Primer-mediated in situ detection of the B-hordein gene cluster on barley chromosome 1H

Rapid detection of yeast rRNA genes with primed in situ (PRINS) labeling

In yeast, rRNA genes can be detected with the FISH technique using rRNA gene probes. This technique yields reliable, reproducible and precise results, but is time-consuming. Here, the primed in situ DNA synthesis (PRINS) procedure has been optimized for rapid detection of yeast rRNA genes. PRINS, which is as sensitive as PCR and allows cytological localization of analyzed sequences, can be adapted for various screening tests requiring fast labeling of rRNA genes.

A novel approach for developing resistance in rice against phloem limited viruses by antagonizing the phloem feeding hemipteran vectors

Rice production is known to be severely affected by virus transmitting rice pests, brown planthopper (BPH) and green leafhopper (GLH) of the order hemiptera, feeding by phloem abstraction. ASAL, a novel lectin from leaves of garlic (Allium sativum) was previously demonstrated to be toxic towards hemipteran pests when administered in artificial diet as well as in ASAL expressing transgenic plants. In this report ASAL was targeted under the control of phloem-specific Agrobacterium rolC and rice sucrose synthase-1 (RSs1) promoters at the insect feeding site into popular rice cultivar, susceptible to hemipteran pests. PCR, Southern blot and C-PRINS analyses of transgenic plants have confirmed stable T-DNA integration and the transgenes were co-segregated among self-fertilized progenies. The T(0) and T(1) plants, harbouring single copy of intact T-DNA expression cassette, exhibit stable expression of ASAL in northern and western blot analyses. ELISA showed that the level of expressed ASAL was as high as 1.01% of total soluble protein. Immunohistofluorescence localization of ASAL depicted the expected expression patterns regulated by each promoter type. In-planta bioassay studies revealed that transgenic ASAL adversely affect survival, growth and population of BPH and GLH. GLH resistant T(1) plants were further evaluated for the incidence of tungro disease, caused by co-infection of GLH vectored Rice tungro bacilliform virus (RTBV) and Rice tungro spherical virus (RTSV), which appeared to be dramatically reduced. The result presented here is the first report of such GLH mediated resistance to infection by RTBV/RTSV in ASAL expressing transgenic rice plant.

Multicolor PRINS and multicolor PNA

Both PRimed IN Situ (PRINS) and Peptide Nucleic Acid (PNA) technologies have emerged as research techniques, but they have quickly evolved to applications in biological diagnosis assays. The two procedures now constitute efficient alternatives to the conventional fluorescence in situ hybridization (FISH) procedure for in situ chromosome identification and aneuploidy detection. They present several advantages (specificity, speed, discriminating ability) that make them very attractive for a number of cytogenetic purposes. Multicolor PRINS and PNA protocols have been described for the specific identification of human chromosomes. Various applications have already been developed in human genetics and new adaptations are ongoing.

Transgenic rice expressing Allium sativum leaf lectin with enhanced resistance against sap-sucking insect pests

Mannose binding Allium sativum leaf agglutinin (ASAL) has been shown to be antifeedant and insecticidal against sap-sucking insects. In the present investigation, ASAL coding sequence was expressed under the control of CaMV35S promoter in a chimeric gene cassette containing plant selection marker, hpt and gusA reporter gene of pCAMBIA1301 binary vector in an elite indica rice cv. IR64. Many fertile transgenic plants were generated using scutellar calli as initial explants through Agrobacterium-mediated transformation technology. GUS activity was observed in selected calli and in mature plants. Transformation frequency was calculated to be approximately 12.1%+/-0.351 (mean +/- SE). Southern blot analyses revealed the integration of ASAL gene into rice genome with a predominant single copy insertion. Transgene localization was detected on chromosomes of transformed plants using PRINS and C-PRINS techniques. Northern and western blot analyses determined the expression of transgene in transformed lines. ELISA analyses estimated ASAL expression up to 0.72 and 0.67% of total soluble protein in T0 and T1 plants, respectively. Survival and fecundity of brown planthopper and green leafhopper were reduced to 36% (P < 0.01), 32% (P < 0.05) and 40.5, 29.5% (P < 0.001), respectively, when tested on selected plants in comparison to control plants. Specific binding of expressed ASAL to receptor proteins of insect gut was analysed. Analysis of T1 progenies confirmed the inheritance of the transgenes. Thus, ASAL promises to be a potential component in insect resistance rice breeding programme.

Rapid chromosome detection by PRINS in human sperm

Primed in situ (PRINS) labeling may be used for direct estimation of disomy rate in human sperm. We combined the PRINS procedure with a rapid and efficient NaOH pretreatment allowing simultaneous decondensation and denaturation of sperm nuclei. This enabled double labeling of human sperm within a 2-hr time span. Chromosome-specific primers have been defined for most human chromosomes, including those most frequently involved in aneuploidy. Using the dual-color PRINS method, we estimated incidences of disomy for 15 autosomes and the sex chromosomes in sperm samples from 6 normal fertile men. The frequency of disomy ranged from 0.28% to 0.36%. There were no significant interchromosomal differences in disomy rate, but chromosome 21 displayed a higher incidence of nondisjunction than did the other chromosomes.

Labelling telomeres of cereals, grasses and clover by primed in situ DNA labelling

Primed in situ DNA labelling (PRINS) labels the telomeres of Avena, Triticum, Secale, Hordeum, Lolium, Festuca and Trifolium when primers are used that correspond to the repeat unit of Arabidopsis telomeres. There are interstitial sites labelled in a Lolium x Festuca hybrid.

Organization of retro-element and stem-loop repeat families in the genomes and nuclei of cereals

Sequences homologous to the retro-element BIS-1 and the stem-loop repeat Hi-10 are present in the genomes of a number of cereal species. A detailed characterization of these elements indicated that they are non-randomly organized in the genomes of at least two of these species, namely barley and rye. In contrast to the BIS-1 retro-elements, the stem-loop repeats are also non-randomly organized into discrete domains in interphase nuclei from barley and rye. Features of the organization of these repeats along chromosomes and within interphase nuclei of rye, barley and rice are discussed.

Chromosome painting in plants: in situ hybridization with a DNA probe from a specific microdissected chromosome arm of common wheat

We report here on the successful painting of a specific plant chromosome within its own genome. Isochromosomes for the long arm of chromosome 5 of the wheat B genome (5BL) were microdissected from first meiotic metaphase spreads of a monoisosomic 5BL line of the common wheat Triticum aestivum cv. Chinese Spring. The dissected isochromosomes were amplified by degenerate oligonucleotide-primed PCR in a single tube reaction. The amplified DNA was used as a complex probe mixture for fluorescent in situ hybridization on first meiotic metaphase spreads of lines carrying 5BL as a distinctive marker. Hybridization signals were observed, specifically, along the entire 5BL. In some of the cells, labeling was also detected in two bivalents, presumably those of the 5B "homoeologues" (partial homologues) found in common wheat (5A and 5D). The probe also revealed discrete domains in tapetal nuclei at interphase, further supporting the probe's high specificity. These data suggest that chromosome and homoeologous group-specific sequences are more abundant in 5BL than genome-specific sequences. Chromosome-painting probes, such as the one described here for 5BL, can facilitate the study of chromosome evolution in polyploid wheat.

A family of related sequences associated with (TTTAGGG)n repeats are located in the interstitial regions of wheat chromosomes

A family of related sequences associated with (TTTAGGG)n repeats has been cloned from the wheat cultivar Chinese Spring. These sequences reveal a high level of polymorphism between wheat varieties when used as restriction fragment length polymorphism (RFLP) probes. Although this family of sequences contains motifs homologous to the repeats in the telomeres of wheat, they are located at interstitial sites on wheat chromosomes.