval development and cyprid extracts reacted strongly. Moreover, by using immunostaining we found that the SIPC was contained in 'footprints' of cyprids, which have been shown to act as a settlement-inducing pheromone, and is secreted onto the antennular attachment discs. The results suggest that the SIPC (or SIPC-like proteins) is involved in both adult-larva and larva-larva interactions during settlement of the barnacle B. amphitrite.

Animals↗
PubMed2005

Strain- and genotype-specific differences in virulence of Paenibacillus larvae subsp. larvae, a bacterial pathogen causing American foulbrood disease in honeybees.

Virulence variations of Paenibacillus larvae subsp. larvae, the causative agent of American foulbrood disease of honeybees, were investigated by analysis of 16 field isolates of this pathogen, belonging to three previously characterized genotypes, as well as the type strain (ATCC 9545) of P. larvae subsp. larvae, with exposure bioassays. We demonstrated that the strain-specific 50% lethal concentrations varied within an order of magnitude and that differences in amount of time for the pathogen to kill 100% of the infected hosts (LT100) correlated with genotype. One genotype killed rather quickly, with a mean LT100 of 7.8 +/- 1.7 days postinfection, while the other genotypes acted more slowly, with mean LT100s of 11.2 +/- 0.8 and 11.6 +/- 0.6 days postinfection.

Animals↗
PubMed2002

[Studies on chemotactic behaviors of Strongyloides ratti infective larvae in vitro and migration routes of the larvae in rat head].

For the purpose of clarifying host-finding mechanisms, the infective larvae of Strongyloides ratti were run on an agarose plate which had been placed various attractants around the larvae. They were accumulated at the sites of sodium compounds, serum proteins and albumins. At 20, 30, 40 hours after infection, rats were killed and heads were separated. They were then processed for thin section specimens. Larvae were found in brains, olfactory bulbs and its nerves. These larvae seemed to move along olfactory nerves during descending from the cranial cavity. Another migration study was done by whole body autoradiography after 35S-methionine labeling for clarifying the larval pathway how to invade cranial cavity in the rats. They first crawled under subcutaneous region of rat and then accumulated at the tip of the nose. Next, they began to ascend olfactory nerves. They were in cranial cavity up to 20 hours after infection and then descending same route to nasal cavity. I don't know why they aim the cranial cavity but they had necessity to invade the cranial cavity and stay there for appropriate time to be an adult in the intestine.

Animals↗
PubMed1990

Scanning electron microscopy of the sheathed infective larva and parasitic third-stage larva of Haemonchus contortus (Nematoda: Trichostrongyloidea).

Scanning electron microscopy was used to describe the infective and parasitic third-stage larvae of Haemonchus contortus, the large stomach worm of ruminants. Infective larvae are ensheathed in the cuticle of the second stage, so the descriptions are of the second- and third-stage cuticles. Both larval stages had an inner circle of 6 labial papillae, an outer circle of 6 labial papillae and 4 somatic papillae, and lateral amphidial pits. Infective larvae (cuticle of the second stage) had the 6 internal labial papillae on prominent bluntly rectangular lappets in a star-shaped arrangement around a large triradiate mouth, small triangular or round amphidial pits, flattened ribbonlike lateral alae, and phasmidial apertures opening on the ventral surface of the lateral alae. Parasitic third-stage larvae had the 6 internal labial papillae on small elevations without lappets around a small mouth; large, oval amphidial pits; ribbonlike lateral alae for most of their length, but with the anterior 30-40 microns of the alae cordlike; and phasmidial apertures on the body cuticle ventral to the lateral alae.

Animals↗
PubMed1998

Characterization of isolates of Paenibacillus larvae subsp. larvae from diverse geographical origin by the polymerase chain reaction and BOX primers.

Ninety-nine strains of Paenibacillus larvae subsp. larvae, the causal agent of American Foulbrood disease (AFB) of honeybees, were isolated from different regions of Argentina and other countries. The isolates were characterized on the basis of DNA fingerprints by a polymerase chain reaction technique (PCR) with BOX sequence-specific primers. Isolates from Argentina generated three groups of patterns (designated A, B, and C), while P. larvae subsp. larvae strains obtained from other countries yielded two distinguishable patterns (coincident with A and B). Strains from U.S. A. and Germany were identical and related to Group A, while all Czech and English isolates belonged to Group B. Strains from France, Poland, Italy, Sweden, and New Zealand showed two different patterns (A and B). Comparisons of the biochemical type and genotype of isolates rendered no obvious linkage between both features. These results suggest that AFB in Argentina resulted from multiple sources of contaminated material.

Animals↗