Detection of hybrid formation between peptide nucleic acids and DNA by fluorescence polarization in the presence of polylysine

A new method for the detection of PNA/DNA hybrids is presented. In this method, short PNA probes (9-13 mer) are labeled with a fluorescent dye and allowed to hybridize to target DNA molecules. A cationic polyamino acid, such as polylysine, is then added to the reaction mixture, whereupon the DNA molecules bind electrostatically to this polycation. The PNA probes, which are uncharged or may carry only a small charge due to the fluorescent dye, do not bind to polylysine unless hybridized to the negatively charged DNA target. The binding of the labeled PNA/DNA hybrid to the high-molecular-weight polymer leads to a significant change in the rotational correlation time of the fluorophore attached to the PNA. This can be conveniently detected by measuring the fluorescence polarization of the latter. The method is completely homogeneous because no separation of free from bound PNA probe is required. The hybridization and dehybridization reactions can be followed in real time. The method has been applied to the typing of single-nucleotide polymorphisms in PCR products.

The Arabidopsis CLAVATA2 gene encodes a receptor-like protein required for the stability of the CLAVATA1 receptor-like kinase

The CLAVATA2 (CLV2) gene regulates both meristem and organ development in Arabidopsis. We isolated the CLV2 gene and found that it encodes a receptor-like protein (RLP), with a presumed extracellular domain composed of leucine-rich repeats similar to those found in plant and animal receptors, but with a very short predicted cytoplasmic tail. RLPs lacking cytoplasmic signaling domains have not been previously shown to regulate development in plants. Our prior work has demonstrated that the CLV1 receptor-like kinase (RLK) is present as a disulfide-linked multimer in vivo. We report that CLV2 is required for the normal accumulation of CLV1 protein and its assembly into protein complexes, indicating that CLV2 may form a heterodimer with CLV1 to transduce extracellular signals. Sequence analysis suggests that the charged residue in the predicted transmembrane domain of CLV2 may be a common feature of plant RLPs and RLKs. In addition, the chromosomal region in which CLV2 is located contains an extremely high rate of polymorphism, with 50 nucleotide and 15 amino acid differences between Landsberg erecta and Columbia ecotypes within the CLV2 coding sequence.

The Arabidopsis CLAVATA2 gene encodes a receptor-like protein required for the stability of the CLAVATA1 receptor-like kinase

The CLAVATA2 (CLV2) gene regulates both meristem and organ development in Arabidopsis. We isolated the CLV2 gene and found that it encodes a receptor-like protein (RLP), with a presumed extracellular domain composed of leucine-rich repeats similar to those found in plant and animal receptors, but with a very short predicted cytoplasmic tail. RLPs lacking cytoplasmic signaling domains have not been previously shown to regulate development in plants. Our prior work has demonstrated that the CLV1 receptor-like kinase (RLK) is present as a disulfide-linked multimer in vivo. We report that CLV2 is required for the normal accumulation of CLV1 protein and its assembly into protein complexes, indicating that CLV2 may form a heterodimer with CLV1 to transduce extracellular signals. Sequence analysis suggests that the charged residue in the predicted transmembrane domain of CLV2 may be a common feature of plant RLPs and RLKs. In addition, the chromosomal region in which CLV2 is located contains an extremely high rate of polymorphism, with 50 nucleotide and 15 amino acid differences between Landsberg erecta and Columbia ecotypes within the CLV2 coding sequence.

A microchip-based enzyme assay for protein kinase A

A microchip-based enzyme assay for protein kinase A is described. The microchips were prepared by standard photolithographic techniques. The assay reagents were placed in wells on the microchips, and electroosmosis was used to transport aliquots of these reagents into the network of etched channels, where the enzymatic reaction takes place. Protein kinase A catalyzes the transfer of a phosphate group from ATP to the serine residue of the heptapeptide LeuArgArgAlaSerLeuGly (Kemptide). The outcome of the enzymatic reaction was assessed by performing an on-chip electrophoretic separation of the fluorescently labeled peptide substrate and product. All liquid-handling steps were performed by controlling the electroosmotically driven flow from reagent and buffer wells using electrical current. On-chip dilutions of the peptide substrate, ATP and H-89, a known protein kinase A inhibitor, were performed and the kinetic constants (K(m), K(i)) of these compounds were determined. This prototype assay demonstrates the usefulness of the microchips for performing enzymatic assays for which fluorogenic substrates cannot easily be designed.

High-level expression of human lactoferrin in milk of transgenic mice using genomic lactoferrin sequence

In our previous study, transgenic mice were generated that expressed human lactoferrin (hLF) in milk using cDNA under control of the 2 kb bovine beta-casein promoter. The expression level of the protein in milk of 7 mice ranged from 1 to 200 microg/ml; 1 to 34 microg/ml in 6 mice and 200 microg/ml in 1 mouse. With the aim of inducing higher expression of the protein, we constructed an expression cassette comprised of 10 kb of the bovine beta-casein gene promoter and the hLF genomic sequence in place of the cDNA. The hLF genomic sequence of about 27 kb, spanning 23 kb of the entire coding region and 4 kb of the 3'-flanking sequence, was placed downstream the bovine beta-casein promoter. In total, 8 transgenic mice were generated from 31 mice (transgenic rate of 25.8%) born from the embryos microinjected with the 40-kb hLF expression cassette. Mammary-specific expression of the transgene was addressed by performing Northern hybridization of the total RNAs from various tissues of transgenic mice. Immunoblot analysis showed that the recombinant protein expressed in milk has the same molecular weight as the native protein. The amount of the protein in milk of 5 mice ranged from 60 to 6,600 microg/ml when judged by ELISA analysis. Three mice expressed the protein at the level higher than 500 microg/ml. These data suggest that the genomic lactoferrin sequence represents a valuable element for the efficient expression of the protein in milk of transgenic animals.

Extensive destruction of the eyeball by invasion of basal cell carcinoma of the eyelid

BACKGROUND

Eyeball destruction caused by invasion of basal cell carcinoma of the eyelid.

CASE

A 100-year-old woman showed extensive eyeball destruction caused by the invasion of basal cell carcinoma of the eyelid. Complete ophthalmologic examinations, including computed tomographic (CT) scans of the orbit, were performed. The patient underwent incisional biopsy and bacteriological examination of the exudate from the lesion.

OBSERVATIONS

Orbital CT scan showed a mass in the extraconal space of the right orbit, with extension to the adjacent sinus cavity without brain involvement. The remnant of the eyeball was posteriorly displaced. Pseudomonas aeruginosa was identified by culture examination of the exudate. Histological study of the biopsy specimen showed basal cell carcinoma of the noduloulcerative type.

CONCLUSIONS

Basal cell carcinoma of the eyelid had caused severe periorbital and eyeball destruction.

The Asian upper eyelid: an anatomical study with comparison to the Caucasian eyelid

OBJECTIVE

To evaluate the differences between Asian and Caucasian upper eyelid anatomy through cadaver dissection, histopathological study, and magnetic resonance imaging.

MATERIALS AND METHODS

Upper eyelids of 9 Korean and 5 Caucasian cadavers were dissected, and then were studied microscopically with hematoxylin-eosin, Masson trichrome, and elastin stains. Four healthy young Korean men were studied by dynamic high-resolution magnetic resonance imaging with regard to demonstration of upper eyelid structure.

RESULTS

More subcutaneous and suborbicularis fat, with a pretarsal fat component, is present in Asian eyelids. The Asian double eyelids showed an amount of fat intermediate between Asian single eyelids and Caucasian eyelids. Asian single eyelids showed fusion of the orbital septum to the levator aponeurosis below the superior tarsal border, while fusion is above the superior tarsal border in Caucasians. The preaponeurotic fat pad descends anteriorly to the tarsal plate in the Asian single eyelid, but not in the Caucasian eyelid. A pretarsal fat pad is identified in the Asian single eyelids.

CONCLUSIONS

The causes of absent or lower crease in the Asian upper eyelid are as follows: (1) the orbital septum fuses to the levator aponeurosis at variable distances below the superior tarsal border; (2) preaponeurotic fat pad protrusion and a thick subcutaneous fat layer prevent levator fibers from extending toward the skin near the superior tarsal border; and (3) the primary insertion of the levator aponeurosis into the orbicularis muscle and into the upper eyelid skin occurs closer to the eyelid margin in Asians. Structural differences relating to increased fat in the Asian upper eyelid include the presence of a pretarsal fat pad and a moderate fat increase in the double Asian eyelid.

Incidence of hepatocellular carcinoma in transgenic mice expressing the hepatitis B virus X-protein

BACKGROUND/AIMS

Chronic infection with hepatitis B virus is a high-risk factor for hepatocellular carcinoma in humans. The HBV X-protein, a multi-functional viral regulator, has been suspected to play a positive role in hepatocarcinogenesis, as demonstrated by the high incidence of hepatocellular carcinoma in HBx-expressing transgenic mice, although it is still controversial. The aim of this study was to generate transgenic mice expressing the HBV X-gene under authentic promoter control and to test whether the gene products can cause hepatic tumors.

METHODS

Three transgenic mouse lines were generated by microinjecting the X-gene construct into hybrid (C57BL/6 x DBA) eggs. Gene expression was tested by protein and mRNA analyses. During an observation period of 18 months, mice were sacrificed and organs subjected to histologic examinations.

RESULTS

Grossly defined hepatocellular carcinomas reproducibly were observed in mice expressing the X-protein, which were investigated through six generations from the age of 11 to 18 months. Among 14 transgenic mice investigated from the age of 11 to 18 months, 12 were found to have hepatocellular carcinoma, grossly or microscopically. The lesion of the hepatocellular carcinoma disclosed a significant increase in the proliferating cell nuclear antigen in the nuclei.

CONCLUSION

The incidence of hepatocellular carcinoma (86%) in our HBV X transgenic mice may be highly significant, since, except for one case, HBV X-gene transgenic mice produced in other laboratories did not develop liver tumor or any other pathologic phenomena.

Isolation of developmentally regulated novel genes based on sequence identity and gene expression pattern

Based on the surmise that a variety of genes might play important roles in embryonic development and tissue differentiation, and that some of them are likely to be expressed in undifferentiated ES cells, we attempted to identify new genes from the ES cell cDNA library. The modified method of expressed sequence tags (ESTs) and the examination of the expression patterns in adult tissues and in vitro differentiated ES cells were utilized in this study. We have isolated and identified several novel cDNA clones with interesting developmental expression pattern. Among the 83 clones randomly chosen, 23 clones (27.7%) have no homology to any sequences in public databases. The rest contain limited or complete sequence homology to the previously reported mammalian genes or ESTs, yet some clones have not been previously identified in the mouse. To examine the expression profile of clones during development and differentiation, sets of slot blots were hybridized with developmental stage specific or tissue specific probes. Out of 40 novel clones tested (21 totally unknown clones and 19 unidentified clones in mouse), most of them were up- or down-regulated as differentiation proceeded, and some clones showed differentiation-stage specific expression profiles. Surprisingly, a majority of genes were also expressed in adult tissues, and some clones even revealed tissue specific expression. These results demonstrate that not only was the strategy we employed in this study quite efficient for screening novel genes, but that the information gained by such studies would also be a useful guide for further analysis of these genes. It also suggests the feasibility of this approach to explore the genomewide network of gene expression during complicated biological processes, such as embryonic development and tissue differentiation.

Structure of the human lactoferrin gene and its chromosomal localization

The complete gene encoding the human lactoferrin (hLf) was isolated from a cosmid library and its structure was characterized. A detailed restriction map and the complete exon-intron structure of the gene are presented. The transcript is assembled from 17 exons like the bovine (bLf) and murine lactoferrin (mLf) genes, which are separated by introns ranging in size from about 300 bp to 3.3 kb. The total length of the gene is about 24.5 kb, estimated by adding up the sizes of the exons and introns. A comparison of the structure of the hLf gene with that of other species revealed that the hLf gene is more closely related to bLf than to mLf. The positions of the introns were well matched with those of the bLf gene except only for exons 14 and 15, wherein exon 14 of the hLf gene is one nt shorter while exon 15 is one nt longer than the bLf gene. All the exon-intron boundaries of the gene conformed to the GT/AG rule. In situ fluorescence hybridization indicated that the hLf gene was mapped in the region 3p21.3.

Molecular characterization of the Drosophila melanogaster gene encoding the pterin 4alpha-carbinolamine dehydratase

We have isolated and characterized the cDNA and the genomic DNA encoding Drosophila melanogaster pterin 4alpha-carbinolamine dehydratase (PCD). The amino acid sequence deduced from the cDNA sequence was very similar to those of PCDs previously reported in other species (19-57% identity). The protein coding region of the cDNA was expressed in E. coli as a histidine fusion protein, and the expressed protein proved to have PCD activity. The characterization of the Drosophila genomic clone revealed that the Drosophila PCD gene is interrupted by two introns. The potential promoter region, deduced from the determination of the transcription start point (tsp), lacks the distinct TATAAA box consensus sequence.

Expression of Tcf-1 mRNA and surface TCR-CD3 complexes are reduced during apoptosis of T cells

When a T cell hybridoma, 70.7, was treated with a Ca2+ ionophore (A23187), apoptotic cell death was induced. Interestingly, we observed that the expression of Tcf-1, a T cell-specific transcription factor, mRNA was reduced by approximately 5-fold in the A23187-treated apoptotic cells compared to an ethanol-treated control. The hybridoma cells, however, did not display such a reduced expression of Tcf-1 mRNA upon treatment with buthionine sulfoxide, which is known to induce a necrosis-like cell death. When another T cell hybridoma, KMIs-8.3.5, was treated with A23187 and phorbol myristate acetate, which leads to activation-induced apoptosis, Tcf-1 expression was again greatly reduced. However, a mutant line (KCIT1-8.5) derived from KMIs-8.3.5, which produces IL-2 upon activation and is resistant to apoptosis, did not show such reduction in Tcf-1 expression. We also showed that the reduced expression level of CD3epsilon mRNA and surface TCR-CD3 complex in apoptotic T cells is caused by the reduced expression of Tcf-1. When 70.7 cells were transfected with a plasmid DNA pSVtcf-1, in which Tcf-1 gene expression is driven by the SV40 promoter, such reduction of the Tcf-1 mRNA and the surface expression of the TCR-CD3 complex were not observed upon apoptosis induction. Our results suggest that the reduced expression of Tcf-1 is specific for the apoptotic, but not for the activating, process of T cells and is also responsible for the reduced surface expression of the TCR-CD3 in apoptotic T cells.

A glycosidase antibody elicited against a chair-like transition state analog by in vitro immunization

Antibodies were generated against the positively charged chair-like glycosidase inhibitor nojirimycin by in vitro immunization. A number of catalytic antibodies were isolated, one of which catalyzes the hydrolysis of p-nitrophenyl beta-D-glucopyranoside 3 with a rate enhancement (kcat/kuncat) of 10(5) M over the HOAC-catalyzed reaction. The antibody discriminates modifications in the pyranoside ring of substrate 3 at the C2, C4, and the anomeric positions. The pH dependence of the reaction and chemical modification studies suggest the presence of an active-site Asp or Glu residue that may function as a general acid. This study further defines those requirements necessary to generate antibodies that efficiently cleave glycosidic bonds.

Near-field propagation of terahertz pulses from a large-aperture antenna

The near-field propagation behavior of terahertz (THz) pulses generated by a planar large-aperture photoconducting THz transmitter has been characterized. A simulation model based on Huygens-Fresnel diffraction theory has been developed that permits accurate prediction of the spatiotemporal profiles of the THz beam everywhere and gives excellent agreement with experimental measurements. Two key conclusions emerge from this research, namely, the realization that for practical laboratory setups one is always working in the near-field regime and that the proper temporal shape of the THz field at the antenna is one that rises rapidly but decays slowly.

In vitro metabolism of the new insecticide flupyrazofos by rat liver microsomes

1. The in vitro metabolism of the new insecticide flupyrazofos was studied using rat liver microsomes. Two metabolites were produced and identified as O,O-diethyl O-(1-phenyl-3-trifluoromethyl-5-pyrazoyl) phosphoric acid ester (flupyrazofos oxon) and 1-phenyl-3-trifluoromethyl-5-hydroxypyrazole (PTMHP) based on UV and mass spectral analysis. 2. Cytochrome P450 oxidatively converted flupyrazofos to flupyrazofos oxon, a major metabolite and phenobarbital-induced microsomes increased this desulphuration by 8-fold. 3. Flupyrazofos oxon was converted to PTMHP with a half-life of 47.8 min by chemical hydrolysis and this conversion also proceeded non-enzymatically under our microsomal incubation conditions.

[A human case of internal myiasis in Korea]

A 71-year old male patient was admitted in Inha hospital due to right facial palsy, quadriplegia and aphasia. This patient was operated to replace his heart values 7 years ago and has been treated with Coumarin, an anti-coagulant drug, to prevent the formation of thrombus in the heart. A number of fly maggots continuously crawled out from the nasogastric tube set up for supplying a liquid diet and patient's mouth for 2 days until his death in the intensive care unit of hospital. These maggots were about 11.5 mm long on the average and identified as genus Lucilia belonging to family Calliphoridae. The lesion of this myiasis case might be regarded in the gastro-intestinal system of patient. This is the first report of an internal myiasis case in Korea.

Micrococcal nuclease digestion of nuclei reveals extended nucleosome ladders having anomalous DNA lengths for chromatin assembled on non-replicating plasmids in transfected cells

The chromatin structures of a variety of plasmids and plasmid constructions, transiently transfected into mouse Ltk- cells using the DEAE-dextran procedure, were studied by micrococcal nuclease digestion of nuclei and Southern hybridization. Although regularly arranged nucleosome-like particles clearly were formed on the transfected DNA, the nucleosome ladders, in some cases with 13-14 bands, were anomalous. Most often, a ladder of DNA fragments with lengths of approximately 300, 500, 700, 900 bp, etc. was generated. In contrast, typical 180-190 bp multiples were generated from bulk cellular or endogenous beta-actin gene chromatin. Very similar results were obtained with all DNA's transfected, and in a variety of cell lines, provided that plasmid replication did not occur. Additionally, after digestion of nuclei, about 90% of the chromatin fragments that contained transfected DNA sequences could not be solubilized at low ionic strength, in contrast with bulk cellular chromatin, suggesting association with nuclear structures or nuclear matrix. The remaining 10% of transfected DNA sequences, arising from soluble chromatin fragments, generated a typical nucleosome ladder. These results are consistent with the idea that assembly of atypical chromatin structures might be induced by proximity to elements of the nuclear pore complex or by nuclear compartmentalization.

A follow-up study using iodine-131 metaiodobenzylguanidine imaging in a patient with neuroblastoma

A new radiopharmaceutical, I-131 metaiodobenzylguanidine (I-131 MIBG) was used to determine the location and to follow-up tumors in a 13-month-old girl with neuroblastoma. I-131 MIBG imaging revealed both a primary abdominal tumor and a distant metastatic orbital tumor. Follow-up study with I-131 MIBG imaging demonstrated significant resolution of tumors after external radiotherapy and chemotherapy. I-131 MIBG imaging is a simple, safe, and specific method of determining the location of tumors and also is clinically useful in the evaluation and management of patients with neuroblastoma.