Immunogold Localisation of the Intermediate Chain within the Protein Complex of Cytoplasmic Dynein

It was our goal to determine the location of the intermediate chain within the complex of cytoplasmic dynein by immunoelectron microscopy. To do so we generated two monoclonal antibodies (m74-1 and m74-2) specific for the intermediate chain. Both antibodies recognised the intermediate chain by sodium dodecyl sulphate–polyacrylamide gel electrophoresis immunoblot and ELISA assays of native and denatured proteins. When sucrose density gradient-purified cytoplasmic dynein from bovine brain was incubated with the gold-conjugated monoclonal antibodies, m74-1 and m74-2, and examined by negative staining, the gold label was found opposite the globular heads at the base of the V-shaped stalk of the motor complex. The labelling of the intermediate chain is the first mapping of a component within cytoplasmic dynein. The identification of the intermediate chain at the base of the complex supports a possible docking function of the intermediate chain.     

SEQUENCES OF THE RRN18 GENES OF CHLAMYDOMONAS HUMICOLA AND C. DYSOSMOS ARE IDENTICAL,IN AGREEMENT WITH THEIR COMBINATION IN THE SPECIES C. APPLANATA (CHLOROPHYTA)1

The nuclear Rrn18 gene coding for small-subunit ribosomal RNA was amplified from Chlamydomonas humicola and C. dysosmos. The sequences were identical, in agreement with the combination of these two species under the name C. applanata on morphological and physiological grounds by Ettl and Schlösser (1992).     

Polarity of meiotic gene conversion is 5′ to 3′ within the niaD gene of Aspergillus nidulans

We have examined polarity of meiotic gene conversion in the niiA-niaD gene cluster of Aspergillus nidulans in two-point crosses. The type and position of the mutations represented by the niaD alleles and the correlation between the relative frequency of gene conversion and the physical position of these mutations were determined. We show that polarity of meiotic gene conversion is 5 to 3 (transcribed strand) within the niaD gene. Additional crosses involving a niiA allele and a niaD allele show little polarity of gene conversion, which suggests that the recombination events leading to restoration of the niaD gene are initiated upstream of the coding region of the niaD gene but within the niiA-niaD gene cluster, possibly within the intergenic promoter region.     

Factors controlling the growth of field populations of Hydrodictyon reticulatum in New Zealand

Since Hydrodictyon reticulatum was introduced to New Zealand it has spread rapidly and produced persistent annual nuisance growths in areas where nuisance algal had not occurred previously. Field bioassays were conducted at 10 sites between August 1993 and February 1995 to evaluate the seasonal growth patterns and the factors controlling growth under natural conditions. H. reticulatum exhibited a strong seasonal growth pattern with growth rates up to 0.33 doublings d^-1 from August to March, are duction in growth rate in April and little or no growth from May to July. The H. reticulatum present in New Zealand has are latively low requirement for dissolved inorganic nitrogen (DIN) in comparison with other nuisance species, with its growth rate being saturated at 200 mg m^-3. This and the high affinity for DIN as shown by a K_s of 29 mg m^-3 have been key factors in the establishment of nuisance growths of H. reticulatum in New Zealand. This revised version was published online in August 2006 with corrections to the Cover Date.     

Clinical and Molecular Characterization of Patients with Distal 11q Deletions

Jacobsen syndrome is caused by segmental aneusomy for the distal end of the long arm of chromosome 11. Typical features include mild to moderate psychomotor retardation, trigonocephaly, facial dysmorphism, cardiac defects, and thrombocytopenia, though none of these features are invariably present. To define the critical regions responsible for these abnormalities, we studied 17 individuals with de novo terminal deletions of 11q. The patients were characterized in a loss-of-heterozygosity analysis using polymorphic dinucleotide repeats. The breakpoints in the complete two-generation families were localized with an average resolution of 3.9 cM. Eight patients with the largest deletions extending from 11q23.3 to 11qter have breakpoints, between D11S924 and D11S1341. This cytogenetic region accounts for the majority of 11q⁻ patients and may be related to the FRA11B fragile site in 11q23.3. One patient with a small terminal deletion distal to D11S1351 had facial dysmorphism, cardiac defects, and thrombocytopenia, suggesting that the genes responsible for these features may lie distal to D11S1351. Twelve of 15 patients with deletion breakpoints as far distal as D11S1345 had trigonocephaly, while patients with deletions distal to D11S912 did not, suggesting that, if hemizygosity for a single gene is responsible for this dysmorphic feature, the gene may lie distal to D11S1345 and proximal to D11S912.     

Phosphinothricin stimulates somatic embryogenesis in grape (Vitis sp. L.)

The effect of phosphinothricin concentration on embryo production from an embryogenic callus of Chancellor (Vitis L. complex interspecific hybrid) was tested. Embryogenic callus was cultured on medium supplemented with nine phosphinothricin concentrations (0, 0.1, 0.5, 1, 1.5, 2, 3, 5, and 10 mg/l). The highest number of embryos per plate was observed at 0.5 mg/l phosphinothricin. The use of phosphinothricin to stimulate embryo production did not affect embryo germination and plantlet formation. Three germination techniques were compared. Embryo dehydration or growth on Transfergelsolidified medium gave higher germination rates than chilling treatments. Most germinated somatic embryos produced secondary embryos from the hypocotyl after a few weeks of culture. Regardless of the germination technique, the plantlet conversion rate was very low.Abbreviations AC activated charcoal - 2,4-D 2,4-dichlorophenoxyacetic acid - BA 6-benzylaminopurine - MS Murashige and Skoog (1962) basal medium - NN Nitsch and Nitsch (1969) medium - PPT phosphinothricin     

Identification of tomato bushy stunt virus in cherry and plum trees showing fruit pitting symptoms

The fruit pitting symptoms on cherries, plums and prunes were investigated from the standpoint of their etiology. Tomato bushy stunt virus (TBSV) was isolated from pitted fruits of these plants and from their leaves and identified by means of biological and serological methods. Both isolates reacted with antisera againstPetunia and artichoke strain of this virus. In addition, the etiology of pseudopox disease of plum and that of cherry detrimental canker is discussed.     

Purification and properties of arabis mosaic and tomato bushy stunt viruses isolated from lilac (Syringa vulgaris L.)

The paper gives more detailed characteristics of Arabis mosaic virus (AMV) and tomato bushy stunt virus (TBSV) isolated from lilac, the latter being identified in lilac (from plants suffering from yellow ring disease) for the first time. The isolate of TBSV from lilac, from which an antiserum with a titre of 1024 was prepared, is closely related to the artichoke strain. Information is given about two types of ringspot disease and about chlorotic ringspot of lilac. Whereas in the leaves of lilac suffering from ringspot disease (of ring mosaic type) the presence of AMV was demonstrated, the sap transmission from the leaves diseased with ringspot of linepattern (and wave-like mosaic) type failed; from the leaves affected by chlorotic ringspot a mixture of AMV and cherry leaf roll virus was identified. In addition, the polyetiological nature of “spring” mosaic and necrotic mosaic of lilac, in which bacteriumPseudomonas syringae van Hall, was found is dealt with. The TBSV was also identified in the isolate of necrotic mosaic.Additional index words: Lilac ringspot, chlorotic ringspot, yellow ring, “spring” mosaic, necrotic mosaic, cherry leaf roll virus,Pseudomonas syringae van Hall.