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Query: UNIPROT:P06889 (Mol)
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Volume measurements were performed on intact bull and mouse sperm heads and amembranous sperm nuclei, both in the fully hydrated (fluid cell) and dehydrated (air-dried on glass coverslips) states by atomic force microscopy (AFM). Data were obtained by analyzing a small population of cells/nuclei, as well as by performing repeated measurements on single cells imaged following the addition of increasing concentrations of propanol. Results show that the volume of fully hydrated, intact sperm heads and amembranous sperm chromatin particles are at least twice the volume of their air-dried counterparts. Dehydration occurs rapidly in air, and the reduction in volume of chromatin induced by water loss appears to be completely reversible. These studies demonstrate that both mouse and bull sperm chromatin are extensively hydrated in the native state, and are not as compact as previous studies have suggested.
Mol Reprod Dev 1996 Sep
PMID:Extent of sperm chromatin hydration determined by atomic force microscopy. 887 74

A cDNA and two genomic clones comprising highly similar genes that encode a protein with a Myb-related DNA-binding domain were isolated from the resurrection plant Craterostigma plantagineum. The structure of cpm5 and cpm10 (Craterostigma plantagineum myb) genes consists of three putative exons encoding a protein of 36.6 kDa. The cDNA of cpm7 encodes a closely related protein of 36.8 kDa. The canonical Myb domain present in transcriptional activators of yeast, animals and plants was localized in the amino terminus of deduced Cpm5, Cpm7 and Cpm10 proteins and corresponds to the two Myb repeats found in plants. The Myb domain of Cpm deduced proteins and a short stretch of amino acids adjacent to this region are closely related to a myb gene from Arabidopsis thaliana which is expressed in response to osmotic stress and ABA. The rest of the deduced protein has no similarity to other reported sequences. The myb-related genes in the Craterostigma genome comprise a small gene family of 6-8 members as estimated by hybridization with a bona fide Myb domain probe. Northern blot experiments showed specific expression of cpm10 in undifferentiated callus tissue up-modulated by ABA and expression of cpm7 mRNA in roots up-regulated by dehydration.
Plant Mol Biol 1996 Nov
PMID:A family of novel myb-related genes from the resurrection plant Craterostigma plantagineum are specifically expressed in callus and roots in response to ABA or desiccation. 898 May 22

Plants generally accumulate free proline under osmotic stress conditions. Upon removal of the osmotic stress, the proline levels return to normal. In order to understand the mechanisms involved in regulating the levels of proline, we cloned and characterized a proline dehydrogenase (PDH) cDNA from Arabidopsis thaliana (AtPDH). The 1745 bp cDNA contains a major open reading frame encoding a peptide of 499 amino acids. The deduced amino acid sequence has high homology with both Saccharomyces cerevisiae and Drosophila melanogaster proline oxidases and contains a putative mitochondrial targeting sequence. When expressed in yeast, the AtPDH cDNA complemented a yeast put1 mutation and exhibited proline oxidase activity. We also determined the free proline contents and the delta 1-pyrroline-5-carboxylate synthetase (P5CS) and PDH mRNA levels under different osmotic stress and recovery conditions. The results demonstrated that the removal of free proline during the recovery from salinity or dehydration stress involves an induction of the PDH gene while the activity of P5CS declines. The reciprocal regulation of P5CS and PDH genes appears to be a key mechanism in the control of the levels of proline during and after osmotic stress. The PDH gene was also significantly induced by exogenously applied proline. The induction of PDH by proline, however, was inhibited by salt stress.
Mol Gen Genet 1996 Dec 13
PMID:Reciprocal regulation of delta 1-pyrroline-5-carboxylate synthetase and proline dehydrogenase genes controls proline levels during and after osmotic stress in plants. 900 20

Recent studies indicate that calcium binding proteins may play a role in determining the electrical firing patterns of the hypothalamic magnocellular oxytocin (OT) and vasopressin (VP) neurons. In this study we have examined the calbindin-D28k mRNA content of magnocellular neurons in the supraoptic (SON) and paraventricular (PVN) nuclei and determined whether changes in expression correlate with the specific patterns of electrical activity displayed by these cells under different physiological circumstances. In situ hybridization with [35S]-labelled oligonucleotides revealed a heterogeneous pattern of calbindin-D28k mRNA expression in the SON and magnocellular PVN. Quantitative analysis demonstrated that the number of silver grains/cell in the dorsal half of the SON was approximately 30% higher (P < 0.05) than that of the ventral half of the nucleus. Within the PVN, calbindin-D28k mRNA-expressing neurons were detected in the medial magnocellular division of the PVN but not in magnocellular cells forming the core of the lateral magnocellular division. Dehydration for 24 h did not alter calbindin-D28k mRNA expression in the SON, PVN or cingulate cortex. In parturient and lactating rats, calbindin-D28k mRNA levels were significantly (P < 0.05) reduced in the medial magnocellular division of the PVN compared with virgin animals. No significant differences in calbindin-D28k mRNA expression were observed in either ventral or dorsal halves of the SON, or in the cingulate cortex of these animals. These results provide evidence for the differential expression of calbindin-D28k mRNA by hypothalamic magnocellular neurons and suggest that OT cells may express more calbindin-D28k mRNA than VP neurons. The reduction in calbindin-D28k mRNA expression by putative OT neurons of the PVN at the time of parturition and lactation supports the hypothesis of Li and colleagues (J. Physiol., 488 (1995) 601-608) that calbindin may play a part in determining the electrical firing patterns of magnocellular neurons. However, the absence of any similar decrease in the SON suggests that changes in calbindin-D28k mRNA expression are not essential for OT neurons to exhibit episodic bursting behavior.
Brain Res Mol Brain Res 1996 Dec
PMID:Calbindin-D28k mRNA expression in magnocellular hypothalamic neurons of female rats during parturition, lactation and following dehydration. 901 84

Haloperidol (HP) and its tetrahydropyridine dehydration product 4-(4-chlorophenyl)-[4-(fluorophenyl)-4-oxobutyl]-1,2,3,6-tetrahydropyrid ine (HPTP) are both metabolized in vivo to several pyridinium metabolites with potential neurotoxic properties similar to the neurotoxin 1-methyl-4-phenylpyridinium (MPP+), a metabolite of the parkinsonian-inducing agent 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The effect of long-term HPTP treatment on the central nervous system of baboons (Papio ursinus) was studied using [123I]iodobenzamide (IBZM) and single photon emission computed tomography (SPECT) at 1-14 weeks after termination of HPTP treatment. Striatal dopamine receptor binding was measured semiquantitatively by calculating the IBZM count rate ratios of the basal ganglia to frontal cortex and basal ganglia to cerebellum. Relative striatal perfusion was assessed by similar 99mTc-HMPAO (hexamethylpropylene amine oxime) ratios. Time activity curves of IBZM from the brain structures suggest that HPTP treatment results in a marked reduction in central dopamine ligand binding, and in particular D2-like receptor binding. Increased washout of the ligand from all the brain structures investigated was seen in the HPTP-treated animals, also consistent with reduced binding. Cerebral blood flow in the control and HPTP-treated groups was similar, indicating that this did not account for the reduced dopamine receptor binding of the IBZM ligand. These data suggest that treatment with HPTP induces significant effects on dopamine receptor binding that may contribute to some of the neurological disorders observed in humans undergoing chronic HP treatment.
Brain Res Mol Brain Res 1996 Dec 31
PMID:Long-term treatment with the tetrahydropyridine analog (HPTP) of haloperidol influences dopamine ligand binding in baboon brain. An [123I]iodobenzamide (IBZM) SPECT study. 903 40

A cDNA for delta1-pyrroline-5-carboxylate (P5C) synthetase (cOsP5CS), an enzyme involved in the biosynthesis of proline, was isolated and characterized from a cDNA library prepared from 14-day-old seedlings of Oryza sativa cv. Akibare. The deduced amino acid sequence of the P5CS protein (OsP5CS) from O. sativa exhibited 74.2% and 75.5% homology to that of the P5CS from Arabidopsis thaliana and Vigna aconitifolia, respectively. Northern blot analysis revealed that the gene for P5CS (OsP5CS) was induced by high salt, dehydration, treatment of ABA and cold treatment, while it was not induced by heat treatment. Simultaneously, accumulation of proline was observed as a result of high salt treatment in O. sativa. Moreover, the levels of expression of OsP5CS mRNA and content of proline under salt stress condition were compared between a salt-tolerant cultivar, Dee-gee-woo-gen (DGWG) and a salt-sensitive breeding line, IR28. It was observed that the expression of the P5CS gene and the accumulation of proline in DGWG steadily increased, whereas those in IR28 increased slightly.
Plant Mol Biol 1997 Mar
PMID:Characterization of the gene for delta1-pyrroline-5-carboxylate synthetase and correlation between the expression of the gene and salt tolerance in Oryza sativa L. 910 9

We have identified a new wheat PKABA1-like protein kinase gene, TaPK3, that is expressed in greening wheat seedlings. TaPK3 has high sequence homology (97% similarity with some sequence diversity at the 3' end) to the wheat PKABA1 protein kinase mRNA, which is upregulated by cold-temperature treatment, dehydration and abscisic acid (ABA). Use of a TaPK3 gene-specific probe has revealed that TaPK3 is differentially expressed with respect to PKABA1. TaPK3 mRNA accumulates in greening shoot tissue of wheat, but is not affected by dehydration, cold-temperature treatment or ABA. Based on sequence and expression differences, we conclude that expression of the PKABA1-like protein kinases is not limited to stress responses.
Plant Mol Biol 1997 Mar
PMID:The wheat protein kinase gene, TaPK3, of the PKABA1 subfamily is differentially regulated in greening wheat seedlings. 910 17

Small proteinaceous infectious particles called prions cause certain neurodegenerative diseases in human and animals. Limited proteolysis of infectious scrapie prions PrP(Sc) yields an N-truncated polypeptide termed PrP 27-30, which encompasses residues 90 to 231 of PrP(Sc) and which assembles into 100 to 200 A wide amyloid rods. It has been hypothesized that the infectious prion is converted from its non-infectious cellular form (PrP(C)) by means of an alpha-helical to beta-sheet conformational change. Secondary structure analysis, computer modeling, and structural biophysics methods support this hypothesis. Residues 90 to 145 of PrP, which contain two putative alpha-helical domains H1 and H2, may be of particular relevance to the disease pathogenesis, as C-terminal truncation at residue 145 was found in a patient with an inherited prion disease. Moreover, our recent X-ray diffraction analysis suggests that the peptide consisting of these residues (designated SHa 90-145) closely models the amyloidogenic beta-sheet core of PrP. In the current study, we have analyzed in detail the X-ray diffraction patterns of SHa 90-145. Two samples were examined: one that was dehydrated under ambient conditions whilst in an external magnetic field (to induce fibril orientation), and another that was sealed after partial drying. The dried, magnetically oriented sample showed a cross-beta diffraction pattern in which the fiber axis (rotation axis) was parallel to the H-bonding direction of the beta-sheets. The major wide-angle peaks indicate the presence of approximately 40 A wide beta-crystallites, which constitute the protofilament. Each crystallite is composed of several orthogonal unit cells, normal to the fiber (a-axis) direction, having lattice constants a = 9.69 A, b = 6.54 A, and c = 18.06 A. Electron density maps were calculated by iterative Fourier synthesis using beta-silk as an initial phase model. The distribution of density indicated that there were two types of beta-sheet, suggesting that larger and smaller side-chains localized to different sheets. This would arise from folding of the polypeptide in which there are turns in the middle of both the H1 and H2 domains. A monoclinic macrolattice, with a = 9.61 A, b = c = 52.99 A and alpha = 114.6 degrees, was found to index all the reflections, including those in the low-angle region. This suggests that the beta-crystallites are nearly hexagonally packed. To account for the approximately 100 A wide fibers visualized by negative staining in the electron microscope, the beta-crystallites would be arranged in 4-mers. The partially dried sample showed a sharp 4.7 A reflection (from H-bonding) and five broad peaks superimposed on monotonically decreasing diffuse scattering. This solution-like scattering was modeled by an anisometric rectangle with a thickness comparable to a singe beta-chain. The structure, which occurred during dehydration, could be a transient in the alpha-helical to beta-sheet conversion, suggesting that formation of hydrogen bonding precedes the inter-sheet interaction and assembly into the amyloid of scrapie prion.
J Mol Biol 1997 May 02
PMID:X-ray diffraction analysis of scrapie prion: intermediate and folded structures in a peptide containing two putative alpha-helices. 915 77

A cDNA encoding a phosphoinositide-specific phospholipase C (PI-PLC) from the higher plant Arabidopsis thaliana was cloned and characterized. The gene corresponding to this cDNA is designated AtPLC2. The overall structure of the predicted AtPLC2 protein is similar to those of plant PI-PLCs and mammalian delta-type PI-PLCs. Northern blot analysis revealed that AtPLC2 is expressed constitutively whereas AtPLC1S, another gene for PI-PLC of Arabidopsis, is induced by environmental stresses such as dehydration and salinity, indicating that the function of AtPLC2 is distinct from that of AtPLC1S. The AtPLC2 mRNA was detected in vegetative and floral tissues. We determined the positions of these two PI-PLCs genes on Arabidopsis chromosomes by RFLP mapping using P1 genomic clones.
Plant Mol Biol 1997 May
PMID:AtPLC2, a gene encoding phosphoinositide-specific phospholipase C, is constitutively expressed in vegetative and floral tissues in Arabidopsis thaliana. 917 24

The low-temperature (2 degrees C)-specific wheat cDNA, pTACR7, represents a gene designated tacr7 from hard red winter wheat (HRWW; Triticum aestivum L. cv. Winoka). The term low-temperature-specific (LTS) is used because tacr7 is not induced by ABA or stresses such as salt, dehydration, and heat. pTACR7 was isolated by RT-PCR with mRNA from wheat crown tissue, the oligonucleotide primers derived from the barley cognate pHVCR8 (GenBank accession number L28091). Based on the deduced amino acid sequence, TACR7 is highly hydrophobic, with a single transmembrane domain and an amino acid bias for leucine (19%). Thus, the encoded protein TACR7 is unique among low-temperature-regulated wheat proteins described in the literature. Analysis of steady-state levels of tacr7 transcripts (630 nt) showed accumulation in wheat seedlings, crown tissue, and callus cultures after transfer from control (25 degrees C) to low temperature (2 degrees C). No detectable transcripts were observed by northern blot hybridization with pTACR7 probe from seedling or callus treated with ABA, salt, dehydration, or heat stress. tacr7 transcripts accumulated during 2 degrees C exposure to a greater amount in a freeze-resistant HRWW (FR; SDmut 16029) than in a freeze-susceptible HRWW (FS; SDmut 16169) crown tissue, with the largest difference between genotypes being 30% +/- 3% at 3 weeks.
Plant Mol Biol 1997 Jul
PMID:cDNA structure and expression patterns of a low-temperature-specific wheat gene tacr7. 924 45


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