Development and characterization of <Emphasis Type="Italic">japonica</Emphasis> rice lines carrying the brown planthopper-resistance genes <Emphasis Type="Italic">BPH12</Emphasis> and <Emphasis Type="Italic">BPH6</Emphasis>

The brown planthopper (Nilaparvata lugens Stål; BPH) has become a severe constraint on rice production. Identification and pyramiding BPH-resistance genes is an economical and effective solution to increase the resistance level of rice varieties. All the BPH-resistance genes identified to date have been from indica rice or wild species. The BPH12 gene in the indica rice accession B14 is derived from the wild species Oryza latifolia. Using an F₂ population from a cross between the indica cultivar 93-11 and B14, we mapped the BPH12 gene to a 1.9-cM region on chromosome 4, flanked by the markers RM16459 and RM1305. In this population, BPH12 appeared to be partially dominant and explained 73.8% of the phenotypic variance in BPH resistance. A near-isogenic line (NIL) containing the BPH12 locus in the background of the susceptible japonica variety Nipponbare was developed and crossed with a NIL carrying BPH6 to generate a pyramid line (PYL) with both genes. BPH insects showed significant differences in non-preference in comparisons between the lines harboring resistance genes (NILs and PYL) and Nipponbare. BPH growth and development were inhibited and survival rates were lower on the NIL-BPH12 and NIL-BPH6 plants compared to the recurrent parent Nipponbare. PYL-BPH6 + BPH12 exhibited 46.4, 26.8 and 72.1% reductions in population growth rates (PGR) compared to NIL-BPH12, NIL-BPH6 and Nipponbare, respectively. Furthermore, insect survival rates were the lowest on the PYL-BPH6 + BPH12 plants. These results demonstrated that pyramiding different BPH-resistance genes resulted in stronger antixenotic and antibiotic effects on the BPH insects. This gene pyramiding strategy should be of great benefit for the breeding of BPH-resistant japonica rice varieties.     

<Emphasis Type="Italic">Ty</Emphasis>1<Emphasis Type="Italic">/copia</Emphasis>- and <Emphasis Type="Italic">Ty</Emphasis>3<Emphasis Type="Italic">/gypsy</Emphasis>-like DNA sequences in <Emphasis Type="Italic">Helianthus </Emphasis>species

Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes.     

<Emphasis Type="Italic">Galleria</Emphasis><Emphasis Type="Italic">mellonella</Emphasis> are Resistant to <Emphasis Type="Italic">Pneumocystis</Emphasis><Emphasis Type="Italic">murina</Emphasis> Infection

Studying Pneumocystis has proven to be a challenge from the perspective of propagating a significant amount of the pathogen in a facile manner. The study of several fungal pathogens has been aided by the use of invertebrate model hosts. Our efforts to infect the invertebrate larvae Galleria mellonella with Pneumocystis proved futile since P. murina neither caused disease nor was able to proliferate within G. mellonella. It did, however, show that the pathogen could be rapidly cleared from the host.     

Development of expressed sequence tag-derived microsatellite markers for <Emphasis Type="Italic">Saccharina</Emphasis> (<Emphasis Type="Italic">Laminaria</Emphasis>) <Emphasis Type="Italic">japonica</Emphasis>

Expressed sequence tag-derived microsatellite markers (EST-SSR) were generated and characterized in Laminaria japonica using data mining from updated public EST databases and polymorphism testing. Fifty-eight of 578 ESTs (10.0%) containing various repeat motifs were used to design polymerase chain reaction (PCR) amplification primers. A total of 12 pairs of primer were generated and used in the PCR amplification. Alleles per locus ranged from two to ten (average of 5.7). The observed heterozygosities and expected heterozygosities were from 0.045 to 0.543 and from 0.056 to 0.814, respectively. All loci were in Hardy–Weinberg equilibrium and no linkage disequilibrium was detected. These robust, informative, and potentially transferable polymorphic markers appear suitable for population, genetic, parentage, and mapping studies of L. japonica.     

Identification of <Emphasis Type="Italic">mokB</Emphasis> involved in monacolin K biosynthesis in <Emphasis Type="Italic">Monascus pilosus</Emphasis>

Monacolin K (MK), which is widely used as an antihypercholesterolemia medicine, is produced as a fungal secondary metabolite through the polyketide pathway. The MK biosynthetic gene cluster proposed for Monascus pilosus BCRC38072 was also identified in M. pilosus NBRC4480. The mokB gene, located at the end of the putative gene cluster and possibly encoding polyketide synthase, was disrupted. The mokB disruptant did not produce MK, but accumulated an intermediate that was confirmed to be monacolin J, indicating that mokB encodes the polyketide synthase responsible for the biosynthesis of side-chain diketide moiety.     

<Emphasis Type="Italic">Agrobacterium</Emphasis><Emphasis Type="Italic">tumefaciens</Emphasis>-mediated transformation of callus cells of <Emphasis Type="Italic">Crataegus</Emphasis><Emphasis Type="Italic">aronia</Emphasis>

A genetic transformation system has been developed for callus cells of Crataegus aronia using Agrobacterium tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with 5 mg l⁻¹ Indole-3-butyric acid (IBA) and 0.5 mg l⁻¹ 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red colored callus was obtained on MS medium supplemented with 2 mg l⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l⁻¹ kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l⁻¹ hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this is the first time to report an Agrobacterium-mediated transformation system in Crataegus aronia.     

Revision of the <Emphasis Type="Italic">Serrulati</Emphasis> species of <Emphasis Type="Italic">Penstemon</Emphasis> section <Emphasis Type="Italic">Saccanthera</Emphasis> subsection <Emphasis Type="Italic">Serrulati</Emphasis>

A revision of Penstemon sect. Saccanthera subsect. Serrulati includes a new species (P. salmonensis), a new variety (P. triphyllus var. infernalis), and the elevation of a subspecies to species (P. curtiflorus), bringing the total number of species to eight, which are keyed and described, complete with nomenclature and type citations.     

Regulation of stipule development by <Emphasis Type="Italic">COCHLEATA</Emphasis> and <Emphasis Type="Italic">STIPULE</Emphasis>-<Emphasis Type="Italic">REDUCED</Emphasis> genes in pea <Emphasis Type="Italic">Pisum sativum</Emphasis>

Pisum sativum L., the garden pea crop plant, is serving as the unique model for genetic analyses of morphogenetic development of stipule, the lateral organ formed on either side of the junction of leafblade petiole and stem at nodes. The stipule reduced (st) and cochleata (coch) stipule mutations and afila (af), tendril-less (tl), multifoliate-pinna (mfp) and unifoliata-tendrilled acacia (uni-tac) leafblade mutations were variously combined and the recombinant genotypes were quantitatively phenotyped for stipule morphology at both vegetative and reproductive nodes. The observations suggest a role of master regulator to COCH in stipule development. COCH is essential for initiation, growth and development of stipule, represses the UNI-TAC, AF, TL and MFP led leafblade-like morphogenetic pathway for compound stipule and together with ST mediates the developmental pathway for peltate-shaped simple wild-type stipule. It is also shown that stipule is an autonomous lateral organ, like a leafblade and secondary inflorescence.     

The <Emphasis Type="Italic">Caenorhabditis</Emphasis><Emphasis Type="Italic">briggsae</Emphasis> genome contains active <Emphasis Type="Italic">CbmaT1</Emphasis> and <Emphasis Type="Italic">Tcb1</Emphasis> transposons

The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae.     

The iron-sulfur cluster assembly genes <Emphasis Type="Italic">iscS</Emphasis> and <Emphasis Type="Italic">iscU</Emphasis> of <Emphasis Type="Italic">Entamoeba histolytica</Emphasis> were acquired by horizontal gene transfer

Background  

Iron-sulfur (FeS) proteins are present in all living organisms and play important roles in electron transport and metalloenzyme catalysis. The maturation of FeS proteins in eukaryotes is an essential function of mitochondria, but little is known about this process in amitochondriate eukaryotes. Here we report on the identification and analysis of two genes encoding critical FeS cluster (Isc) biosynthetic proteins from the amitochondriate human pathogen Entamoeba histolytica.     

Bioavailability of zinc in the sediment to the estuarine amphipod <Emphasis Type="Italic">Grandidierella</Emphasis><Emphasis Type="Italic">japonica</Emphasis>

The utility of interstitial water concentrations of metals and simultaneously extracted metals/acid-volatile sulfide differences (SEM–AVS) in two seasons were investigated to explain the biological availability of zinc in sediments to benthic organisms exposed in the laboratory. The amphipod Grandidierella japonica was exposed, in 10-day acute toxicity tests, to clean sediment spiked with zinc to obtain nominal treatments ranging from 0.25 to 74.4 mol g^–1 dry weight with respect to the molar difference between SEM_Zn and AVS. When the molar difference between SEM_Zn and AVS (i.e., SEM–AVS) was <0 mol g^–1, the concentration of zinc in the sediment interstitial water was low and few adverse effects were observed for any of the biological endpoints measured. Conversely, when SEM_Zn–AVS exceeded 0 mol g^–1, the concentration of zinc in the interstitial water and amphipod mortality increased. These data compare favorably with observations made in short-term exposures and thus support the use of AVS as a normalization phase for predicting toxicity in metal-contaminated sediments in different season.