Family of the major cold-shock protein, CspA (CS7.4), of Escherichia coli, whose members show a high sequence similarity with the eukaryotic Y-box binding proteins

The cspA is a gene of Escherichia coli, whose expression is specifically induced at low temperatures to a level of 13% of total protein synthesis. The CspA protein consisting of 70 amino acid residues has high sequence similarity with eukaryotic Y-box DNA-binding proteins. We found two independent clones from the Kohara miniset phage collection, which hybridized with a DNA fragment containing cspA. DNA sequencing of these clones confirmed that the two genes are highly homologous to cspA. One designated cspB is mapped at 35 min on the E. coli chromosome and encodes a 71-residue protein with 79% identity to CspA, while the other, cspC, is mapped at 40 min and encodes a 69-residue protein with 70% identity. In addition, a DNA sequence upstream of the clpA gene at 19 min published elsewhere contains an open reading frame for a 74-residue protein with 45% identity to CspA. All csp genes were fused in the coding regions with the lacZ gene, and the expression of beta-galactosidase was examined for these hybrid genes upon cold shock. A similar cold-shock induction to cspA was observed for cspB but not cspC and cspD. These results indicate that E. coli has a family of the cspA gene, some of which are induced by cold shock.

Corrective responses to loss of ground support during walking. II. Comparison of intact and chronic spinal cats

1. The preceding study described a corrective response in cats when one hind leg steps into a hole. In this investigation we examine the extent to which this behavior is organized at the spinal level by comparing the responses elicited in intact and chronic spinal cats. 2. Adult cats were trained to step bipedally with their hind legs on a treadmill. After training, the responses to stepping into a hole cut in the treadmill belt were monitored with a video recorder and by recording electromyograms from muscles in both hind legs. The responses to stepping into the hole were also recorded in chronic spinal cats that had recovered the ability to step with their hind legs a few weeks after spinalization. 3. The behavioral responses in the two groups of animals differed in two respects. First, the latency of the onset of the flexion movement to remove the foot from the hole was shorter in intact animals (70-150 ms in intact vs. 130-350 ms in spinal animals). Second, the flexion movement in the intact animals was stronger. The exaggerated flexion movement in intact animals lifted the paw well clear of the hole and allowed support to be regained on the treadmill belt. The weaker flexion movement in spinal animals was usually insufficient to lift the paw completely from the hole. 4. Differences in the motor patterns recorded from flexor muscles during the corrective response in intact and spinal animals correspond with the differences in the kinematics. First, the onset of flexor activity after the foot entered the hole was delayed by approximately 100 ms in spinal animals relative to intact animals. Second, in intact animals the magnitudes of flexor bursts were increased relative to the flexor bursts associated with the swing phase during stepping, whereas in spinal animals flexor bursts during the corrective response resembled those occurring during swing. 5. Similarities in the duration and the timing of bursts in different flexor muscles in intact and spinal animals during the corrective response and during swing indicated that the corrective response involves activation of the spinal system that normally produces swing phase flexor activity. We conclude that activation of this system is facilitated by input from supraspinal structures during the corrective response in intact animals. 6. In all intact animals and three of five spinal animals, support of the hindquarters when the foot entered the hole was maintained by the contralateral leg.(ABSTRACT TRUNCATED AT 400 WORDS)

Use of the rep technique for allele replacement to construct new Escherichia coli hosts for maintenance of R6K gamma origin plasmids at different copy numbers

Escherichia coli hosts were constructed for maintenance of vectors containing the gamma replication origin of the R6K plasmid (oriRR6K gamma) at different copy numbers (15 or 250/cell). Such vectors require the trans-acting II protein (the pir gene product) for replication. New hosts carry pir+ or pir-116 on the chromosome within uidA, the E. coli gene encoding beta-glucuronidase. They were made using the rep technique for allele replacement and KmR M13 delta uid A::pir+ or M13 delta uidA::pir-116 phage. Because M13 cannot replicate in a rep mutant, KmR transductants arose by integration into the chromosomal uidA locus. Segregants lacking M13 sequences (which were selected as deoxycholate-resistant (DocR) ones) frequently contained delta uidA::pir+ or delta uidA::pir-116 on the chromosome. In principle, this procedure could be used for the introduction of any foreign gene into any nonessential gene on the E. coli chromosome. The delta uidA::pir+ and delta uidA::pir-116 loci were subsequently transferred to a variety of E. coli strains. One such strain is a suppressor-negative one that is especially useful for transposon (Tn) mutagenesis. This strain has an integrated RP4 derivative for conjugative transfer of oriRR6K gamma plasmids also containing oriT from RP4. In addition, new oriRR6K gamma, oriT+ vectors carrying the TcR-encoding genes tetAR from Tn10 are described. These can be used for allele replacement by conjugative transfer of an oriRR6K gamma, oriT+, tetAR plasmid containing a mutated gene into a non-pir recipient and by subsequent selection for Tc-sensitive exconjugants.

Effects of lead on root growth, cell division, and nucleolus of Allium cepa

The effects of different concentrations of lead nitrate on root growth, cell division, chromosome morphology and nucleolus in root tip cells of Allium cepa were studied. The concentrations of lead nitrate (Pb(NO(3))(2)) were 10(-7), 10(-6), 10(-5), 10(-4), 10(-3) and 10(-2) m. It was observed that lead reduces root growth and causes mitotic irregularities, including c-mitosis, anaphase bridges, and chromosome stickiness. Also, interphase cells with micronuclei, irregularly shaped nuclei and nuclei with decomposed nuclear material were noticed. The c-mitotic effect reached its maximum in the meristem at above 10(-4) m Pb, when practically almost all the anomalous dividing cells are of this type. After treatment with Pb, there were many similar silver-stained particulate materials scattered in the nucleus in short, rounded meristem cells and in long, oblong root cap cells.

Effects of designer drugs on the chicken embryo and 1-day-old chicken

The present study was conducted to examine the effects of d-amphetamine and the designer drugs 3,4-methylenedioxymethamphetamine (MDMA), N-methyl-3,4-methylenedioxyphenyl-3-butamine (HMDMA), 3,4-methylenedioxyphenyl-2-butanamine (BDB), 3,4-methylenedioxyphenyl-1-ethanamine (MDM1EA) in the chick embryo and the young chicken. HMDMA and MDM1EA had no effect on motility on day 14 of embryogenesis, while MDMA, BDB, and d-amphetamine decreased embryonic motility at one or more doses. On day 1 posthatch, chickens were challenged with cumulative injections of water or the same drug that they had received in ova. With the exception of MDM1EA, all of the drugs produced effects such as distress vocalization, wing extension, tremor, flat body posture, bursting forward movements, loss of righting reflex, and convulsant-like kicking. Pretreatment with drug in ova resulted in tolerance to certain drug effects and supersensitivity to other drug effects. Furthermore, BDB significantly decreased hatchability, MDM1EA decreased body weight, and HMDMA decreased liver weight. Further studies are needed to determine the mechanism(s) of toxicity in this species.

Cloning of the PABA peptide hydrolase alpha subunit (PPH alpha) from human small intestine and its expression in COS-1 cells

PABA peptide hydrolase (PPH) from human enterocytes is comprised of two subunits, alpha and beta. PPH alpha is over 70% identical to meprin, a protease isolated from mouse and rat kidney. The enzyme shows a modular organization in that it contains an astacin protease domain, an adhesive domain, an EGF-like domain, an a putative C-terminal membrane spanning domain. Expression of a chimeric meprin-PPH alpha cDNA in COS-1 cells led to the synthesis of immature, transport-incompetent homodimers. In addition, complex glycosylated forms were detected in the culture medium, suggesting that the enzyme is secreted after proteolytic removal of the membrane anchor.

Overexpression of cyclin D1 in rat fibroblasts causes abnormalities in growth control, cell cycle progression and gene expression

Cyclin D1, a putative G1 cyclin, has been implicated in cell cycle control. The human cyclin D1 gene is located on chromosome 11q13 where DNA rearrangement and amplification have been detected in several types of human cancer. Previous studies demonstrated that the cyclin D1 gene is not only rearranged or amplified but also overexpressed in some of these human tumors and tumor-derived cell lines. To further address the roles of cyclin D1 in cell cycle control and tumorigenesis, we have stably overexpressed the human cyclin D1 cDNA in Rat6 embryo fibroblasts by using retrovirus mediated transduction. The cyclin D1 protein was overproduced about 10-fold and was localized predominately in the nucleus. Cyclin D1 overexpressing cells displayed a decrease in the duration of the G1 phase, decreased cell size, and induced tumors when injected into athymic (nude) mice. In addition, overexpression of cyclin D1 in Rat6 cells perturbed the expression of several cellular growth-related genes including c-myc, c-jun, and cyclin A, but not cyclin D3. Taken together, these results indicate that deregulated expression of the cyclin D1 gene can cause disturbances in cell cycle control and gene expression and also enhance tumorigenesis.

Gaze-related activity of putative inhibitory burst neurons in the head-free cat

1. Previous studies in the cat have demonstrated that output neurons of the superior collicular as well as brain stem omnipause neurons have discharges that are best correlated, not with the trajectory of the eye in the head but, with the trajectory of the visual axis in space (gaze = eye-in-head + head-in-space) during rapid orienting coordinated eye and head movements. In this study, we describe the gaze-related activity of cat premotor "inhibitory burst neurons" (IBNs) identified on the basis of their position relative to the abducens nucleus. 2. The firing behavior of IBNs was studied during 1) saccades made with the head stationary, 2) active orienting combined eye-head gaze shifts, and 3) passive movements of the head on the body. IBN discharges were well correlated with the duration and amplitude of saccades made when the head was stationary. In both head-free paradigms, the behavior of cat IBNs differed from that of previously described primate "saccade bursters". The duration of their burst was better correlated with gaze than saccade duration, and the total number of spikes in a burst was well correlated with gaze amplitude and generally poorly correlated with saccade amplitude. The behavior of cat IBNs also differed from that of previously described primate "gaze bursters". The slope of the relationship between the total number of spikes and gaze amplitude observed during head-free gaze shifts was significantly lower than that observed during head-fixed saccades. 3. These studies suggest that cat IBNs do not fit into the categories of gaze-bursters or saccade-bursters that have been described in primate studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrically pumped mode-locked vertical-cavity semiconductor lasers

We demonstrate what is to our knowledge the first electrically pumped mode-locked vertical-cavity surfaceemitting laser. The lasing threshold current is 15 mA with a 1% output coupler. The output pulse width is 80 ps at a repetition rate of 1 GHz.

The backbone structure of the major cold-shock protein CS7.4 of Escherichia coli in solution includes extensive beta-sheet structure

CS7.4 is the major cold-shock protein specifically expressed to a level as high as 13% of the total cellular protein within the first hour when Escherichia coli cell culture is shifted from 37 to 15 degrees C [Goldstein et al. (1990) Proc. Natl. Acad. Sci. USA 87, 283-287]. It consists of 70 amino acid residues with a very high content of aromatic residues. CS7.4 was overproduced and purified to homogeneity. Its secondary structure was analyzed by examining circular dichroism at both the far and near-UV regions; the results suggest that the protein is largely beta-sheet in conformation. The predominance of beta-sheet structure in the protein was confirmed by using Fourier-transform infrared spectroscopy. A folded compact conformation was also verified by fluorescence emission spectroscopy. We evaluated Tm, delta H, and delta S from the thermal denaturation profile of the protein. Unusual spectral features observed in the far-UV region are attributed to the high content of aromatic residues. The protein is relatively small and contains no disulfide bonds. However, it is surprisingly stable to heat denaturation.

Amplification and overexpression of cyclin D1 in human hepatocellular carcinoma

Amplification of the chromosome 11q13 region occurs in several types of human cancer including esophageal, breast, lung, bladder and hepatocellular carcinoma (HCC). The gene cyclin D1 maps to this region in close proximity to two proto-oncogenes hst-1 and int-2. We previously demonstrated that cyclin D1 was not only amplified but also overexpressed in about 30% of human esophageal cancers. To investigate the role of cyclin D1 in human hepatocellular carcinoma (HCC), DNA from 30 HCC and 5 control liver tissues from Taiwan and also the HCC cells lines HepG2 and Hep3B, were examined for amplification of the cyclin D1 gene. A 3 to 20-fold amplification was found in 4 of the 30 (13%) HCC samples but not in any of the 5 control tissues or the 2 cell lines. Immunohistochemical analysis of cyclin D1 indicated overexpression of this protein in tumors that displayed gene amplification. Weak or negative staining was observed in the other HCC samples as well as in the control tissues and cell lines. These data suggest that increased expression of cyclin D1 may play an important role in the development of a subset of human HCC, perhaps by perturbing normal control of the cell cycle.

Cloning, expression, and chromosomal localization of the mouse meprin beta subunit

Meprins are plasma membrane homo- or hetero-oligomeric metalloendopeptidases that contain glycosylated alpha and/or beta subunits. This paper reports the cloning and sequencing of the mouse kidney beta subunit. The primary translation product is composed of 704 amino acids which includes a transient signal sequence of 20 amino acids at the NH2 terminus. The protease domain (Asn-63 to Leu-260) contains the putative zinc-binding motif characteristic of metalloendopeptidases of the "astacin family." The COOH terminus contains an epidermal growth factor-like domain, a potential membrane-spanning domain, and an additional 26 amino acids. The beta subunit has an overall 42% identity to the alpha subunit, however, a 56-amino acid segment near the COOH terminus of alpha is missing in beta, and the putative transmembrane and cytoplasmic domains of the subunits share no significant sequence similarity. NH2-terminal analyses of detergent-solubilized mature forms revealed that, unlike alpha, the prosequence (Leu-21 to Lys-62) is not removed from the beta subunit. Northern blot analysis revealed a 2.5-kilobase message for the beta subunit in the kidney and intestine of C57BL/6 and C3H/He mice. The gene for the beta subunit was localized to mouse chromosome 18. These studies indicate that alpha and beta probably derived from a common ancestral gene, but have evolved so that their genes are on two different chromosomes, and their tissue-specific expression and post-translational processing differ.

Altered expression of the cyclin D1 and retinoblastoma genes in human esophageal cancer

We have examined DNA from four human esophageal carcinoma cell lines and 50 primary esophageal carcinomas obtained from China, Italy, and France for amplification of the cyclin D1 gene. We also examined 36 of these 50 carcinomas for expression of the cyclin D1 and retinoblastoma (RB) proteins by immunohistochemistry. We found a 3- to 10-fold amplification of the cyclin D1 gene in 16 of the 50 (32%) tumors and in two of the four cell lines. Cyclin D1 protein was overexpressed in 12 of 13 tumors and the two cell lines that showed gene amplification when compared to normal controls. Studies on RB protein expression indicated that 6 of the 36 (17%) tumor samples examined and one cell line did not show detectable expression of this protein. The tumors and cell lines that had cyclin D1 gene amplification and overexpression exhibited normal levels of expression of RB protein. By contrast, the tumors and cell line that did not appear to express the RB protein did not show amplification of the cyclin D1 gene and expressed only low levels of the cyclin D1 protein (P = 0.03). These results suggest that the inhibitory effect of RB on cell cycle progression can be abrogated during tumor development either by loss of expression of the RB gene or by increased expression of the cyclin D1 gene.

Chloramphenicol induces the transcription of the major cold shock gene of Escherichia coli, cspA

A downshift in temperature or exposure of cells to certain inhibitors of translation has been shown to induce the synthesis of cold shock proteins in Escherichia coli. We characterized the induction of the major cold shock protein (CS7.4, the product of the cspA gene) of E. coli in response to a shift from 37 to 15 degrees C and in response to the addition of chloramphenicol at 15 degrees C. A pulse-labeling assay and primer extension experiments indicated that the cold shock treatment resulted in a transient increase in the level of the cspA transcript and a transient induction of CS7.4, while the addition of chloramphenicol resulted in a constitutive increase in the level of cspA transcript and constitutive production of CS7.4. The addition of rifamycin immediately following the temperature downshift or along with the addition of chloramphenicol repressed the transcription of cspA as well as the induced production of CS7.4. Furthermore, changes in the cspA mRNA level were coincident with changes in CS7.4 synthesis. These results indicate that the expression of cspA induced by cold shock and chloramphenicol is at the level of transcription but not at the level of translation. Measurement of the half-life revealed that the cspA mRNA induced by chloramphenicol was more stable than that induced by cold shock.

Relation of cardiovascular responses to mental stress and cardiac vagal activity in coronary artery disease

Forty-six patients with documented coronary artery disease were studied to examine the relation of cardiovascular reactivity to mental stress and cardiac vagal activity. Cardiac vagal activity was measured by means of frequency-domain analysis of heart rate variability with 48-hour out-of-hospital Holter monitoring. The amplitude of the high-frequency component (0.16 to 0.40 Hz) of heart rate variability is considered to be an index of cardiac vagal activity. Cardiovascular reactivity was measured in the laboratory during a 3-minute public speaking task. Results revealed that (1) the amplitude of the high-frequency component was significantly higher during sleep (24.6 +/- 11.3 ms) than during waking (18.2 +/- 8.0 ms) (p = 0.002); (2) compared to subjects with low diastolic blood pressure reactivity, those who displayed high diastolic blood pressure reactivity exhibited a significantly lower amplitude of the high-frequency component (19.2 +/- 6.9 vs 23.4 +/- 9.6 ms, p = 0.03). These results indicate that decreased cardiac vagal activity may contribute to the exaggerated diastolic blood pressure reactivity to mental stress in patients with coronary artery disease.

An essential yeast protein, CBF5p, binds in vitro to centromeres and microtubules

Yeast centromere DNA (CEN) affinity column chromatography has been used to purify several putative centromere and kinetochore proteins from yeast chromatin extracts. The single yeast gene (CBF5) specifying one of the major low-affinity centromere-binding proteins (p64'/CBF5p) has been cloned and shown to be essential for viability of Saccharomyces cerevisiae. CBF5 specifies a 55-kDa highly charged protein that contains a repeating KKD/E sequence domain near the C terminus, similar to known microtubule-binding domains in microtubule-associated proteins 1A and 1B, CBF5p, obtained by overexpression in bacterial cells, binds microtubules in vitro, whereas C-terminal deleted proteins lacking the (KKD/E)n domain do not. Dividing yeast cells containing a C-terminal truncated CBF5 gene, producing CBF5p containing only three copies of the KKD/E repeat, delay with replicated genomes at the G2/M phase of the cell cycle, while depletion of CBF5p arrests most cells in G1/S. Overproduction of CBF5p in S. cerevisiae complements a temperature sensitivity mutation in the gene (CBF2) specifying the 110-kDa subunit of the high-affinity CEN DNA-binding factor CBF3, suggesting in vivo interaction of CBF5p and CBF3. A second low-affinity centromere-binding factor has been identified as topoisomerase II.