pUC12-W1: a plasmid vector for the study of cloned DNA conformation

pUC12-W1 is a new cloning vector for the study of torsion-induced structural transitions of insert DNA. It was derived from pUC12 by deleting three A + T-rich sequences which can undergo structural transitions when torsionally stressed. Transitions at these sites have low energy of activation and undefined structures. They complicate studies on transitions of DNA inserts by diverting torsional force and causing the vector to be undefined in helical and energetic terms. The new vector pUC12-W1, from which these segments have been deleted, will facilitate studies of torsion-induced structural transitions of insert DNA.

[Flow cytometer (FCM) in biological characteristics of nasopharyngeal carcinoma xenografts in nude mice]

Tumor tissue from a patient with nasopharyngeal carcinoma was transplanted to nude mice (BALB/c) and had successfully been maintained through ten passages. The nude mice tumor and the primary human tumor were assayed by FCM for the DNA content in addition to conventional pathological examination, chromosome analysis and EBV assay. The tumor incidence in the different passages showed a marked change ranging from 25% to 81% with a mean value of 52% which tended to increase, however. The doubling time of six tumors in the ninth passage showed no great change 6-12 weeks after transplantation with a mean about 4.3 days. But at week 12, there was a significant difference between each tumor volume, ranging from 438 to 1,998 mm3. By FCM, it was found that the DNA index remained constant in both the primary and nude mice tumors. Among the nude mice tumors in different passages, the distribution of various phase cells in cell cycle was similar to that of the primary tumor. In conclusion, the use of FCM to assay the cellular DNA content in nude mice tumor is rapid and sensitive. It is helpful, for the nude mice tumor, in identifying stability of the biological characteristics and in studying of the mechanism of chemotherapy and radiotherapy in the future.

Cadmium- and mercury-resistant Bacillus strains from a salt marsh and from Boston Harbor

Bacteria resistant to cadmium or mercury or both were isolated from the Great Sippewissett Marsh (Cape Cod, Mass.) and from Boston Harbor. Many of these metal-resistant isolates were gram-positive aerobic sporeformers, although not necessarily isolated as spores. Although several of the isolated strains bore plasmids, cadmium and mercury resistances appeared to be, for the most part, chromosomally encoded. DNA sequence homology of the gram-positive cadmium- and mercury-resistant isolates was not demonstrable with metal resistance genes from plasmids of either gram-positive (pI258) or gram-negative (pDB7) origin. Cadmium resistance of all the marsh isolates tested resulted from reduced Cd2+ transport. On the other hand, three cadmium-resistant harbor isolates displayed considerable influx but no efflux of Cd2+. Hg-resistant strains detoxified mercury by transforming Hg2+ to volatile Hg0 via mercuric reductase.

Enhanced cAMP response to vasopressin in the CCT of DOCA-Na hypertensive rats

We characterized altered adenosine 3',5'-cyclic monophosphate (cAMP) regulation in deoxycorticosterone acetate (DOCA)-Na hypertensive rats using endogenous cAMP accumulation in the intact cell system of microdissected renal tubule fragments. Increased cAMP accumulation in response to vasopressin (VP) in cortical collecting tubules (CCT) began on day 5 (67%) after exposure to DOCA-Na and increased by 320% on day 42. Increased blood pressure began after day 7 and polyuria after day 17. The increased response to VP was DOCA dependent and appears to be exaggerated by dietary NaCl. Anatomic and hormone specificity studies were done on days 21-30. These included cAMP responses to prostaglandin E2, parathyroid hormone, thyrocalcitonin, VP, and isoproterenol in the CCT. The cAMP response to VP was measured in the glomerulus, proximal convoluted tubule, thin descending limb of Henle, medullary thick ascending limb of Henle, cortical thick ascending limb of Henle, medullary collecting tubule, and CCT. The supersensitivity occurred only to VP and only in the CCT. Thus this alteration in the VP response is anatomic and hormone specific and does not appear to be an acute effect of DOCA, since it was not present on day 1 and on day 3 of DOCA exposure. DOCA-Na hypertension is VP dependent. A specific exaggerated cAMP response to this hormone in the CCT would be expected to cause increased sodium retention. Whether increased sodium retention at this site contributes to hypertension in the DOCA-Na rat is unknown.

High performance liquid chromatography of integral glycoproteins of peripheral nerve myelin

Peripheral nerve myelin contains a large quantity of integral glycoproteins, such as PO and PASII protein. The present paper reports a fast and sensitive method for separation of these glycoproteins. High performance liquid chromatography (HPLC) with TSK-GEL 3000 SW column in the presence of sodium dodecyl sulfate (SDS) or lithium dodecyl sulfate (LDS) was used. Whereas the separation of PO and PASII was inadequate with low concentrations of the detergent, better separation profiles were obtained with high concentrations (1-2%) of the detergent in 0.1 M phosphate buffer. The two glycoproteins were able to be purified by rechromatography. High concentration of the detergent presumably diminished interaction between these glycoproteins. LSD-phosphate, SDS-lithium citrate or SDS-Tris buffer as an eluent was also compared with SDS-phosphate system. This method will be applicable to the detection and purification of proteins from myelin or other organelles.

Raman spectra of the model B-DNA oligomer d(CGCGAATTCGCG)2 and of the DNA in living salmon sperm show that both have very similar B-type conformations

Raman spectra were obtained from aqueous solutions of the deoxyoligonucleotide d(CGCGAATTCGCG)2 (I), which has been suggested as a model for B-type DNA conformation. These spectra were compared with the Raman spectra of the aqueous solutions of several DNAs of natural origin taken under identical solution conditions. Since the model sequence has a high percent GC (66%), the Raman spectrum was compared with the Raman spectrum of the DNA from Micrococcus lysodeikticus (72% GC), and the spectra of the two different DNAs were found to be rather similar in both 50 mM salt and 6 M salt solutions. Computer-aided band-shape analysis of the backbone vibrational region of the Raman spectra shows the existence of several bands corresponding to different furanose ring puckers. This appears to indicate a heterogeneity of furanose ring pucker in both the model dodecamer and the native DNA. Significant differences were found in the intensity of the conformational marker band at 810 cm-1, which indicates corresponding differences in furanose ring pucker heterogeneities in these two high GC content DNAs. The Raman spectrum of the dodecamer (I) was used to analyze the Raman spectrum of the DNA inside the head of living intact salmon sperm. Sperm spectra were taken with both our conventional Raman spectrograph and a newly developed intracavity laser Raman microscope system. Although the DNA in the sperm head is required by packing considerations to be in a highly compact and condensed state, the Raman spectra of the intact sperm are almost identical with that of the model dodecamer (I) if the difference in base composition is taken into account.(ABSTRACT TRUNCATED AT 250 WORDS)

60Co radiation-induced transformation to anchorage independence of fibroblast from normal persons and patients with inherited predisposition to retinoblastoma

Retinoblastoma (RB), cancer of the retina, occurs in an inherited form which not only predisposes the patient to bilateral RB, but also to the risk of developing secondary tumors of mesenchymal origin (osteosarcomas and fibrosarcomas). These tumors often arise in areas that were exposed to ionizing radiation during therapy and fibroblasts derived from patients with hereditary RB have been reported to be more sensitive than normal to the killing effects of ionizing radiation. Therefore, we compared diploid fibroblast cell lines derived from two hereditary RB patients (aged 1 and 3 years) with those of three normal persons (two newborns and a 2 year old) for their sensitivity to ionizing radiation-induced transformation to anchorage independence. The target cells were exposed to 60Co radiation (1.0-3.5 Gy), allowed to undergo an expression period (4-5 population doublings in 5 days), and assayed for ability to form colonies in 0.33% agar. There was no detectable difference between the RB cells' and the normal cells' response to the transforming action of the 60Co. Both kinds of cells showed a linear, dose-dependent increase in anchorage-independent cells from 100 to 800/10(6) cells assayed.

Electrophysiological interactions of isomers of cyclazocine with the phencyclidine antagonist metaphit in rat cerebellar Purkinje neurons

Metaphit, 1-(1-(3-isothiocyanatophenyl) cyclohexyl) piperidine, an analog of phencyclidine (PCP) has been shown previously to selectively block PCP receptors and to irreversibly antagonize the depressant effect of PCP in cerebellum. In this study, we examined the electrophysiological interactions of metaphit and naloxone with stereoisomers of cyclazocine, an agent known to have analgesic and psychotomimetic activity in behavioral studies, effects that have been ascribed to opiate and PCP receptor activity. A dose-dependent and reversible slowing of Purkinje neuron discharge was seen with local application of (+)- or (-)-cyclazocine. We found that the blockade of (-)-cyclazocine effects required both high doses of naloxone and the presence of metaphit, whereas the responses to (+)-cyclazocine were blocked by metaphit alone on most cerebellar Purkinje neurons. These findings suggest that the depressant reaction of (+)-cyclazocine in cerebellar Purkinje neurons is primarily mediated through PCP receptors. (-)-Cyclazocine responses, on the other hand, appear to be due to activity at both PCP and kappa opioid receptors.

Methylation patterns of HLA-DR alpha genes in six mononuclear cell lines

The relationship between DNA methylation and HLA-DR alpha gene expression was investigated in six mononuclear cell lines. RPMI-4265 (B cell) and HUT-78 (T cell) constitutively express HLA-DR. HL-60 (myelomonocyte) and U-937 (monocyte) can be induced to express HLA-DR. Jurkat and Molt-4 (T cells) do not and cannot be induced to express HLA-DR. Based on the known nucleotide sequence of the HLA-DR alpha gene, methylation-sensitive restriction endonucleases Msp I, Hpa II, Hha I, Ava I, Hae II, and Sma I were used to detect the CpG methylation in three regions of the HLA-DR alpha gene: the 5'flanking region, the exon 1 region, and the coding region containing exons 2, 3, 4, and 5. This precise mapping of CpG methylation yielded no correlation between DNA hypomethylation and HLA-DR alpha gene expression. In all cell lines, exon 1 region is hypomethylated, whereas 5' and coding regions are hypermethylated. Whereas hypermethylation of the coding region does not block transcription, hypomethylation of the exon 1 region may be essential but is clearly not sufficient for HLA-DR alpha gene transcription. This exon 1 region demethylation may result in an open (deoxyribonuclease I hypersensitive) chromatin conformation around the promoter where trans-acting regulatory factors presumably bind and initiate HLA-DR alpha transcription. In the course of this study, a novel Msp I polymorphism in the intron 1 of the HLA-DR alpha gene was found.

Phosphate inhibition of the copper- and zinc-containing superoxide dismutase: a reexamination

Phosphate was reported to be an inhibitor of copper- and zinc-containing superoxide dismutase (SOD) [de Freitas, D.M., & Valentine, J.S. (1984) Biochemistry 23, 2079-2082]. Thus SOD activity, in 50 mM 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) (pH 7.4), was decreased by approximately 50% when the assay was made 10 mM in phosphate, and the ionic strength was adjusted with sodium fluoride. The inhibitory effect of phosphate was attributed to the neutralization of the positive charge on the guanidino residue of Arg-141. We have reexamined the effects of phosphate inhibition of SOD and found that the enzyme has identical activity in phosphate or HEPES buffer when the ionic strength is adjusted with NaBr. The putative inhibitory effect of phosphate appears to have been due to fluoride inhibition of the superoxide generating system of xanthine/xanthine oxidase. We have confirmed this result by using a photochemical generation of O2- in addition to the enzymatic generation of O2-. Chemical modification of the lysine residues to homoarginines does not affect the activity of the enzyme and does not impart a phosphate sensitivity. Chemical modification with phenylglyoxal caused approximately 80% inactivation of the native enzyme and 90% inactivation of the O-methylisourea-modified enzyme. Our results suggest that phosphate does not inhibit the copper- and zinc-containing superoxide dismutase (Cu,Zn-SOD) beyond the expectations of its effect on ionic strength.

Functional changes in rat-liver mitochondria during the early phase of burn injury

Using succinate as a substrate, the respiratory control ratios of liver mitochondria from burned male Sprague-Dawley rats with full skin thickness burns covering 20 per cent of the body surface area were increased at 15, 30, 45 and 60 min after burn, the peak being at 30 min post-burn. A sham group acted as control. In comparison with the sham group, the specific activity of succinic dehydrogenase was slightly decreased and the activities of cytochromes b and c + c were decreased significantly 30 min after burning. All the results suggest a lack of increased metabolic activity during the early phase of burn injury.

Fibroblasts from patients with inherited predisposition to retinoblastoma exhibit normal sensitivity to the mutagenic effects of ionizing radiation

Retinoblastoma (RB) is a cancer of the retina which characteristically occurs in early childhood. Bilateral RB is an inherited form of this disease. Such patients are at greatly increased risk of subsequently developing second tumors in mesenchymal tissue, especially in areas exposed to ionizing radiation therapy. Fibroblasts from bilateral RB patients have been reported to be more sensitive than normal fibroblasts to the cytotoxic effects of ionizing radiation. Because xeroderma pigmentosum patients have a hereditary predisposition to UV-induced cancer and the cells of such patients are abnormally sensitive to the cytotoxic and mutagenic effects of UV radiation, we compared fibroblasts from 6 bilateral RB patients and 3 normal individuals for their sensitivity to the mutagenic effects of cobalt 60, using resistance to 6-thioguanine (TG) as the genetic marker. The results showed no statistically significant difference between the two types of cell lines. The slope of the weighted least squares line representing the frequency of TG-resistant cells induced in the RB populations as a function of dose was 17 +/- 6 (S.E.)/10(6) cells/Gy with an intercept of 0.09 Gy; that for the normal cells was 17 +/- 7/10(6) cells/Gy with an intercept of 0.14 Gy. We also compared 8 bilateral RB cell lines and 9 age-matched normal cell lines for their sensitivity to the cytotoxic effect of 60Co, using survival of colony-forming ability. The cloning efficiency of the unirradiated RB cell lines ranged from 22% to 76% with an average of 52%; that of the normal cell lines from 21% to 89% with an average of 64%. The results showed the RB cells were somewhat more sensitive than the normal cells. The mean D0 for the RB cell lines ranged from 0.99 +/- 0.01 (S.E.) to 1.69 +/- 0.04 Gy with a weighted average of 1.44 +/- 0.08 Gy; that of the normal cell lines ranged from 1.42 +/- 0.17 to 2.24 +/- 0.10 Gy, with a weighted average of 1.79 +/- 0.11 Gy. The difference in means was estimated to be 0.34 +/- 0.14. The mean for the RB cell lines is statistically significantly lower than the mean for the normal cell lines, at a significance level ca. 1%.

Multiple phosphorylation sites of rat liver glycogen synthase

Rat liver glycogen synthase was purified to homogeneity by an improved procedure that yielded enzyme almost exclusively as a polypeptide of Mr 85,000. The phosphorylation of this enzyme by eight protein kinases was analyzed by cleavage of the enzyme subunit followed by mapping of the phosphopeptides using polyacrylamide gel electrophoresis in the presence of SDS, reverse-phase high-performance liquid chromatography and thin-layer electrophoresis. Cyclic AMP-dependent protein kinase, phosphorylase kinase, protein kinase C and the calmodulin-dependent protein kinase all phosphorylated the same small peptide (approx. 20 amino acids) located in a 14 kDa CNBr-fragment (CB-1). Calmodulin-dependent protein kinase and protein kinase C also modified second sites in CB-1. A larger CNBr-fragment (CB-2) of approx. 28 kDa was the dominant site of action for casein kinases I and II, FA/GSK-3 and the heparin-activated protein kinase. The sites modified were all localized in a 14 kDa species generated by trypsin digestion. Further proteolysis with V8 proteinase indicated that FA/GSK-3 and the heparin-activated enzyme recognized the same smaller peptide within CB-2, which may also be phosphorylated by casein kinase 1. Casein kinase 1 also modified a distinct peptide, as did casein kinase II. The results lead us to suggest homology to the muscle enzyme with regard to CB-1 phosphorylation and the region recognized by FA/GSK-3, which in rabbit muscle is characterized by a high density of proline and serine residues. A striking difference with the muscle isozyme is the apparent lack of phosphorylations corresponding to the muscle sites 1a and 1b. These results provide further evidence for the presence of liver- and muscle-specific glycogen synthase isozymes in the rat. That the isozymes differ subtly as to phosphorylation sites may provide a clue to the functional differences between the isozymes.

Epidemiological studies on hemorrhagic fever with renal syndrome in China

Hemorrhagic fever with renal syndrome (HFRS) has been reported from greater than 20 provinces in China. The number of reported cases has increased markedly in recent years and surpassed 80,000 human cases in 1983. All of the cases reported before 1981 were from rural areas and were attributed to Apodemus rats. In 1981, outbreaks of cases associated with house rats were first reported. Cases associated with Apodemus agrarius were more severe than those associated with the house rat Rattus norvegicus. The rate of inapparent infection in the rural population of areas endemic for Apodemus-associated disease was lower than that of Rattus-associated urban disease. After the onset of the disease, IgG antibody levels increase rapidly, peak after one week, and persist for as long as 25 years. Lung tissues from 16 species of rodent, from two species of sorex, and from cats and weasels in the epidemic areas have been found to carry antigen. A. agrarius, Apodemus peninsulae, and R. norvegicus serve as the main reservoirs of HFRS in rural areas, forest areas, and urban areas, respectively.

Developmental differences in the effect of natural feeding on early enteric mucosal growth of guinea pigs

In contrast to observations in other species, neither enteric mucosal weight, protein content, nor DNA content of either the suckled or artificially fed guinea pig changes over the first 24 h following term birth. In guinea pigs delivered 5 days prematurely, however, statistically significant increases in proximal enteric mucosal mass (38%), protein content (51%), and DNA content (35%) occur in suckled animals over the first 24 h of life but not in artificially fed animals. These observations illustrate that the enteric mucosal hyperplasia secondary to natural feeding, quantitatively and temporally, is species-specific and suggest that this effect is manifested only during a finite period of intestinal development. They raise doubts, therefore, concerning the importance of early enteric mucosal hyperplasia in adaptation of all species to extrauterine life.