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At least 865 records · Page 48Linked to original sources
PubMed1979

Unusual Baculovirus of the Parasitoid Wasp Apanteles melanoscelus: Isolation and Preliminary Characterization.

A baculovirus present in the female reproductive tract of the parasitoid wasp Apanteles melanoscelus has been isolated and partially characterized. Viral DNA is double stranded, circular, and of highly variable molecular weight ranging from 2 x 10(6) to 25 x 10(6); the DNA is of homogeneous density at rho = 1.694 g/ml. Acrylamide gels resolve 18 polypeptide bands in the case of purified virions; four to five of these appear in a semipurified nucleocapsid preparation. The electrophoretic profiles obtained are compared with those of two other baculoviruses.

Journal Article↗
PubMed1998

Reproductive caste determination in eusocial wasps (Hymenoptera: Vespidae).

Wasps (Vespidae) exhibit a range of social complexity, from solitary living to eusocial colonies, and thus are exemplary for studies of the evolutionary origin and maintenance of social behavior in animals. Integral to the definition of eusociality is the presence of reproductive castes, group members that differ qualitatively in their ability to reproduce in a social setting. Behavioral and morphological evidence suggests that caste determination, the developmental process by which differences in fecundity are established, occurs to a large extent before adult emergence (pre-imaginally) in many species of Vespidae, in both basal and advanced taxa within the clade (Vespinae+Polistinae), which includes most eusocial species. Pre-imaginal determination has been documented in many taxa (e.g. independent-founding Polistinae) where it was not thought to occur. Correlative and experimental studies indicate that differences in nutrition during larval development are often the basis of pre-imaginal caste determination. Pre-imaginal caste determination has important implications for the roles of subfertility and manipulation by nest mates in the evolution of eusocial behavior.

Journal Article↗
PubMed2003

Shape differences rather than size differences between castes in the Neotropical swarm-founding wasp Metapolybia docilis (Hymenoptera: Vespidae, Epiponini).

BACKGROUND: Swarm-founding epiponine wasps are an intriguing group of social insects in which colonies are polygynic (several queens share reproduction) and differentiation between castes is often not obvious. However, caste differences in some may be more pronounced in later phases of the colony cycle. RESULTS: Using morphometric analyses and multivariate statistics, it was found that caste differences in Metapolybia docilis are slight but more distinct in latter stages of the colony cycle. CONCLUSIONS: Because differences in body parts are so slight, it is proposed that such variation may be due to differential growth rates of body parts rather than to queens being larger in size, similar to other previously observed epiponines.

Animals↗
PubMed2006

Tuba stimulates intracellular N-WASP-dependent actin assembly.

Tuba is a multidomain scaffolding protein that links cytoskeletal dynamics and membrane trafficking pathways. The N-terminus of Tuba binds dynamin1, and the C-terminus contains domains that can interact with signaling pathways and cytoskeletal regulatory elements. We investigated Tuba localization, distribution and function in B16 melanoma cells. Tuba overexpression stimulated dorsal ruffles that occurred independently of dynamin function. Tuba expression induced actin-driven motility of small puncta that required the C-terminal SH3, GEF and BAR domains. Additionally, Tuba was recruited to lipid vesicles generated by overexpression of phosphatidylinositol-4-phosphate 5-kinase type Ialpha (PIP5Kalpha), localizing prominently to the head of the comets and at lower levels along the actin tail. We propose that Tuba facilitates dorsal ruffling of melanoma cells through direct interaction with actin-regulatory proteins and the recruitment of signaling molecules to lipid microdomains for the coordinated assembly of a cytoskeletal network. Knockdown of Tuba by RNA interference (RNAi) attenuated PIP5Kalpha-generated comet formation and the invasive behavior of B16 cells, implying that Tuba function is required for certain aspects of these processes. These results suggest first that Tuba-stimulated dorsal ruffling might represent a novel mechanism for the coordination of N-WASP-dependent cytoskeletal rearrangements and second that Tuba function is implicated in motility processes.

Actin-Related Protein 2-3 Complex↗
PubMed2001

The WASp-like protein scar regulates macropinocytosis, phagocytosis and endosomal membrane flow in Dictyostelium.

Scar, a member of the WASp protein family, was discovered in Dictyostelium discoideum during a genetic screen for second-site mutations that suppressed a developmental defect. Disruption of the scar gene reduced the levels of cellular F-actin by 50%. To investigate the role of Scar in endocytosis, phagocytosis and endocytic membrane trafficking, processes that depend on actin polymerization, we have analyzed a Dictyostelium cell line that is genetically null for Scar. Rates of fluid phase macropinocytosis and phagocytosis are significantly reduced in the scar- cell-line. In addition, exocytosis of fluid phase is delayed in these cells and movement of fluid phase from lysosomes to post-lysosomes is also delayed. Inhibition of actin polymerization with cytochalasin A resulted in similar phenotypes, suggesting that Scar-mediated polymerization of the actin cytoskeleton was important in the regulation of these processes. Supporting this conclusion, fluorescence microscopy revealed that some endo-lysosomes were ringed with F-actin in control cells but no F-actin was detected associated with endo-lysosomes in Scar null cells. Disruption of the two genes encoding the actin monomer sequestering protein profilin in wild-type cells causes defects in the rate of pinocytosis and fluid phase efflux. Consistent with a predicted physical interaction between Scar and profilin, disrupting the scar gene in the profilin null background results in greater decreases in the rate of fluid phase internalization and fluid phase release compared to either mutant alone. Taken together, these data support a model in which Scar and profilin functionally interact to regulate internalization of fluid and particles and later steps in the endosomal pathway, probably through regulation of actin cytoskeleton polymerization.

Actins↗
PubMed1996

Structure and function of learning flights in ground-nesting bees and wasps

Bees and wasps perform systematic flight manoevres when they leave their nest or a foodplace, during which they acquire or update their visual memory of the goal location. In a typical learning flight, the insect backs away from the goal in a series of arcs that are roughly centred on the goal. The mean rate of turning is rather constant and tends to balance the angular speed at which the arc is described. As a result, the insect views the goal at relatively fixed retinal positions in its left and right visual field, depending on flight direction. The general direction in which the insect backs away from the goal and the transition from one arc segment to the next are influenced by the local scene and by compass cues. Insects returning to the goal repeat some of the flight manoeuvres of their preceding learning flights. Their orientation in space and the retinal positions at which they view nearby landmarks are similar. One important function of learning flights appears to be the acquisition of visual depth information. We review the consequences of the structure of learning flights for visual information processing and discuss how they may relate to the acquisition of a visual representation and the task of pinpointing the goal.

Journal Article↗
PubMed1999

Venom of a parasitoid wasp induces prolonged grooming in the cockroach

The parasitoid wasp Ampulex compressa hunts cockroaches Periplaneta americana, stinging them first in the thorax and then in the head, the sting penetrating towards the subesophageal ganglion. After being stung the cockroach grooms almost continuously for approximately 30 min, performing all the normal components of grooming behavior. This excessive grooming is only seen after the head sting and cannot be attributed to stress, to contamination of the body surface or to systemic or peripheral effects. This suggests that the venom is activating a neural network for grooming. We suggest that the venom induces prolonged grooming by stimulating dopamine receptors in the cockroach, for the following reasons. (1) Reserpine, which causes massive release of monoamines, induces excessive grooming. (2) Dopamine injected into the hemocoel also induces excessive grooming and is significantly more effective than octopamine or serotonin. In addition, the dopamine agonist SKF 82958 induces excessive grooming when injected directly into the subesophageal ganglion. (3) Injection of the dopamine antagonist flupenthixol greatly reduces venom-induced grooming. (4) Dopamine, or a dopamine-like substance, is present in the venom.

Journal Article↗
PubMed2002

A novel protein toxin from the deadly box jellyfish (Sea Wasp, Habu-kurage) Chiropsalmus quadrigatus.

The deadly box jellyfish (Sea Wasp, Habu-kurage in Japanese) Chiropsalmus quadrigatus Haeckel (Cubozoa) is distributed widely in the tropical Pacific region. In Japan, three fatal cases due to stings from this species have been reported officially. We successfully isolated C. quadrigatus toxin-A (CqTX-A, 44 kDa), a major proteinaceous toxin, for the first time, from the nematocysts of C. quadrigatus. CqTX-A showed lethal toxicity to crayfish when administered via intraperitoneal injection (LD50 = 80 microg/kg) and hemolytic activity toward 0.8% sheep red blood cells (ED50 = 160 ng/ml). Furthermore, we sequenced the cDNA encoding CqTX-A. The deduced amino acid sequence of CqTX-A (462 amino acids) showed 25.2% and 21.6% sequence similarity to Carybdea rastoni toxins (CrTXs) and Carybdea alata toxin-A (CrTX-A), respectively, which are Cubozoan jellyfish toxins.

Amino Acid Sequence↗
PubMed2004

['Vegetable wasps and plant worms' and G-protein-coupled receptors].

Following the discovery of an immunosuppressive substance isolated from one of the entomopathogenic fungi 'vegetable wasps and plant worms', FTY720, whose immunosuppressive action is more potent than that of cyclosporin, was developed. In contrast to classical immunosuppressants such as cyclosporin, FTY720 does not affect the growth, maturation and activation of lymphocytes, but causes a reduction in the number of circulating lymphocytes as a result of enhanced homing of lymphocytes to the secondary lymphoid organs. It has recently been reported that FTY720 is phosphorylated in vivo by sphingosine kinase, and the phosphorylated FTY720 is a ligand of the receptors of sphingosine 1-phosphate (S1P), which are G-protein-coupled receptors. S1P has been recognized most prominently as a platelet-derived lipid mediator which regulates several functions of endothelial and smooth muscle cells. In addition, recent studies have suggested the crucial roles for S1P in immunological, and inflammatory modulation.

Cordyceps↗
PubMed2001

Silver staining of nucleolar organizer regions (NOR) in some species of Hymenoptera (bees and parasitic wasp) and Coleoptera (lady-beetle).

Adaptations of the nucleolar organizer regions (NOR) banding technique using precipitation of silver salts significantly improved the NOR characterization of some species of hymenopterans and one coleopteran. The bee Melipona marginata (2n = 18) showed one metacentric pair of chromosomes with a NOR in the pericentromeric position. The parasitic wasp Mellitobia australica (2n = 12) also showed one metacentric pair with a strongly Ag-positive NOR. The male lady-beetle Cycloneda sanguinea (2n = 18 + Xy(p)) displayed a NOR on a pair of acrocentric autosomes. In the male Euglossa sp. (a haplodiploid species) (n = 21) the NOR were multiple, and occurred in five chromosomes. In the bee Plebeia sp. 1 (2n = 34) the NOR seemed restricted to one of the homologues of a metacentric pair. The systematic advances brought out by using this technique in the context of current theories of karyotypic evolution of these taxa are described and discussed.

Animals↗
PubMed2001

Structure of ovarioles in adult queens and workers of the common wasp, Vespula germanica (Hymenoptera: Vespidae).

The ovaries of the common wasp, Vespula germanica are polytrophic-meroistic and consist of 2-3 (workers) or 7 (queens) ovarioles. The ovarioles are differentiated into three regions: a terminal filament, a germarium, and a vitellarium. The germaria of both castes consist of two zones: an anterior zone of germ-cell cluster formation and a posterior one of germ-cell cluster differentiation. The vitellaria comprise 4-6 (workers) or 7-10 (queens) ovarian follicles (egg chambers). Each chamber consists of an oocyte and about 60 isodiametric nurse cells (trophocytes). The egg chambers have been arbitrarily classified into four developmental categories: early and late previtellogenic, vitellogenic, and choriogenic. The process of oogenesis in workers proceeds only up to the onset of the late previtellogenesis. Neither vitellogenic nor choriogenic egg chambers were observed in this caste. During early and late previtellogenesis the envelope of the oocyte nucleus proliferates and becomes highly folded. This process leads to the formation of characteristic organelles, termed accessory nuclei (AN). Although AN arise in the oocytes of both queens and workers, their number in the latter caste is always considerably lower. At the onset of the late previtellogenesis AN start to migrate towards the periphery of the oocyte where they reside till the end of oogenesis. The physiological state of the worker ovaries is discussed in the light of the presented results.

Animals↗
PubMed2003

[Up to allergy specialists' consideration: did Pharaoh Menes die of a wasp sting?].

Several allergologists interested in allergies to wasp venom, pass a seemingly probable information that the first Egyptian pharaoh, Menes, was allergic to the venom of stinging insects, and died of an insect sting while on a long journey, somewhere in the area of present-day Great Britain. A relief decorating the pharaoh's sarcophagus and the tomb's walls is to prove the historicity of this event. The whole story is a typical hoax. Insufficient historical sources do not confirm the thesis that Menes visited Europe. The tomb which is considered to be his burial site, contained no sarcophagus, reliefs or paintings. The above-mentioned relief is a contemporary illustration which should raise suspicions even of a layman who looked at it carefully. It is interesting why so many respectable scientists believe the hoax and quote it without previous verification.

Animals↗
PubMedDate not supplied

Myasthenia gravis and acute respiratory muscle paralysis following wasp sting.

A 34-year-old lady presented with generalised weakness of body, indistinguishable from myasthenia gravis within 24 hours of a wasp sting. Respiratory muscle paralysis leading to respiratory failure developed and mechanical ventilatory support was required. The patient made an uneventful recovery.

Acute Disease↗
PubMed1987

Block of synaptic transmission in insect CNS by toxins from the venom of the wasp Megascolia flavifrons (Fab.).

1. The effects of the venom and its fractions of Megascolia flavifrons have been studied on synaptic transmission and axonal excitability of the giant interneuron of the cockroach. 2. The venom does not affect axonal excitability, but blocks synaptic transmission, and induces postsynaptic depolarization with a delay. 3. Five different active fractions have been recognized. 4. Three fractions of them contain substances already identified as histamine, Thr6 bradykinin and Thr6 bradykinin-Lys-Ala (megascoliakinin). 5. Three fractions contain activities, which have not yet been chemically identified. 6. All of them, and also bradykinin block synaptic transmission; histamine was not active.

Animals↗