Plant regeneration in vitro of South Pacific taro (Colocasia esculenta var. esculenta cv. Akalomamale,Aracea)

Summary Axillary bud expiants from South Pacific (Solomon Islands) taro, Colocasia esculenta var. esculenta cv. Akalomamale (Araceae) cultured on a modified Murashige-Skoog medium containing 1 mg NAA 1^–1 and TE formed callus and produced multiple plantlets. Explants died if NAA was present at levels lower than 0.1 mg 1^–1. BA was not required and may have been inhibitory. Plantlets developed faster and became larger following transfer to a hormone-free medium two weeks after the start of culture. Fully grown plants were established in a potting mix and are growing well in a greenhouse.Abbreviations BA benzyladenine - BM basal medium - Ca Colocasia esculenta var. antiquorum - Ce Colocasia esculenta var. esculenta - Ck cytokinin(s) - CW coconut water - HSMSM half strength Murashige Skoog macroelements - HSMS half strength Murashige and Skoog medium - IM initial medium(ia) - MS Murashige and Skoog medium - NAA naphthaleneacetic acid - SM second medium - TE taro corm extract - UCI University of California, Irvine     

Purification and properties of theDrosophila zen protein

Summary The zen protein is encoded by the zerknullt gene required for normal early development inDrosophila. Like many regulatory proteins of this type, zen contains a 60 amino acid homeobox sequence. We have purified the zen protein and studied its solution behavior and its interaction with DNA. The zen protein exists as a monomer in solution with a molecular weight of about 40000. It binds specifically to a site about 900 bases upstream from thezen gene. Within this binding site DNase protection experiments indicate that binding is confined to two regions approximately 11 and 14 bases in length that are separated by about 30 base pairs. The protein concentration dependence of the binding curve suggests that protein binding is non cooperative.     

Regulation of cardiac sarcoplasmic reticulum (Ca2+ + Mg2+)-ATPase

Summary The two high affinity calcium binding sites of the cardiac (Ca²⁺ + Mg²⁺)-ATPase have been identified with the use of Eu³⁺. Eu³⁺ competes for the two high affinity calcium sites on the enzyme. With the use of laser-pulsed fluorescent spectroscopy, the environment of the two sites appear to be heterogeneous and contain different numbers of H₂O molecules coordinated to the ion. The ion appears to be occluded even further in the presence of ATP. Using non-radiative energy transfer studies, we were able to estimate the distance between the two Ca²⁺ sites to be between 9.4 to 10.2 A in the presence of ATP. Finally, from the assumption that the calcium site must contain four carboxylic side chains to provide the 6–8 ligands needed to coordinate calcium, and based on our recently published data, we predict the peptidic backbone of the two sites.     

Protein synthesis rates in rat brain regions and subcellular fractions during aging

In vivo protein synthesis rates in various brain regions (cerebral cortex, cerebellum, hippocampus, hypothalamus, and striatum) of 4-, 12-, and 24-month-old rats were examined after injection of a flooding dose of labeled valine. The incorporation of labeled valine into proteins of mitochondrial, microsomal, and cytosolic fractions from cerebral cortex and cerebellum was also measured. At all ages examined, the incorporation rate was 0.5% per hour in cerebral cortex, cerebellum, hippocampus, and hypothalamus and 0.4% per hour in striatum. Of the subcellular fractions examined, the microsomal proteins were synthesized at the highest rate, followed by cytosolic and mitochondrial proteins. The results obtained indicate that the average synthesis rate of proteins in the various brain regions and subcellular fractions examined is fairly constant and is not significantly altered in the 4 to 24-month period of life of rats.A preliminary report of these results was previously presented at: WFN-ESN Joint Meeting on: Cerebral Metabolism in Aging and Neurological Disorders, Baden, August 28–31, 1986.     

Modulation of xanthine dehydrogenase and oxidase activities during the hormonal induction of vaginal epithelial differentiation in ovariectomized mice

In situ hybridization and immunocytochemical techniques have been used to examine the distribution of vitamin-D-induced calbindin mRNA and calbindin protein in enterocytes lining the crypts and villi of chicken small intestine. Basal villus enterocytes contained approximately twice as much calbindin but over three times as much calbindin mRNA compared to values found in basal crypt and upper villus enterocytes, all values being measured 2 days after vitamin D injection into D-deficient chickens. Virtually no calbindin mRNA was detected in tissues taken from control D-deficient birds. Direct proportionality found between calbindin mRNA and calbindin content in enterocytes of basal crypt, mid and upper villus suggests pre-translational control over calbindin synthesis. The implications of possible inefficient translation of calbindin mRNA in basal villus enterocytes are discussed. Present methods of analysis provide a novel way to study mechanisms controlling gene expression throughout the whole process of enterocyte differentiation.     

Determination of the origin of nondisjunction in a 49,XXXXY male using hypervariable dinucleotide repeat sequences

Summary We present a patient with a 49,XXXXY chromosome constitution in whom the origin of the extra X chromosomes was determined by analysis of five polymorphic CA (or GT) dinucleotide repeat sequences. This class of DNA marker has recently been demonstrated to be hypervariable with heterozygosity values up to 80%. By polymerase chain reaction (PCR) analysis of the dinucleotide repeat length polymorphisms, we have shown that all four X chromosomes were of maternal origin.     

Detection of major genes for susceptibility to leprosy and its subtypes in a Caribbean island: Desirade island.

To determine the nature of the genetic component controlling susceptibility to leprosy and its subtypes, complex segregation analysis, by means of the POINTER strategy, was performed on 27 multigenerational pedigrees from Desirade, a Caribbean island where leprosy is highly prevalent. The results are consistent with the presence of a recessive or codominant major gene controlling susceptibility to leprosy per se and nonlepromatous leprosy, respectively. Under the major-gene model, tests of homogeneity to check for internal consistency of the sample and to compare subsamples according to an epidemiological criterion, the place of residence of the probands, were conducted; results of none of these tests were significant. However, we have noted that information on 3 generations (nuclear families with a pointer to the sibship) is of major importance for detecting major gene(s). Besides, the discrepancy in the results obtained in separate analyses of the family subsamples defined by the place of residence of the probands is discussed in terms of possible genetic and/or environmental differences. Referring to experimental data and previous studies, we suggest that the gene for susceptibility to leprosy per se and that for susceptibility to nonlepromatous leprosy might be different, acting at successive stages of the immune response to infection with Mycobacterium leprae.