IS91 transposase is related to the rolling-circle-type replication proteins of the pUB110 family of plasmids.
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Amino Acid Sequence↗
Biomedical subjects
F de la Cruz
Publications and source records attributed to F de la Cruz.
Risk factors associated with transcervical CVS losses.
Factors found to be associated with pregnancy loss after transcervical CVS were race (higher for non-white), history of spontaneous abortion, unplanned pregnancy, history of spotting or bleeding during the pregnancy prior to CVS, and placental position (higher for fundal or lateral locations). Whether the increase in loss risk is due to the factor, per se, or the factor plus the CVS cannot be determined due to the lack of appropriate control data.
Adult↗
Maternal phenylketonuria collaborative study, obstetric aspects and outcome: the first 6 years.
OBJECTIVE: The purpose of this study was to evaluate the efficacy of a phenylalanine-restricted diet in reducing fetal morbidity associated with maternal hyperphenylalaninemia in women of childbearing age with blood phenylalanine levels greater than 240 mumol/L (greater than 4 mg/dl) on an unrestricted diet. STUDY DESIGN: Two hundred thirteen pregnant women with hyperphenylalaninemia that resulted in 134 live births have been enrolled in the study. Outcome measures were subject to the chi 2 test, Fisher exact test, analysis of variance, t test, or Wilcoxon nonparametric test for analysis. RESULTS: Optimal fetal outcome appeared to occur when blood phenylalanine levels less than 600 mumol/L (less than 10 mg/dl) were achieved by 8 to 10 weeks' gestation and maintained throughout pregnancy (trimester averages of less than or equal to 360 mumol/L (less than or equal to 6 mg/dl). Initiation of dietary therapy during the third trimester of pregnancy appears to have little beneficial effect on the fetus. CONCLUSIONS: Preconceptual counseling and early entrance into a prenatal care program is essential in achieving optimal fetal outcome in women with hyperphenylalaninemia.
Congenital Abnormalities↗
The Hha protein from Escherichia coli is highly homologous to the YmoA protein from Yersinia enterocolitica.
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Amino Acid Sequence↗
DNA sequence of IS91 and identification of the transposase gene.
IS91 is a 1,830-bp insertion sequence that inserts specifically at the sequence CAAG or GAAC of the target and does not duplicate any sequence upon insertion (23). By transposon mutagenesis, we have identified open reading frame 426 (ORF426; bp 454 to 1731) as the putative ORF for the transposase. It displays a cysteine-rich, potential metal-binding domain in its N-terminal region. Adjacent to ORF426, there is an ORF (ORF121) which precedes and terminally overlaps ORF426 by one amino acid. Tn1732 insertions in ORF121 do not affect the transposition frequency. IS91 has sequence similarities to IS801 from Pseudomonas syringae. Their putative transposases are 36% identical, including conservation of the cysteine-rich cluster. The information concerning IS801 insertion specificity and target duplication has been reevaluated in the light of our results.
Amino Acid Sequence↗
Construction and properties of a family of pACYC184-derived cloning vectors compatible with pBR322 and its derivatives.
A family of cloning vectors derived from plasmid pACYC184 and, therefore, compatible with pBR322 and its derivatives (especially the pUC family of vectors), is described. They all contain a multiple cloning site (MCS) and the lacZ alpha reporter gene for easy cloning. They have been grouped in three sets: (i) six of the vectors contain a chloramphenicol-resistance (CmR)-encoding gene and each a different MCS with 16 unique restriction sites overall; (ii) another six vectors contain a kanamycin-resistance (KmR)-encoding gene and the same six MCS; and (iii) two CmR vectors that contain the SP6 and T7 promoters flanking the MCS and lacZ alpha reporter gene of pUC18/19.
Base Sequence↗
Alpha-haemolysin from E. coli. Purification and self-aggregation properties.
An improved, straightforward purification procedure for E.coli alpha-haemolysin has been developed. The protein exists in the form of large aggregates, held together mainly by hydrophobic forces. In the presence of urea or other chaotropic agents, the size of the aggregates decreases, while the specific activity is increased.
Bacterial Proteins↗
Structural and functional analysis of the origin of conjugal transfer of the broad-host-range IncW plasmid R388 and comparison with the related IncN plasmid R46.
We cloned and sequenced a 402 bp DNA segment containing the origin of conjugal transfer (oriT) of the IncW plasmid R388. Progressive deletions from each end of the sequence were assayed for oriT activity. Stepwise reductions in mobilization frequencies, representing the loss of functional elements, correlated with deletion of structural motifs in the sequence. A sequence of 330 bp of oriT was sufficient for efficient mobilization. The first 86 bp of the sequence contains five tandemly repeated DNA sequences of 11 bp, followed by a 10 bp perfect inverted repeat. Deletion of the first 95 bp reduced the frequency of transfer by a hundred-fold. The sequence between bp 183 and 218 was necessary and sufficient for low frequency mobilization and, thus, it was assumed to contain the nick site. This basis core was cloned as a 60 bp segment (from bp 176-236) that could be mobilized at low frequency. It includes two inverted repeats and a perfect integration host factor (IHF) consensus binding site. A third functionally important segment in oriT was located between bp 260 and 330. The DNA sequence of the oriT of R388 could be aligned with that of the broad-host-range IncN plasmid R46. Moreover, the relative positions of the three inverted repeats are also conserved. Overall sequence similarity was 52%, but was significantly higher in particular regions, which coincided with the functionally important segments mapped by deletion analysis. Conservation of these segments provided independent support for their essential role in oriT function.
Base Sequence↗
Tn5tac1 insertion polarity in Escherichia coli.
The Tn5-derived transposon Tn5tac1 carries the strong tac promoter (Ptac) facing outward at one of its ends. Expression of Ptac is under the control of the lacIq gene, also contained within the transposon. By inserting Tn5tac1 upstream from a promoterless galK gene we determined the basal level of transcription from both ends of the transposon in the absence of IPTG to be about 4% relative to the lactose promoter (Plac). As a result, derivatives of strain N100 containing these plasmids produce red colonies in MacConkey-galactose plates. Deletion of the BamHI fragment including Ptac causes galactokinase levels to drop to less than 1% of Plac, enough to render white colonies in MacConkey-galactose plates. Thus, Tn5tac1 can be used for genetic analysis under conditions in which it shows no polarity (+ IPTG), low polarity (- IPTG), or strong polarity (delta Ptac).
DNA Transposable Elements↗
Paternal phenylketonuria.
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Benzene Derivatives↗
The hha gene modulates haemolysin expression in Escherichia coli.
A mutation in the hha allele results in a large increase in the production of intracellular as well as extracellular haemolysin in Escherichia coli cells harbouring the haemolytic recombinant plasmid pANN202-312. This single gene mutation was located between 490 and 491.6 kb on the physical map of the E. coli chromosome. From the DNA sequence of hha a small polypeptide of 8629 Da was predicted and was expressed in minicells. The deduced polypeptide sequence did not show significant similarities to other characterized proteins related to the regulation of gene expression in E. coli, although it was shown that the hha mutation increases cytoplasmic synthesis of haemolysin.
Amino Acid Sequence↗
Interleukin-2 and natural killer activity in acute type B hepatitis.
Natural killer (NK) cell activity against K562 cell line, and interleukin-2 (IL-2) activity in supernatants from lectin-activated PBMC cultures from 17 patients with acute hepatitis B in the early phase of illness were studied. These patients showed enhanced NK cytotoxicity and higher levels of IL2 activity as compared with control subjects. There was a positive correlation between cytotoxicity values and levels of IL2 activity. Furthermore, in the recovery phase of illness there was a tendency towards normalization in both parameters. When patients were divided in accordance with markers of HBV replication, HBV-DNA positive patients showed increased NK cell activity and IL2 levels as compared with the control group, whereas in HBV-DNA-negative patients no differences were found. However, no differences were found between patients with HBeAg and patients with anti-HBe. These results suggest that natural cytotoxicity is increased early in the course of acute hepatitis B, while NK cell activity returns to normal later, during convalescence. Enhanced NK cell activity appears to be secondary, at least in part, to increased production of IL2. Natural cytotoxicity may be one mechanism that controls the HBV infection before other cytotoxic mechanisms become fully operative.
Acute Disease↗
Genetic elements involved in Tn21 site-specific integration, a novel mechanism for the dissemination of antibiotic resistance genes.
Transposon Tn21 codes for a site-specific integration system, which is probably a novel recombination mechanism, responsible for the acquisition of resistance genes in this widespread family of transposons. Using insertion and deletion mutagenesis we have identified the genetic loci of the various recombination hot-spots (RHS) and of the gene product (the integrase) that catalyses the reaction. The site of recombination has been localized in two of the RHSs to the DNA sequence GTTAG, which is present at the 3' termini of a loosely conserved palindromic sequence of approximately 59 bp. This 59 bp sequence, which flanks the inserted genes in a number of naturally occurring transposons, is the only element required in cis for the recombination reaction.
Base Sequence↗
The Tn21 subgroup of bacterial transposable elements.
The Tn3 family of transposable elements is probably the most successful group of mobile DNA elements in bacteria: there are many different but related members and they are widely distributed in gram-negative and gram-positive bacteria. The Tn21 subgroup of the Tn3 family contains closely related elements that provide most of the currently known variation in Tn3-like elements in gram-negative bacteria and that are largely responsible for the problem of multiple resistance to antibiotics in these organisms. This paper reviews the structure, the mechanism of transposition, the mode of acquisition of accessory genes, and the evolution of these elements.
Bacteria↗
Hypothalamic lesioned rats given haloperidol mimic the behavior of intact rats given haloperidol plus morphine.
Lateral hypothalamic (LH) damage produces rats which exhibit sensory neglect, somnolence and akinesia, while ventromedial hypothalamic (VMH) damage produces rats which exhibit sensory hyperesponsiveness (Marshall and Teitelbaum, 1977). Rats with large lesions of both LH and VMH are somnolent and akinetic but hyperesponsive to touch. When given haloperidol (5 mg/kg) the LH-VMH-damaged rats adopt an actively maintained splayed out posture, in which the limbs are abducted and extended and the body lies flat on the ground. While in this posture, reflexes of postural stability, such as buttressing against a displacing force, are partially inhibited. These postural characteristics are similar to those of normal rats given haloperidol (5 mg/kg) plus morphine (20 mg/kg) (Pellis et al., 1986).
Animals↗
Ontogeny of the endorphinergic and dopaminergic modulation on the immobility reflex elicited by clamping in rats.
The effects of some dopaminergic and endorphinergic agonists and antagonists on the immobility reflex (IR) elicited by clamping the neck of the rat were investigated. We found that both morphine and haloperidol produce a significant increase in the duration of this IR at all ages tested (10, 20 and 300 days). The effect of apomorphine depends on the age of the rat, showing an increase in the duration of the immobility reflex only at the age of 10 days which was not counteracted by haloperidol. Naloxone alone showed a slight non-significant tendency to increase the duration of the IR but blocked morphine effects at all ages tested. When naloxone was added to apomorphine there was a peculiar effect: the duration of the immobility reflex was increased significantly in rats of 20 days and adults, but not in 10-day-old rats. The combination of morphine plus haloperidol showed the most marked potentiation of the immobility reflex at all ages tested. These results are discussed with respect to the development of dopaminergic and endorphinergic systems to control posture and movement during the IR, and its possible relation to the catatonia of schizophrenics. A hypothetical model explaining an interaction between the dopaminergic and endorphinergic systems in developing and adult rats is presented.
Aging↗
General organization of the conjugal transfer genes of the IncW plasmid R388 and interactions between R388 and IncN and IncP plasmids.
The complete conjugal transfer gene region of the IncW plasmid R388 has been cloned in multicopy vector plasmids and mapped to a contiguous 14.9-kilobase segment by insertion mutagenesis. The fertility of the cloned region could still be inhibited by a coresident IncP plasmid. The transfer region has been dissected into two regions, one involved in pilus synthesis and assembly (PILW), and the other involved in conjugal DNA metabolism (MOBW). They have been separately cloned. PILW also contains the genes involved in entry exclusion. MOBW contains oriT and the gene products required for efficient mobilization by PILW. MOBW plasmids could also be mobilized efficiently by PILN, the specific pilus of the IncN plasmid pCU1, but not by PILP, the specific pilus of the IncP plasmid RP1.
Cloning, Molecular↗
Potentiation by vestibular stimulation of the immobility reflex elicited by clamping in developing and adult rats.
We have previously described (Exp. Neurol., 97: 315-326, 1987) that clamping of the neck elicits a profound immobility with flexion of limbs and ventroflexion of head and neck ('carrying posture'). We also observed that when a clamped rat pup is carried by the experimenter's hand, such carrying posture was potentiated. In the present paper we observed that in adult rats vestibular stimulation by circular acceleration potentiates the duration of immobility reflex by clamping and intensifies the limb flexion. In rat pups from 10 to 20 days, vestibular stimulation potentiated only the carrying posture but not the duration of the immobility reflex by clamping.
Age Factors↗