Orchiectomy reduces susceptibility to renal ischemic injury: a role for heat shock proteins

In previous studies we demonstrated that the presence of testosterone, rather than the absence of estrogen, plays a critical role in gender differences in kidney ischemia/reperfusion (I/R) injury. Although molecular chaperones such as heat shock proteins (HSPs) have been implicated as protective agents in the pathophysiology of I/R injury, their roles in gender differences in susceptibility to renal I/R injury remain to be defined. Here we demonstrate that orchiectomy increases the basal and post-ischemic expression of HSP-27 in kidney tubular epithelial cells, but not HSP-72, glucose-regulated protein (GRP)-78 or GRP-94 expression. Orchiectomy prevents the disruption of the actin cytoskeleton and renal functional disorders induced by I/R, when compared with intact male mice or orchiectomized mice treated with dihydrotestosterone, a non-aromatizable isoform of testosterone. Thus, the protection afforded by orchiectomy is associated with increased expression of HSP-27, a heat shock protein important for maintenance of actin cytoskeletal integrity. These findings indicate that testosterone inhibits the heat shock response and may provide a new paradigm for design of therapies for I/R injury.     

The chromosomal location of peroxidase isozymes of the wheat kernel

Summary The analysis of the individual parts of the Triticum aestivum L. kernel yields a total of 11 peroxidase isozymes: m, n, a, c, d₁, d, d₂, e, f, g and h (in order from faster to slower migration). Isozymes a, c and d are found in the endosperm (Ed) and seed coats (C), while m, n, d₁, d₂, e, f, g and h are peculiar to the embryo and scutellum (E + S). The use of the nullitetrasomic and ditellosomic series of Chinese Spring wheat allows peroxidase isozymes to be associated with specific chromosome arms. Isozymes a, c and d (Ed) are associated with chromosome arms 7D^S, 4B^L and 7A^S; whereas isozymes m, d₂, e and f are associated with chromosome arms 3D^S, 3B^L, 3D^L and 3D^L, respecitvely. Thus, the E + S isozymes are associated with homoeology group 3 and the Ed isozymes with homoeology groups 7 (a and d isozymes) or 4 (c isozymes).     

Microsatellite tagging of the leaf rust resistance gene <Emphasis Type="Italic">Lr16</Emphasis> on wheat chromosome 2BSc

Leaf rust, caused by Puccinia triticina, is one of the most damaging diseases of wheat worldwide. Lr16 is a widely deployed leaf rust resistance gene effective at the seedling stage. Although virulence to Lr16 exists in the Canadian P. triticina population, Lr16 provides a level of partial resistance in the field. The primary objective of this study was to identify markers linked to Lr16 that are suitable for marker-assisted selection (MAS). Lr16 was tagged with microsatellite markers on the distal end of chromosome 2BS in three mapping populations. Seven microsatellite loci mapped within 10 cM of Lr16, with the map distances varying among populations. Xwmc764 was the closest microsatellite locus to Lr16, and mapped 1, 9, and 3 cM away in the RL4452/AC Domain, BW278/AC Foremost, and HY644/McKenzie mapping populations, respectively. Lr16 was the terminal locus mapped in all three populations. Xwmc764, Xgwm210, and Xwmc661 were the most suitable markers for selection of Lr16 because they had simple PCR profiles, numerous alleles, high polymorphism information content (PIC), and were tightly linked to Lr16. Twenty-eight spring wheat lines were evaluated for leaf rust reaction with the P. triticina virulence phenotypes MBDS, MBRJ, and MGBJ, and analyzed with five microsatellite markers tightly linked to Lr16. There was good agreement between leaf rust infection type (IT) data and the microsatellite allele data. Microsatellite markers were useful for postulating Lr16 in wheat lines with multiple leaf rust resistance genes.     

The effect of polyamines on protein kinase activities of wheat (Triticum aestivum) L. anthers

Protein kinase activities were extracted from anther tissue of wheat (Triticum aestivum L. cv. Zaragoza) and characterized with regard to the effects of polyamines, second messengers and plant growth hormones. The protein kinases were inhibited by polyamines and cyclic nucleotides, but were stimulated by the addition of auxins, gibberellic acid and kinetin. The dominant polyamine-sensitive kinase activity was partially purified and characterized. The optimal pH of the reaction was 7.5 to 8.0 and casein was the preferred exogenous substrate. Polyamines were inhibiting in the decreasing order of putrecine > spermidine > spermine. The results are discussed against the context of the anther culture technique.     

Utilization of chemical inducers of resistance and Cryptococcus flavescens OH 182.9 to reduce Fusarium head blight under greenhouse conditions

Four chemicals [salicylic acid (SA), sodium salt of salicylic acid (NaSA), isonicotinic acid (INA), and DL-β-amino-n-butyric acid (BABA)] and the yeast antagonist Cryptococcus flavescens (=C. nodaensis nomen nudum) OH 182.9 were evaluated separately or together for the ability to reduce Fusarium head blight (FHB) of wheat in the greenhouse. When sprayed onto wheat heads at 3 days prior to pathogen challenge with Gibberella zeae, NaSA and INA at 10 mM significantly reduced FHB severity compared to the non-treated disease control. Applied at concentrations of 1 and 5 mM at 3 days before pathogen challenge, NaSA or INA in combination with OH 182.9 did not significantly reduce FHB severity compared to either treatment alone, though the lowest disease severity values frequently were associated with the combination treatments. When sprayed onto wheat heads just beginning to emerge from boot at 10 days prior to pathogen inoculation, NaSA, INA, and BABA at 1 mM significantly reduced FHB severity indicating that induced systemic resistance was at least partially responsible for the reduction of FHB disease. Induced FHB resistance was achieved by treating wheat with INA at concentrations as low as 0.1 mM. In only one instance was 100-kernel weight affected by any chemical or combination of chemicals with OH 182.9 treatment. Data from our studies in the greenhouse suggest that chemical inducers can induce resistance in wheat against FHB, and that further efforts are warranted to explore the potential of improved control of FHB disease by incorporating chemical inducers with the FHB biocontrol agent OH 182.9.     

Molecular analysis of plants regenerated from embryogenic cultures of wheat (Triticum aestivum L.)

Total DNAs of plants regenerated from immature embryo-derived 2-month-old embryogenic calli of wheat (cultivars Florida 302, Chris, Pavon, RH770019) were probed with six maize mitochondrial genes (atpA, atp6, apt9, coxI, coxII, rrn18-rrn5), three hypervariable wheat mitochondrial clones (K, K3, X2), five random pearl millet mitochondrial clones (4A9, 4D1, 4D12, 4E1, 4E11) and the often-used wheat Nor locus probe (pTA71), in order to assess the molecular changes induced in vitro. In addition, protoplast-derived plants, and 24-month-old embryogenic and non-embryogenic calli and cell suspension cultures of Florida 302 were also analyzed. No variation was revealed by the wheat or millet mitochondrial clones. Qualitative variation was detected in the nonembryogenic suspension culture by three maize mitochondrial genes (coxI, rrn18-rrn5, atp6). A callus-specific 3.8-kb Hind III fragment was detected in all four cultivars after hybridization with the coxI gene. The organization of the Nor locus of the plants regenerated from Florida 302 and Chris was stable when compared to their respective control plants and calli. The Nor locus in regenerants of Pavon and RH, on the other hand, was found to be variable. However, Nor locus variability was not observed in 14 individual seed-derived control plants from either Pavon or RH sources. In Pavon, a 3.6-kb Taq I or a 5.6-kb Bam HI+ Eco RI fragment was lost after regeneration. In one of the RH regenerants, which lost a fragment, an additional fragment was observed.     

The endophytic fungi from wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

In order to study the species composition of endophytes from wheat healthy plants in Buenos Aires Province (Argentina) and to determine their infection frequencies from leaves, stems, glumes and grains, wheat plants were collected from five cultivars at five growth stages from crop emergence to harvest. A total of 1,750 plant segments (leaves, stems, glumes and grains) were processed from the five wheat cultivars at five growth stages, and 722 isolates of endophytic fungi recovered were identified as 30 fungal genera. Alternaria alternata, Cladosporium herbarum, Epicoccum nigrum, Cryptococcus sp., Rhodotorula rubra, Penicillium sp. and Fusarium graminearum were the fungi that showed the highest colonization frequency (CF%) in all the tissues and organs analysed. The number of taxa isolated was greater in the leaves than those in the other organs analysed.     

An efficient method for in vitro regeneration from immature inflorescence explants of Canadian wheat cultivars

Fertile, green plants were regenerated from immature inflorescence explants from each of four Canadian wheat cultivars. The cultivars were representative of four classes of Canadian wheat. Explants from immature inflorescences of three size ranges were cultured on two types of media: MSI/MSR, which contains 1650 mg l^-1 NH₄NO₃and sucrose as a carbon source, and BII/BIR, which contains 250 mg l^-1 NH₄NO₃and maltose as a carbon source. Regeneration from all cultivars was significantly better on BII/BIR media than on MSI/MSR media. On BII/BIR media, `AC Karma', `Plenty', and `Fielder' gave the highest number of shoots per 10 explants, where the explants were derived from immature inflorescences 5.1 to 10.0 mm in length. 'Columbus' did not regenerate on MSI/MSR medium, and regenerated poorly on BII/BIR medium. Differences were found between cultivars with regard to the number of regenerant plants produced with the best treatments: `Plenty' produced 16.1 shoots per 10 explants, `AC Karma' 12.4, `Fielder' 6.4, and `Columbus' 2.2.     

Molecular characterization of the fate of transgenes in transformed wheat (Triticum aestivum L.)

Molecular analysis of the transgenes bar and gus was carried out over successive generations in six independent transgenic lines of wheat, until the plants attained homozygosity. Data on expression and integration of the transgenes is presented. Five of the lines were found to be stably transformed, duly transferring the transgenes to the next generation. The copy number of the transgenes varied from one to five in the different lines. One line was unstable, first losing expression of and then eliminating both the transgenes in R3 plants. Although the gus gene was detected in all the lines, GUS expression had been lost in R2 plants of all but one line. Rearrangement of transgene sequences was observed, but it had no effect on gene expression. All the stable lines were found to segregate for transgene activity in a Mendelian fashion.     

Isolation and identification of Triticum aestivum L. em. Thell. cv Chinese Spring-T. peregrinum Hackel disomic chromosome addition lines

Analyses of RFLPs, isozymes, morphological markers and chromosome pairing were used to isolate 12 Triticum aestivum cv Chinese Spring (genomes A, B, and D)-T. peregrinum (genomes S^v and U^v) disomic chromosome addition lines. The evidence obtained indicates that each of the 12 lines contains an intact pair of T. peregrinum chromosomes. One monosomic addition line, believed to contain an intact 6S^v chromosome, was also isolated. A CS-7U^v chromosome addition line was not obtained. Syntenic relationships in common with the standard Triticeae arrangement were found for five of the seven S^v genome chromosomes. The exceptions were 4S^v and 7S^v. A reciprocal translocation exists between 4S¹ and 7S¹ in T. longissimum and evidence was obtained that the same translocation exists in T. peregrinum. In contrast, evidence for syntenic relationships in common with the standard Triticeae arrangements were found for only one U^v chromosome of T. peregrinum.; namely, chromosome 2U^v. All other U^v genome chromosomes are involved in at least one translocation, and the same translocations were found in the U genome of T. umbellulatum. Evidence was also obtained indicating that the centromeric regions of 4U and 4U^v are homoeologous to the centromeric regions of Triticeae homoeologous group-6 chromosomes, that the centromeric regions of 6U and 6U^v are homoeologous to the centromeric regions of group-4 chromosomes, and that 4U and 4U^v are more closely related overall to Triticeae homoeologous group-6 chromosomes than they are to group-4 chromosomes.     

Silica content ofTriticum aestivum L. in relation to humic acid concentrations in the soil

Summary The weathering of soil minerals by humic acids is linked with increased silica content of wheat plants.     

Protein accumulation,RNA and soluble amino nitrogen content in developing endosperm of two varieties of Triticum aestivum with high and low protein seed

Summary The kinetics of protein accumulation, the variation in RNA, the soluble amino nitrogen content of developing endosperm of two varieties of Triticum aestivum, with high and low protein content in the mature seed, suggest a possible relation between maintenance of the RNA content and the ability to synthesize protein. A sudden halt in protein accumulation is observed as the RNA starts to decrease. The hypothesis is also advanced that maintenance of the RNA content might, in turn, be dependent on the presence, in the endosperm of developing wheat seed, of a certain level of soluble amino nitrogen which could then play the role of limiting factor for protein synthesis.Publication No. 491 from the Divisione Applicazione delle Radiazioni del C.N.E.N., SCN Casaccia, S.M. di Galeria, Rome, Italy.     

Wheat anther culture: effect of genotype and environmental conditions

Twenty-two cultivars and lines of winter and spring wheat (Triticum aestivum L.) were studied, most for the first time, for their anther culture response. The response was genotype dependent. Plants grown in the field gave higher callus induction frequency than those grown in the greenhouse and the controlled environment chamber. Donor plants grown in a season of low drought stress as compared to a season of severe drought stress resulted in a higher frequency of callus induction. Spherical microcalli were observed in two wheat genotypes in some of only those anthers that were placed with only one loculus in contact with the medium. Wheat lines that were more responsive to anther culture were identified.     

小麦R2R3-MYB转录因子TaMYB3-4D的克隆及功能分析

MYB转录因子是植物最大的转录因子家族之一,广泛参与植物各种生理生化过程。该研究通过对小麦基因组测序数据库进行同源搜索,利用电子克隆技术从紫色籽粒小麦品种‘高原115’中分离得到了一个新的MYB基因TaMYB3-4 D。结果表明,TaMYB3-4D仅含有一个内含子,其编码蛋白含有2个连续的MYB结构域,为典型的R2R3-MYB蛋白。TaMYB3-4D系统发生关系上与调控花青素合成的MYB基因亲缘关系较近。TaMYB3-4 D与bHLH基因ZmR瞬时表达能够诱导白色胚芽鞘中花青素的合成。此外,TaMYB3-4 D基因仅在‘高原115’含花青素的种皮和胚芽鞘中表达,在根、茎、叶中均未表达。研究表明,TaMYB3-4 D基因是一个具有调控花青素合成代谢功能的R2R3-MYB基因,很有可能参与小麦花青素的生物合成。     

Enzyme activities associated with developing wheat(Triticum aestivum L.) grain amyloplasts

Intact amyloplasts from endosperm of developing wheat grains have been isolated by first preparing the protoplasts and then fractionating the lysate of the protoplasts on percoll and ficoll gradients, respectively. Amyloplasts isolated as above were functional and not contaminated by cytosol or by organelles likely to be involved in carbohydrate metabolism. The enzyme distribution studies indicated that ADP-glucose pyrophosphorylase and starch synthase were confined to amyloplasts, whereas invertase, sucrose synthase, UDP-glucose pyrophosphorylase, hexokinase, phosphofructokinase-2 and fructose-2,6-P₂ase were absent fro the amyloplast and mainly confined to the cytosol. Triose-P isomerase, glyceraldehyde-3-P dehydrogenase, phosphohexose isomerase, phosphoglucomutase, phosphofructokinase, aldolase, PPi-fructose-6-P-1 phosphotransferase, and fructose-l,6-P₂ase, though predominantly cytosolic, were also present in the amyloplast. Based on distribution of enzymes, a probable pathway for starch biosynthesis in amyloplasts of developing wheat grains has been proposed.