Histological and ultrastructural studies of Beauveria bassiana infection in Leptinotarsa decemlineta larvae during ecdysis

Studies of Leptinotarsa decemlineata larvae infected by Beauveria bassiana during ecdysis have enabled us to define the modes of fungal penetration employed to enter the ecdysial cuticle. We have observed the mechanically active passage of the penetrant hyphae and have followed the growth of the filaments and blastospore formation in the molting fluid. The attack of the new integument and its consequent alteration and the entry into the body cavity have also been studied. The infection develops rapidly in some of the larvae which die in premolt, while others are able to molt. Conditions rendered abnormal due to the presence of the fungus cause integumentary injuries which serve as an important factor in pathogenesis since they enhance the entry of fungal elements and bacteria thereby inducing septicemia. Contaminated larvae are able to molt, showing no signs of injury or disease, and survive for a long time, until the fungus finally invades the organism and causes death. This postponement of mortality shows that molting and hemocytic reactions are, to a certain extent, an effective defense mechanism. These last observations can be useful in the understanding of pathological processes associated with a hidden phase of fungal infection.     

Construction of a colony bank of E. coli containing hybrid plasmids representative of the Bacillus subtilis 168 genome. Expression of functions harbored by the recombinant plasmids in B. subtilis.

Summary A collection of about 2500 clones containing hybrid plasmids representative of nearly the entire genome of B. subtilis 168 was established in E. coli SK1592 by using the poly(dA)·poly(dT) joining method with randomly sheared DNA fragments and plasmid pHV33, a bifunctional vector which can replicate in both E. coli and B. subtilis. Detection of cloned recombinant DNA molecules was based on the insertional inactivation of the Tc gene occurring at the unique BamHI cleavage site present in the vector plasmid.Thirty individual clones of the collection were shown to hybridize specifically with a B. subtilis rRNA probe. CCC-recombinant plasmids extracted from E. coli were pooled in lots of 100 and used to transform auxotrophic mutants of B. subtilis 168. Complementation of these auxotrophic mutations was observed for several markers such as thr, leuA, hisA, glyB and purB. In several cases, markers carried by the recombinant plasmids were lost from the plasmid and integrated into the chromosomal DNA. Loss of genetic markers from the hybrid plasmids did not occur when a rec ^- recipient strain of B. subtilis was used.Abbreviations Ap^R resistance to ampicillin - Tc^R resistance to tetracycline - Cm^R resistance to chloramphenicol - CCC covalently closed circular duplex - Mdal magadalton     

Lagomorph-constant region IgG allotypes: Shared e determinants inOchotona sp

The search for C allotypes as defined by the markers common to domestic rabbits (Oryctolagus) was extended to additional lagomorphs of the familiesLeporidae andOchotonidae. None of theOchotona sera obtained from Afghanistan and Iran (Ochotona rufescens) exhibited the d11, d12, or e14 allotypes. The e15 marker was detected only by radioimmune binding assays. Comparative inhibition of binding assays revealed similarities with other lagomorphs with respect to the e15i determinant. As in some variants of hare e15 markers, the e15j determinant is absent inOchotona. The results provided a revised phylogenetic scheme for the evolution of the C gene on the basis of the e-series allotypes.     

Effects of methylazoxymethanol given at different stages of postnatal life on development of the rat brain. Comparison with those of thyroid deficiency

Newborn rats were treated at different stages of their development with low doses of methylazoxymethanol acetate. The postnatal increase of the DNA content of the cerebrum did not differ from that of controls. In the cerebellum, the DNA content was transitorily reduced, but later, the external granular layer became thicker and DNA deposition increased in comparison with controls; finally, the cerebellar DNA returned to a normal value. Morphological abnormalities of the cerebellum, abnormal orientation of migrating cells, scattering of Purkinje cell bodies within the internal granule cells and specially striking abnormalities of the morphology and orientation of Purkinje cell dendrites were noted in rats treated with MAM from birth to day 3. The effects on the Purkinje cell morphogenesis persisted but were much less marked when MAM was given from 4 to 7 or from 8 to 11 days. Neonatal thyroid deficiency, as MAM-treatment between days 0 and 3, leads to an abnormal position of Purkinje cell bodies within the cerebellar cortex; it also leads to morphological abnormalities of their dendritic arborization which closely resemble those observed after MAM-treatment during the second postnatal week. It also alters the cell formation in the cerebellum. Thyroid deficiency probably exerts its effect on cell formation earlier than previous biochemical studies have shown. On another hand, the morphological abnormalities of Purkinje cell arborizations in the thyroid-deficient animals may be partly due to the perturbations of cell formation which persist later in the cerebellum.     

v-myb Transformation of Xeroderma pigmentosum human fibroblasts: Overexpression of the c-Ha-ras oncogene in the transformed cells

Human Xeroderma pigmentosum “normal” fibroblasts AS16 (XP4 VI) were transformed after transfection with a recombinant v-myb clone. In this clone (pKXA 3457) derived from avian myeloblastosis virus (AMV), the expression of the oncogene sequences is driven by the AMV U-5 LTR promoter. The transformed cells (ASKXA), which have integrated a rearranged v-myb oncogene, grow in agar, are not tumorigenic in nude mice, and express a 45-kDa v-myb protein. The HMW DNA of these cells transform chicken embryo fibroblasts. The c-Ha-ras oncogene is overexpressed in the ASKXA cells but not in the parental “normal” AS16 cells and a revertant clone (ASKXA Cl 1.1 G). Our results lead to the conclusion that the XP fibroblasts are phenotipically transformed by the presence of the transfected v-myb oncogene, which is able to induce an overexpression of the c-Ha-ras gene.     

Anatomy and ultrastructure of the proboscis in Mesorhynchus terminostylis (Platyhelminthes,Rhabdocoela)

The ultrastructural organization of the proboscis in Mesorhynchus terminostylis is distinctly different from that in other members of the Polycystididae in which it is currently classified. The sheath epithelium is formed by three belts, all with intra-epithelial nuclei. The apical belt of the bipartite cone epithelium has a single intrabulbar nucleus, and the basal belt possesses five insunk nucleiferous cell parts behind the bulb. Six types of glands surface through the epithelia; the three types emerging through the cone epithelium can be homologized with those described for Polycistis naegelii. Only uniciliary receptors are found in the epithelium. The musculature in the bulb has a very loose appearance, and the bulbar septum appears to be a bipartite basement membrane. The septum can be considered the basement membrane of the cone epithelium as if the contractile portion of the inner longitudinal muscles have invaded the epithelium and come to lie between the epithelial cells and the basement membrane. Thus the inner musculature of the bulb is entirely intraepithelial as is the case for Psammorhynchus tubulipenis and Cytocystis clitellatus. The systematic position of M. terminostylisremains uncertain but seems to lie between Psammorhynchus and Cytocystis on one hand and Koinocystididae and Polycystididae on the other.     

DNA sequence analysis of the lamB gene from Klebsiella pneumoniae: implications for the topology and the pore functions in maltoporin.

Summary We have determined the sequence of the lamB gene from Klebsiella pneumoniae. It encodes the precursor to the LamB protein, a 429 amino acid polypeptide with maltoporin function. Comparison with the Escherichia coli LamB protein reveals a high degree of homology, with 325 residues strictly identical. The N-terminal third of the protein is the most conserved part of the molecule (1 change in the signal sequence, and 13 changes up to residue 146 of the mature protein). Differences between the two mature proteins are clustered mainly in six regions comprising residues 145–167, 173–187, 197–226, 237–300, 311–329, and 367–387 (K. pneumoniae LamB sequence). The most important changes were found in regions predicted by the two-dimensional model of LamB folding to form loops on the cell surface. In vivo maltose and maltodextrin transport properties of E. coli K 12 and K. pneumoniae strains were identical. However, none of the E. coli K12 LamB-specific phages was able to plaque onto K. pneumoniae. Native K. pneumoniae LamB protein forms highly stable trimers. The protein could be purified by affinity chromatography on starch-Sepharose as efficiently as the E. coli K12 LamB protein, indicating a conservation of the binding site for dextrins. However, none of the monoclonal antibodies directed against native E. coli K12 LamB protein recognized native purified K. pneumoniae LamB protein. These data indicate that most of the variability occurs within exposed regions of the protein and provide additional support for the proposed model of LamB folding. The fact that the N-terminal third of the protein is highly conserved is in agreement with the idea that it is part of, or constitutes, the pore domain located within the transmembranous channel and that it is not accessible from the cell surface.     

Hormonal effects of zinc on growth in children

Zinc deficiency impairs the metabolism of thyroid hormones, androgens, and above all growth hormones. In view of their important role in growth, it is not surprising to find growth disorders associated with zinc deficiency. Stunted growth linked to zinc deficiency is found during gestation, and also in the newborn and children up to adolescence. Depending on the country, 5–30% of children suffer from moderate zinc deficiency, responsible for small-for-age height. Zinc supplementation has proven effective in many studies, mainly in children where zinc deficiency has first been found. Finally, zinc supplementation makes it possible in certain cases to overcome resistance to growth hormone treatment.     

Stimulation of shoot regeneration from cotyledons of Helianthus annuus by the ethylene inhibitors,silver and cobalt

The effects of CoCl₂, AgNO₃ and ethylene released by exogenous 2-chloroethylphosphonic acid (Ethephon), were studied on shoot regeneration from cotyledons of Helianthus annuus cv. E8206R, a poorly regenerative cultivar. Inhibition of ethylene biosynthesis by CoCl₂, at concentrations of 20 K, provoked a substantial enhancement of shoot regeneration (30 %): the control was poorly regenerative. However, CoCl₂ had no effect when Ethephon was supplied. Inhibition of ethylene action by AgNO₃, at concentrations of 10–25 M, caused a significant increase in plant regeneration: 25 % instead of 1.2 % in the control. Furthermore, addition of Ethephon to AgNO₃-treated tissues failed to reduce the stimulation of shoot regeneration caused by AgNO₃. On the basis of these findings, it is suggested that ethylene inhibits the regeneration process from cotyledons of sunflower.Abbreviations NAA 1-naphthalene acetic acid - BAP 6-benzylamino-purine - GA₃ gibberellic acid - Ethephon 2-chloroethylphosphonic acid - MS Murashige and Skoog medium - AVG aminoethoxyvinylglycine     

IF-3 crosslinking to Escherichia coli ribosomal 30 S subunits by three different light-dependent procedures: Identification of 30 S proteins crosslinked to IF-3—Utilization of a new two-stage crosslinking reagent, p-nitrobenzylmaleimide

We here report the results of using three light-dependent procedures for crosslinking IF-3 to 30 S proteins within an IF-3·30 S complex. In the first procedure, employing FMN as a photosensitizer, protein S12 is found to be the only major crosslinked protein. In the second procedure, IF-3 is first reacted with the new two-stage crosslinking reagent, p-nitrobenzylmaleimide (PNBM), and the PNBM—IF-3·30 S complex is irradiated. The major crosslinked proteins are S3 > S2, S12, S18. Small amounts of crosslinked S11 and S21 are also found. In the third procedure, the IF-3·30 S complex is reacted with PNBM and then irradiated. The major crosslinked proteins are S12 > S3 > S11 and small amounts of crosslinked S1, S13, and S21 are also found. These results are compared with results obtained by others using different crosslinking procedures and are used to discuss the Lake and Kahan model (J. A. Lake and L. Kahan, 1975, J. Mol. Biol., 99, 631–644, and J. A. Lake, 1978, in Advanced Techniques in Biological Electron Microscopy II, Koehler, J. K., ed., pp. 173–211, Springer-Verlag, Berlin) for IF-3 binding to 30 S subunits.