Analysis of developmental switching in transgenic mice with 5′ and 3′ deletions in the human β globin gene

Our interest in thecis-acting elements that promote the up-regulation of the globin gene has led to a systematic deletion analysis of portions of the globin gene in the context of the HS2 and globin gene using transgenic mice. In constructs that delete the 5 region to only 265 bp, high-level erythroid-specific expression was observed. Further deletion to 122 bp, however, results in significantly reduced expression levels A substitution of a minilocus control region for the single HS2 site was also produced, resulting in increased globin expression over that seen with the HS2 alone. These results are consistent with the presence of an enhancer-like element between –122 and –265. In addition, a construct in which the entire globin gene promoter was replaced by a thymidine kinase promoter was tested. Interestingly, no expression was detected in these transgenic mice. This may indicate the requirement for an erythroid-specific promoter to drive this gene. Finally, the 3 region of the globin gene was deleted in order to examine the effect of a previously defined 3 enhancer region. With deletion of this region, the expression of the human globin gene in transgenic mice is unchanged relative to the parental constructs.     

Homology modeling of histidine-containing phosphocarrier protein and eosinophil-derived neurotoxin: Construction of models and comparison with experiment

Homology modeling methods have been used to construct models of two proteins—the histidine-containing phosphocarrier protein (HPr) from Mycoplasma capricolum and human eosinophil-derived neurotoxin (EDN). Comparison of the models with the subsequently determined X-ray crystal structures indicates that the core regions of both proteins are reasonably well reproduced, although the template structures are closer to the X-ray structures in these regions—possible enhancements are discussed. The conformations of most of the side chains in the core of HPr are well reproduced in the modeled structure. As expected, the conformations of surface side chains in this protein differ significantly from the X-ray structure. The loop regions of EDN were incorrectly modeled—reasons for this and possible enhancements are discussed. © 1995 Wiley-Liss, Inc.     

Ultrastructural changes in major organelles during spermatial differentiation inBangia (Rhodophyta)

Summary The major organelles within the cells of maleBangia atropurpurea (Roth) C. Ag. filaments undergo a series of ultrastructural transformations during the production of spermatia. Initially, thylakoids within the large axial chloroplast develop a reticulate pattern commencing at the central pyrenoid region. Subsequent changes involve loss of lobes and diminution of volume through division; chloroplasts in final stages contain a few dilated, distorted thylakoids and many plastoglobuli. During differentiation the large nucleolus disappears from the nucleus and four masses of chromatin aggregate near the nuclear envelope. Furrows originating from the nuclear envelope form double membranes around each of the chromatin masses and most of the nucleoplasm is eliminated. Several types of fibrillar vesicles are formed during the process and large floridean starch reserves are utilized. Multilamellar bodies and microbody-like structures occur within the cells during certain phases of spermatiogenesis.     

Immunoglobulin E decapeptide-induced 5-hydroxytryptamine release from rat peritoneal mast cells. Comparison with corticotropin-(1-24)-peptide, polyarginine, polylysine and antigen.

A synthetic basic decapeptide from the C4 domain of human immunoglobulin E, corticotropin-(1-24)-peptide, polyarginine and polylysine stimulated up to 90% net release of 5-hydroxytryptamine from mast cells in rat peritoneal-cell suspensions. Concentration-response curves to all four polypeptides were parallel. Polyarginine and polylysine (EC50 congruent to 0.05 microM) were approximately 100-fold more potent than immunoglobulin E decapeptide and corticotropin-(1-24)-peptide (EC50 congruent to 5 microM). Polypeptide-induced release was complete within 5-10s. Immunoglobulin-E-decapeptide-induced 5-hydroxytryptamine release was additive to that induced by low concentrations of polyarginine, but non-additive to that induced by high concentrations of polyarginine. In contrast, release induced by antigen was additive along the whole length of the concentration-response curve to polyarginine. Benzalkonium chloride inhibited immunoglobulin-E-decapeptide- and polyarginine-induced 5-hydroxytryptamine release but enhanced release induced by immunological stimulation.     

Applications of biofeedback to the treatment of asthma: A critical review

Both muscular and respiratory biofeedback procedures have been employed in attempts to reduce symptoms of bronchial asthma. Research relating to these approaches is reviewed in the present article. Biofeedback training both for facial muscle relaxation and for respiratory resistance decrease improves short-term pulmonary function in asthmatic individuals. These forms of training represent promising avenues for the management of asthma. However, unqualified endorsement of these procedures is premature, at the present time, since their influence on asthma-related variables other than pulmonary function has not been determined and since their long-term effects have not been investigated.     

Swelling and ion uptake in cat cerebrocortical slices:

Cat cerebrocortical slices incubating in medium containing normal K+ concentrations were exposed to a number of different transmitters. Norepinephrine, histamine and adenosine or 2-chloroadenosine caused increased swelling of the slices associated with an increased Na+ and Cl- content. These effects were seen only when both Cl- and HCO3- were present in the medium, and were inhibited by a number of anion transport inhibitors. These characteristics were identical to those of the HCO3(-)-dependent component of the swelling induced by high K+ levels in the medium. Other transmitters, namely 5-hydroxytryptamine, dopamine, and gamma-amino butyric acid, were ineffective. The effects of norepinephrine, histamine and 2-chloroadenosine were antagonised by propranolol and phentolamine, chlorpheniramine and diphenhydramine, and theophylline respectively. These antagonists also inhibited HCO3(-)-dependent, K+-stimulated swelling. The transmitters which induced swelling also stimulated the carbonic anhydrase activity of cerebrocortical slices. We conclude from these data that the HCO3(-)-dependent component of K+-stimulated swelling may be due to K+-stimulated release of transmitters. Furthermore, the fact that the transmitters which induce swelling have also been reported to be most effective in increasing cAMP content in both brain slices or cultured astrocytes is consistent with the swelling response being mediated via cAMP-induced changes and being predominantly localized to astrocytes.     

Role of thrombin exosites in inhibition by heparin cofactor II.

We determined the role of specific thrombin "exosites" in the mechanism of inhibition by the plasma serine proteinase inhibitors heparin cofactor II (HC) and antithrombin (AT) in the absence and presence of a glycosaminoglycan by comparing the inhibition of alpha-thrombin to epsilon- and gamma T-thrombin (produced by partial proteolysis of alpha-thrombin by elastase and trypsin, respectively). All of the thrombin derivatives were inhibited in a similar manner by AT, either in the absence or presence of heparin, which confirmed the integrity of both heparin binding abilities and serpin reactivities of epsilon- and gamma T-thrombin compared to alpha-thrombin. Antithrombin activities of HC in the absence of a glycosaminoglycan with alpha-, epsilon, and gamma T-thrombin were similar with rate constants of 3.5, 2.4, and 1.2 x 10(4) M-1 min-1, respectively. Interestingly, in the presence of glycosaminoglycans the maximal inhibition rate constants by HC with heparin and dermatan sulfate, respectively, were as follows: 30.0 x 10(7) and 60.5 x 10(7) for alpha-thrombin, 14.6 x 10(7) and 24.3 x 10(7) for epsilon-thrombin, and 0.017 x 10(7) and 0.034 x 10(7) M-1 min-1 for gamma T-thrombin. A hirudin carboxyl-terminal peptide, which binds to anion-binding exosite-I of alpha-thrombin, dramatically reduced alpha-thrombin inhibition by HC in the presence of heparin but not in its absence. We analyzed our results in relation to the recently determined x-ray structure of D-Phe-Pro-Arg-chloromethyl ketone-alpha-thrombin (Bode, W., Mayr, I., Baumann, U., Huber, R., Stone, S. R., and Hofsteenge, J. (1989) EMBO J. 8, 3467-3475). Our results suggest that the beta-loop region of anion-binding exosite-I in alpha-thrombin, which is not present in gamma T-thrombin, is essential for the rapid inhibition reaction by HC in the presence of a glycosaminoglycan. Therefore, alpha-thrombin and its derivatives would be recognized and inhibited differently by HC and AT in the presence of a glycosaminoglycan.     

Chaos game representation of coding regions of human globin genes and alcohol dehydrogenase genes of phylogenetically divergent species

Summary Chaos game representation (CGR) is a novel holistic approach that provides a visual image of a DNA sequence quite different from the traditional linear arrangement of nucleotides. Although it is known that CGR patterns depict base composition and sequentiality, the biological significance of the specific features of each pattern is not understood. To systematically examine these features, we have examined the coding sequences of 7 human globin genes and 29 relatively conserved alcohol dehydrogenase (Adh) genes from phylogenetically divergent species. The CGRs of human globin cDNAs were similar to one another and to the entire human globin gene complex. Interestingly, human globin CGRs were also strikingly similar to human Adh CGRs. Adh CGRs were similar for genes of the same or closely related species but were different for relatively conserved Adh genes from distantly related species. Dinucleotide frequencies may account for the self-similar pattern that is characteristic of vertebrate CGRs and the genome-specific features of CGR patterns. Mutational frequencies of dinucleotides may vary among genome types. The special features of CG dinucleotides of vertebrates represent such an example. The CGR patterns examined thus far suggest that the evolution of a gene and its coding sequence should not be examined in isolation. Consideration should be given to genome-specific differential mutation rates for different dinucleotides or specific oligonucleotides. Offprint requests to: S. M. Singh     

New and noteworthy species in Begonia section Gireoudia (Begoniaceae) from Mexico

Two new species are described inBegonia sectionGireoudia:B. rafael-torresii andB. mariti.Begonia karwinskyana, known previously only from its type, is described more amply and discussed.