Carrier-Mediated Uptake of Abscisic Acid by Suspension-Cultured Amaranthus tricolor Cells

Abscisic acid (ABA) uptake by Amaranthus tricolor cell suspensions was found to include both a nonsaturable component and a saturable part with K_m of 3.74 ± 0.43 micromolar and an apparent V_max of 1.5 ± 0.12 nanomoles per gram per minute. These kinetic parameters as well as the uptake by intact cells at 0°C or by frozen and thawed cells, are consistent with operation of a saturable carrier. This carrier-mediated ABA uptake was partially energized by ΔpH: it increased as the external pH was lowered to pH 4.0; it decreased after the lowering of the ΔpH by the proton ionophore carbonylcyanide-m-chlorophenylhydrazone or after the altering of metabolically maintained pH gradient by metabolic inhibitors (KCN, oligomycin). The carrier is specific for ABA among the plant growth regulators tested, is unaffected by (RS)-trans-ABA and was inhibited by (S)-ABA, (R)-ABA, and also by the ABA analog LAB 173711.     

The candidate gene for the X-linked Kallmann syndrome encodes a protein related to adhesion molecules

Kallmann syndrome associates hypogonadotropic hypogonadism and anosmia and is probably due to a defect in the embryonic migration of olfactory and GnRH-synthesizing neurons. The Kallmann gene had been localized to Xp22.3. In this study 67 kb of genomic DNA, corresponding to a deletion interval containing at least part of the Kallmann gene, were sequenced. Two candidate exons, identified by multiparameter computer programs, were found in a cDNA encoding a protein of 679 amino acids. This candidate gene (ADMLX) is interrupted in its 3' coding region in the Kallmann patient, in which the proximal end of the KAL deletion interval was previously defined. A 5' end deletion was detected in another Kallmann patient. The predicted protein sequence shows homologies with the fibronectin type III repeat. ADMLX thus encodes a putative adhesion molecule, consistent with the defect of embryonic neuronal migration.     

Distribution pattern of decapod larvae off the north-western Iberian Peninsula coast (NE Atlantic)

In October 1977 the model of general circulation of the watermasses off the coast of Galicia, and the presence of a coastalupwelling, led to a high primary productivity. This high productivityin turn favoured the development of a rich population of decapodlarvae. The abundance and distribution pattern of these organismswere closely linked (i) to the abundant presence of the correspondingadult species in the area, (ii) with the spatial distributionof phytoplanktonic populations concurrently studied by Estrada[J. Plankton Res ., 6, 417–434 (1984)] and (iii) withthe hydrodynamic pattern in the area. Fifty-two decapod larvaetaxa were identified and Solenocera membranacea, Pisidia longicornis,Pilumnushirtellus and Goneplax rhomboides were the most representativespecies It was observed that the greatest concentrations oflarvae (3387 larvae 10^–2 m^–3) were to be found nearthe mouth of the Rfas Baixas (situated in the south-west ofthe coastal area) and in some zones further out to sea (863larvae 10^–2 m^–3) (due to a process of hydrodynamictransport)     

Mapping of the structural gene for S-adenosyl homocysteine hydrolase to mouse Chromosome 2, and related sequences to Chromosomes 8 and X

Comparative mapping studies in human and mouse have shown that, to date, human Chromosome (Chr) 20 is completely syntenic with distal mouse Chr 2. The structural locus for S-adenosyl-l-homocysteine hydrolase (EC 3.3.1.1) in human, AHCY, maps to 20 qterq13.1, and we report here that the homologous locus in the mouse, Ahcy, maps to distal mouse Chr 2 with gene order Pcna-Ahcy-Ada. Analysis of 123 progeny of an interspecific backcross between a laboratory stock, AN, and Mus spretus using a rat cDNA probe revealed the presence of at least two other Ahcy-related sequences segregating independently in the mouse genome. One, Ahcy-rs1, was mapped to Chr 8 in the BXH recombinant inbred strains, and the other, Ahcy-rs2, shows a pattern of inheritance consistent with X-linkage.     

The spo0A gene is implicated in the maintenance of non-complementing diploids in Bacillus subtilis

Bacillus subtilis can exist in a diploid state in which two genetically distinct chromosomes co-exist in the same cell and yet only one of them is expressed, thereby determining the phenotype. Such cells are called non-complementing diploids (Ncds). In this study, two types of experiments are reported which indicate that a previously known pleiotropic gene, spo0A, plays a role in the maintaining the diploid state, as follows. (i) When protoplasts of two Spo0A mutant strains were fused, the resulting products continued to segregate cells of both parental phenotypes for many more divisions than had been reported previously. (ii) When a stable Ncd (an Ncd in which the unexpressed markers are not spontaneously activated at a detectable level) harbouring a chloramphenicol acetyltransferase gene on the silent chromosome was transformed with spo0A null alleles the transformants often expressed chloramphenicol acetyltransferase activity. Together these results indicate that the spo0A gene is involved in maintenance of the diploid state in both unstable and stable Ncds.     

5′-Nucleotidase in spinal meningeal compartments in the rat

Summary The distribution of 5-nucleotidase (5-Nu) is reported in spinal meninges of the rat on the basis of an immunohistochemical and enzyme histochemical investigation. Strong immunoreactivity was found in the arachnoid membrane and in the sheaths of the spinal roots as well as in septa subdividing the roots. Also the superficial layer of the ligamentum denticulatum showed enzyme staining. No immunoreactivity could be detected in the pia mater or along the spinal nerve roots outside the subarachnoid space. Within the arachnoid mater the immunoreactivity was concentrated in the basal zone of the arachnoid membrane, thus appearing as a narrow fluorescent band near the border of the dura. An accentuation of immunoreactivity could be observed in areas where small dural blood vessels approach the subarachnoid space. It is well known that adenine nucleotides released from neural and glial cells of the central nervous system finally reach the cerebrospinal fluid. We presume that 5-Nu in the arachnoid membrane and spinal root sheaths is responsible for the conversion of adenine nucleotides into adenosine and that this conversion is associated with the reabsorption process of cerebrospinal fluid which most probably also takes place in spinal meninges. Adenosine, the product of 5-nucleotidase, could play a role in the reabsorption process by its vasodilatatory effect on dural and epidural vessels.     

Does alternative exon usage contribute to serotonin receptor heterogeneity?

We have previously isolated serotonin 5-HT_1C receptor cDNA clones. In contrast to most other receptors coupled to GTP binding proteins, the 5-HT_1C receptor gene contains several introns in its coding region. A similar exon-intron distribution is found in the 5-HT₂ receptor gene. The presence of large introns tempted us to test whether exchange of exons contributes to serotonin receptor heterogeneity. Therefore, blots with RNAs from different regions of the brain and brain slices were hybridized in situ with probes representing individual exons. We did not find any evidence for the exchange of exons which should result in an unequal distribution of hybridization signals found with the exon-specific probes. With the methodology used we should be able to see differential splicing in the form where individual exons are used alternatively resulting in mRNAs coding for different serotonin receptor types. We would not, however, see if a given exon can be modified by the alternative use of several splice-junctions.