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Biomedical subjects

H Charles

Publications and source records attributed to H Charles.

At least 19 recordsLinked to original sources
PubMed1999

Four intracellular genomes direct weevil biology: nuclear, mitochondrial, principal endosymbiont, and Wolbachia.

Cell physiology in the weevil Sitophilus oryzae is coordinated by three integrated genomes: nuclear, mitochondrial, and the "S. oryzae principal endosymbiont" (SOPE). SOPE, a cytoplasmic bacterium (2 x 10(3) bacteria per specialized bacteriocyte cell and 3 x 10(6) bacteria per weevil) that belongs to the proteobacteria gamma3-subgroup, is present in all weevils studied. We discovered a fourth prokaryotic genome in somatic and germ tissues of 57% of weevil strains of three species, S. oryzae, Sitophilus zeamais, and Sitophilus granarius, distributed worldwide. We assigned this Gram-negative prokaryote to the Wolbachia group (alpha-proteobacteria), on the basis of 16S rDNA sequence and fluorescence in situ DNA-RNA hybridization (FISH). Both bacteria, SOPE and Wolbachia, were selectively eliminated by combined heat and antibiotic treatments. Study of bacteria involvement in this insect's genetics and physiology revealed that SOPE, which induces the specific differentiation of the bacteriocytes, increases mitochondrial oxidative phosphorylation through the supply of pantothenic acid and riboflavin. Elimination of this gamma3-proteobacterium impairs many physiological traits. By contrast, neither the presence nor the absence of Wolbachia significantly affects the weevil's physiology. Wolbachia, disseminated throughout the body cells, is in particularly high density in the germ cells, where it causes nucleocytoplasmic incompatibility. The coexistence of two distinct types of intracellular proteobacteria at different levels of symbiont integration in insects illustrates the genetic complexity of animal tissue. Furthermore, evolutionary timing can be inferred: first nucleocytoplasm, then mitochondria, then SOPE, and finally Wolbachia. Symbiogenesis, the genetic integration of long-term associated members of different species, in the weevil appears to be a mechanism of speciation (with Wolbachia) and provides a means for animals to acquire new genes that permit better adaptation to the environment (with SOPE).

Biological Evolution↗
PubMed1999

Physical and genetic map of the genome of Buchnera, the primary endosymbiont of the pea aphid Acyrthosiphon pisum.

The genome of Buchnera, an endosymbiotic bacterium of the pea aphid Acyrthosiphon pisum, was characterized by pulse-field gel electrophoresis (PFGE) as a circular DNA molecule of 657 kb. The enzymes I-CeuI, CpoI, ApaI, SmaI, NaeI, SacII, MluI, FspI, and NruI were used to cleave the DNA of Buchnera into fragments of suitable size for PFGE analysis. A physical map of the Buchnera genome, including restriction fragments from seven of these enzymes, was constructed using double cutting, partial digestion, and hybridization with linking fragments, and 29 genes and operons were localized on the map. In addition, the genomic map of Buchnera was compared with those of Escherichia coli and Haemophilus influenzae. The gene order in Buchnera is more similar to that of E. coli than to H. influenzae. The dramatic shrinkage of the Buchnera genome compared with those of other members of the closely related Enterobacteriaceae family is discussed in terms of evolution under the influence of the intracellular symbiotic association.

Animals↗
PubMed1998

Molecular characterization of the principal symbiotic bacteria of the weevil Sitophilus oryzae: a peculiar G + C content of an endocytobiotic DNA.

The principal intracellular symbiotic bacteria of the cereal weevil Sitophilus oryzae were characterized using the sequence of the 16S rDNA gene (rrs gene) and G + C content analysis. Polymerase chain reaction amplification with universal eubacterial primers of the rrs gene showed a single expected sequence of 1,501 bp. Comparison of this sequence with the available database sequences placed the intracellular bacteria of S. oryzae as members of the Enterobacteriaceae family, closely related to the free-living bacteria, Erwinia herbicola and Escherichia coli, and the endocytobiotic bacteria of the tsetse fly and aphids. Moreover, by high-performance liquid chromatography, we measured the genomic G + C content of the S. oryzae principal endocytobiotes (SOPE) as 54%, while the known genomic G + C content of most intracellular bacteria is about 39.5%. Furthermore, based on the third codon position G + C content and the rrs gene G + C content, we demonstrated that most intracellular bacteria except SOPE are A + T biased irrespective of their phylogenetic position. Finally, using the hsp60 gene sequence, the codon usage of SOPE was compared with that of two phylogenetically closely related bacteria: E. coli, a free-living bacterium, and Buchnera aphidicola, the intracellular symbiotic bacteria of aphids. Taken together, these results show a peculiar and distinctly different DNA composition of SOPE with respect to the other obligate intracellular bacteria, and, combined with biological and biochemical data, they elucidate the evolution of symbiosis in S. oryzae.

Animals↗
PubMed1997

A molecular aspect of symbiotic interactions between the weevil Sitophilus oryzae and its endosymbiotic bacteria: over-expression of a chaperonin.

Specific proteins of symbiosis were analyzed by the comparison of two-dimensional electrophoresis protein patterns of symbiotic and aposymbiotic strains of the weevil Sitophilus oryzae. One protein was shown to be exclusively expressed in the aposymbiotic strain and three proteins, including a chaperonin, were characterized in the symbiotic strain pattern. The groE-like operon, encoding the two chaperonins groES and GroEL-like proteins of the endocytobiotes, was sequenced. It was found to be very similar to the groE operon of Escherichia coli (82% identity). In vitro and ex vivo experiments of protein labelling demonstrated that almost 40% of the endocytobiote protein synthesis ex vivo is focused on the GroEL-like protein. Finally, we showed by northern blotting that heat shock at 38 degrees C results in groEL mRNA accumulation inside the endocytobiotes. This work supports the hypothesis that chaperonins could have an essential physiological function in the maintenance of the symbiotic association.

Amino Acid Sequence↗
PubMed1996

Developing a leg ulcer management programme.

Compression therapy is an essential component in the treatment of venous leg ulcers. Comprehensive education and training and support of district nurses in leg ulcer management is essential.

Bandages↗
PubMed1995

The impact of leg ulcers on patients' quality of life.

The pain of leg ulceration can dominate patients' lives and can have serious psychological and social effects on patients' quality of life. A phenomenological approach was used in this study to obtain rich data on patients' experiences. A feeling of loss of control and lack of faith in the professionals treating the condition was found.

Adult↗
PubMed1995

Presence of a protein specific of endocytobiosis (symbionin) in the weevil Sitophilus.

Chaperonins are ubiquitous proteins found in all prokaryotic and eukaryotic cells. They are overproduced in several parasitic bacteria and are implicated in at least 2 types of endocytobiosis: in amoebae and in aphids. This work puts in evidence that a protein named symbionin, which shows an immunological homology with the E. coli protein GroEL, is present in the symbiotic relationship of 3 species of Sitophilus (S. oryzae, S. granarius, and S. zeamais). This protein is neither found in the naturally asymbiotic specie S. linearis nor in the aposymbiotic strain of S. oryzae obtained in the laboratory. This symbionin is stored in a great quantity within endocytobiotes and its amino acid composition seems to corroborate its chaperonin resemblance rather than its possible function as one of the insect storage proteins already described in the literature.

Animals↗
PubMed1991

Probing the role of cysteine residues in the CheR methyltransferase.

The CheR methyltransferase catalyzes the transfer of methyl groups from S-adenosylmethionine to specific glutamyl residues in bacterial chemoreceptor proteins. Studies with sulfhydryl reagents such as p-chloromercuribenzoate, N-ethylmaleimide, and 5,5'-dithiobis(2-nitrobenzoate) suggest that a cysteine residue is required for enzyme activity. The nucleotide sequence of the cheR gene predicts a 288-amino acid protein with cysteine residues at positions 31 and 229. To ascertain the role of these cysteine residues in the structure and function of the enzyme, oligonucleotide-directed mutagenesis was used to change each cysteine to serine. Whereas the Cys229-Ser mutation had essentially no effect on transferase activity, the Cys31-Ser mutation caused an 80% decrease in enzyme activity. The double mutant in which both cysteines were replaced by serines also had markedly reduced transferase activity. Preincubation of the wild type or Cys229-Ser proteins with either S-adenosylmethionine or beta-mercaptoethanol protected it from inhibition by sulfhydryl reagents, whereas prior incubation with the second substrate, the Tar receptor, gave partial protection. From these studies, Cys31 appears to be necessary for enzyme activity, and it seems to be located in the vicinity of the active site.

Base Sequence↗
PubMed1988

Internal eye wall resection in the management of uveal melanoma.

Twenty patients with presumed uveal melanoma underwent internal eye wall resection. It was the primary procedure in 13 patients who had tumours within 2 disc diameters of the optic nerve head and was combined with external resection in the remainder. Malignant melanoma was confirmed histologically in 15 patients; the diagnosis was a benign tumour in the other 5. The length of follow-up ranged from 2 to 37 (mean 19) months. In all cases the retina was completely attached at the time of last examination. The visual acuity ranged from 20/40 to hand movements; nine patients had an acuity of 20/400 or better. At the time of writing no metastatic disease or local recurrence had developed in any of the 15 patients in whom malignant melanoma was diagnosed.

Adolescent↗
PubMed1987

External drainage of subretinal fluid with a contact Nd:YAG laser.

We used a Nd:YAg laser fit with a fiberoptic cord and sapphire tip to drain subretinal fluid externally in patients with rhegmatogenous retinal detachment. The direct contact between the laser and the choroid allowed for controlled cutting and coagulation of the intervening choroidal vasculature. The drainage was successfully achieved with no complication.

Drainage↗
PubMed1987

Management of an extruded footplate of an anterior chamber lens with the Nd:YAG laser.

A footplate of an anterior chamber lens that extruded through clear cornea was treated by severing the protruding haptic with the Nd:YAG laser and removing it surgically. During the procedure, the remainder of the implant was repositioned and vitreous traction was relieved by pars plana vitrectomy. This technique appeared less injurious to the eye than attempting to cut all four fibrosed haptics and remove the entire implant.

Aged↗
PubMed1981

Granulomatous optic neuropathy.

A 24-year-old woman was seen with painless, progressive, unilateral visual acuity loss, optic nerve swelling, and opticociliary shunt vessels. Results of a skull series and conventional tomography showed enlargement and erosion of the optic canal. In addition, computed tomography (CT) disclosed a thickened optic nerve consistent with optic nerve sheath meningioma. A preoperative diagnosis of granulomatous optic neuropathy was based on the presence of mild posterior uveitis, "snowball" opacities in the vitreous ("string of pearl" sign), and a slightly elevated angiotensin-converting enzyme level. A specimen from a biopsy by means of a craniotomy indicated granulomatous optic nerve involvement with chiasmal invasion. The systemic effects of steroids for six months resulted in a modest improvement of visual acuity and restoration of normal optic nerve structure on repeated CT.

Adult↗