Molecular attempt to identify prey organisms of lobster phyllosoma larvae

ABSTRACT:   A molecular approach was adopted to investigate the natural diets of palinurid and scyllarid lobster phyllosoma larvae. The central domain of the 18S rDNA gene was amplified using nested polymerase chain reaction (PCR) and genomic DNA extracted from the larval hepatopancreas. The resulting 18S rDNA clones were screened using restriction fragment length polymorphism (RFLP) analysis, and then FASTA homology search and phylogenetic analysis were performed on the nucleotide sequences to identify the source of the eukaryotic organisms. The feasibility of this method was confirmed using the laboratory-reared phyllosoma larvae of the Japanese spiny lobster Panulirus japonicus that were fed either with common mussel Mytilus edulis gonads or with Artemia nauplii exclusively. Among the 804 clones isolated from five wild-caught mid- to late-stage phyllosoma larvae (three palinurids and two scyllarids), 0–132 clones per sample possessed restriction profiles distinct from those of the hosts. The Cnidaria and Urochordata DNA were identified from both the palinurid and the scyllarid larvae, which were thought to be prey animals for the mid- to late-stage phyllosoma larvae.     

Isolated chloroplast division machinery can actively constrict after stretching

Chloroplast division involves plastid-dividing, dynamin, and FtsZ (PDF) rings. We isolated intact supertwisted (or spiral) and circular PDF machineries from chloroplasts of the red alga Cyanidioschyzon merolae. After individual intact PDF machineries were stretched to four times their original lengths with optical tweezers, they spontaneously returned to their original sizes. Dynamin-released PDF machineries did not retain the spiral structure and could not be stretched. Thus, dynamin may generate the motive force for contraction by filament sliding in dividing chloroplasts, in addition to pinching-off the membranes.     

Spontaneous vacuolar degeneration of the thyroid follicular epithelium in cynomolgus monkeys

Vacuolar degeneration of the thyroid follicular epithelium was observed in two untreated female cynomolgus monkeys assigned to control groups. In light microscopy, large vacuoles containing a homogenous substance occupied the basal region of the epithelium, and the nuclei had shifted toward the apical region. The vacuoles showed negative reactions to PAS and thyroglobulin. Electron microscopic observation revealed dilatation of the rough endoplasmic reticulum corresponding to the vacuoles. The plasma TSH, T3 and T4 levels determined for the samples kept frozen were within the normal ranges, suggesting that the thyroid function was kept intact.     

Some Measurement Results on Sulfate Aerosol Concentration in and above a Pine Canopy

Profile of sulfate aerosol (SO₄ ^2?) concentration was measured for four days at six heights in and above a 15m-high canopy of pine plantation during 6th and 10th August. 1999. The concentration was the lowest (about 2 nmol/m³) on 6th, and gradually increased to 9th showing the maximum values of about 13 nmol/m³, and then decreased to 2 nmol/m³ on 10th. The vertical profiles of SO₄ ^2? concentration showed mostly higher in the canopy than above the canopy. As for the vertical profiles above the canopy on 8th and 10th, the minimum was observed just above the canopy (16m), showing SO₄ ^2? transport from the upper air layer to the canopy. While on 9th the profiles that are higher concentration just above the canopy and lower at the upper air layer were observed, suggesting SO₄ ^2? emission from the canopy to the upper air layer.     

Mechanism of resistance to carpropamid in Magnaporthe grisea

The inhibitory activity of carpropamid on scytalone dehydratase (SDH) extracted from a carpropamid-resistant strain of Magnaporthe grisea (Hebert) Barr was dramatically reduced in comparison with that on SDH extracted from the sensitive strain. A single-point mutation (G to A) located at the upstream region (233 bp downstream from the ATG codon) resulting in a one-amino-acid substitution (valine [GTG] 75 to methionine [ATG]: V75M) was found in the resistant strain. To examine whether the V75M mutation is the primary reason for decreasing the sensitivity of SDH to carpropamid, the SDH cDNAs of both the sensitive and the resistant strain were cloned into a GST-fused protein expression vector-system. The recombinant SDHs of both strains exhibited the same sensitivities to carpropamid as those extracted from the mycelia of the respective strains. These data clearly revealed that the V75M mutation causes the low sensitivities of the SDHs of the carpropamid-resistant strains, and strongly suggests that the V75M mutation confers resistance of these strains to carpropamid.     

Production and characterization of monoclonal antibodies against midgut of ixodid tick,Haemaphysalis longicornis

There are concerted efforts toward development of tick vaccines to replace current chemical control strategies that have serious limitations [Parasitologia 32 (1990) 145; Infectious Disease Clinics of North America (1999) 209-226]. In this study, monoclonal antibodies (mAbs) specific to Haemaphysalis longicornis midgut proteins were produced and characterized. Eight antibody-secreting hybridomas were cloned and the mAbs typed as IgG1, IgG2a and IgG2b. On immunoblots, all mAbs reacted with a midgut protein band of about 76 kDa. All mAbs uniformly immunogold-stained the surface or epithelial layers of H. longicornis midgut and endosomes. Adult ticks (50%) that fed on an ascitic mouse producing the IgGs developed a red coloration and did not oviposit. As such, the 76 kDa protein that reacted with the mAbs could, therefore, be a potential candidate for tick vaccine development.     

Passive immunization with monoclonal antibodies: effects on Haemaphysalis longicornis tick infestation of BALB/c mice

Tick vaccine development plays an important role in current tick control strategies. Previously, we have produced three different isotypes of monoclonal antibodies (mAbs) which recognized a midgut protein of adult Haemaphysalis longicornis. These mAbs, typed as IgG1, 2a, and 2b, reacted with a 76 kDa surface protein of midgut cells. We speculated that the 76 kDa protein may be an unknown antigen for a tick vaccine and the three mAbs may work as probes to clone the protein. In this study, to test whether these three isotypes have anti-tick effects and if so which works more effectively, we conducted passive immunization in BALB/c mice with each of the mAbs, and infested the mice with adult ticks. All isotypes significantly reduced the number of hatched larvae, compared to controls, however, no differences in the magnitude of the reduction were observed among the three.