[Application value of CT examination of lymph node short diameter in evaluating cardia-left gastric lymph node metastasis in thoracic esophageal squamous cell carcinoma].

Objective: To investigate the application value of computed tomography (CT) examination of lymph node short diameter in evaluating cardia-left gastric lymph node metastasis in thoracic esophageal squamous cell carcinoma (ESCC). Methods: A total of 477 patients with primary thoracic ESCC who underwent surgical treatment in the Affiliated Cancer Hospital of Zhengzhou University from January 2013 to December 2017 were collected. All of them underwent McKeown esophagectomy plus complete two-field or three-field lymph node dissection. Picture archiving and communication system were used to measure the largest cardia-left gastric lymph node short diameter in preoperative CT images. The postoperative pathological diagnosis results of cardia-left gastric lymph node were used as the gold standard. Receiver operating characteristic (ROC) curve was used to evaluate the efficacy of CT lymph node short diameter in detecting the metastasis of cardia-left gastric lymph node in thoracic ESCC, and determine the optimal cut-off value. Results: The median short diameter of the largest cardia-left gastric lymph node was 4.1 mm in 477 patients, and the largest cardia-left gastric lymph node short diameter was less than 3 mm in 155 cases (32.5%). Sixty-eight patients had cardia-left gastric lymph node metastases, of which 38 had paracardial node metastases and 41 had left gastric node metastases. The lymph node ratios of paracardial node and left gastric node were 4.0% (60/1 511) and 3.3% (62/1 887), respectively. ROC curve analysis showed that the area under the curve of CT lymph node short diameter for evaluating cardia-left gastric lymph node metastasis was 0.941 (95% CI: 0.904-0.977; P<0.05). The optimal cut-off value of CT examination of the cardia-left gastric lymph node short diameter was 6 mm, and the corresponding sensitivity, specificity and accuracy were 85.3%, 91.7%, and 90.8%, respectively. Conclusion: CT examination of lymph node short diameter can be a good evaluation of cardia-left gastric lymph node metastasis in thoracic ESCC, and the optimal cut-off value is 6 mm.

[Prevalence and influencing factors of Enterobius vermicularis infections among children in Fanxian County of Henan Province in 2019].

OBJECTIVE: To investigate the prevalence and influencing factors of Enterobius vermicularis infections among children in Fanxian County, Henan Province in 2019, so as to provide insights into the management of enterobiasis. METHODS: Five kindergartens were selected in urban and rural areas of Fanxian County, Henan Province using the stratified sampling method in 2019, and a census of E. vermicularis infections was performed among all children in the kindergartens. E. vermicularis eggs were detected using adhesive and scotch cellophane-tape anal swab methods, and the basic characteristics of children and their families, health habits and the kindergartens' information were investigated with questionnaires. Logistic regression analysis was used to investigate the risk factors and protective factors of pinworm infection in children. RESULTS: A total of 671 children were tested, and the mean prevalence of E. vermicularis infections was 15.50% (104/671). The prevalence of E. vermicularis infections was higher among children in rural kindergartens (28.13%, 72/256) than in urban kindergartens (7.71%, 32/415) (χ2 = 50.380, P < 0.01), and greater in private kindergartens (32.26%, 60/186) than in public kindergartens (9.07%, 44/485) (χ2 = 55.183, P < 0.01). There was no gender-specific prevalence of E. vermicularis infections among children (χ2 = 1.442, P > 0.05), and the prevalence of E. vermicularis infections presented a tendency towards a rise with age (χ2trend = 8.373, P < 0.05) and school grade (χ2trend = 30.274, P < 0.05). Logistic regression analysis identified rural kindergartens and high grades as risk factors, and separate washing of children's and adults' cloths, frequent bathing and frequent dinnerware disinfection in kindergartens as protective factors for E. vermicularis infections among children. In addition, there was no significant difference in the detection of E. vermicularis infections among children by using adhesive (73.08%, 76/104) and scotch cellophane-tape anal swab methods (56.73%, 59/104) (χ2 = 3.959, P > 0.05). CONCLUSIONS: The prevalence of E. vermicularis infection is high among children in Fanxian Country, Henan Province. Health education and surveillance of enterobiasis are required to be intensified among children in rural kindergartens and senior grades and their parents and teachers.

Early third trimester maternal response to glucose challenge and pregnancy outcome in Chinese women-relationship between upper distribution level and recommended diagnostic criteria.

BACKGROUND/OBJECTIVES: The objective of this study was to examine the relationship between upper distribution levels of glucose values in the 75-g oral glucose tolerance test (OGTT) and recommended diagnostic criteria for gestational diabetes mellitus (GDM) and adverse pregnancy outcomes. SUBJECTS/METHODS: The distribution of the OGTT 2-h values of 13,501 pregnant women, which were below the World Health Organization (WHO) threshold for overt diabetes mellitus (DM), and managed in one teaching hospital in China, was reviewed and related to maternal characteristics and pregnancy outcomes. RESULTS: For the entire group, the 90th and 95th percentile values of the OGTT 2-h glucose level, respectively, were close to the diagnostic cutoff values of the WHO and International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria. For adverse maternal outcomes, glucose level above the 90th percentile value was associated with increased hypertensive disorders, whereas no difference was seen with cutoff using the 95th percentile value. For perinatal outcomes, the 90th percentile was associated with increased neonatal intensive care unit admission and hypoglycemia, whereas the 95th percentile showed in addition association with phototherapy for jaundice and 5th-minute Apgar score <7. Although no differences in the incidence of adverse pregnancy outcomes were found using the different cutoffs, the >95th percentile cutoff value would have missed out 33.3-56.7% of the cases of adverse outcomes that would otherwise have been attributed to GDM. CONCLUSIONS: Further studies are warranted to clarify which diagnostic criterion is most appropriate universally to identify adverse pregnancy outcomes attributed to GDM, and which could be mitigated with treatment specific for GDM.

Mercury (Hg2+) suppression of potassium currents of outer hair cells.

The heavy metal mercury (Hg(2+)) is an insidious environmental pollutant that causes toxic effects on sensory systems. It is well known that the group IIB divalent cation Hg(2+) is an inhibitor of the group I monovalent potassium (K(+)) cation pore-forming channel in several biological preparations. Here, we used the whole cell patch clamp technique on freshly isolated outer hair cells (OHCs) of the guinea pig cochlea to record outward K(+) currents and inward K(+) currents treated with mercuric chloride (HgCl(2)). HgCl(2) affected K(+) currents in a voltage- and dose-dependent manner. The effects of HgCl(2) at 1.0-100 microM are more pronounced on onset peak current than on steady-state end current. HgCl(2) depolarized also the resting membrane potential. Although the effect of HgCl(2) at 1.0 microM was partially washed out over several minutes, the effects at 10 and 100 microM were irreversible to washout. Since K(+) channels of OHCs are targets for HgCl(2) ototoxicity, this may lead to auditory transduction problems, including a loss in hearing sensitivity. A better understanding of fundamental mechanisms underlying K(+) channelopathies in OHCs due to HgCl(2) poisoning may lead to better preventive or therapeutic agents.

Lead (Pb2+) modulation of potassium currents of guinea pig outer hair cells.

Outer hair cells (OHC) are mechanosensitive sensory cells of the inner ear cochlea and are involved in modulating the activity of inner hair cells in the transduction of an acoustic stimulus. Potassium (K(+)) currents play an important role in the sensory transduction process. K(+) currents were recorded from acutely dissociated OHC obtained from the guinea pig organ of Corti. The whole-cell patch clamp technique was employed. We identified a channel that exhibited outward current of the delayed rectifier type (Kv). Kv channels mediating inward currents carried by potassium ions were also identified and took on the appearance of a previously described inwardly rectifying current. Lead (Pb(2+)) acetate at concentrations of 0.1, 1.0, 10, and 100 microM was bath applied. Time to activation for outward-going current was not affected by Pb(2+). The time course of Pb(2+) effects was seen as a dose-dependent reduction of K(+) current over time, with very little or no recovery after washout. Pb(2+) inhibited the outward Kv relative current with values of 0.10, 0.14, 0.18, and 0.30 at 0.1, 1.0, 10, and 100 microM, respectively. Pb(2+) did not modulate time to activation, peak current, or inactivation of inward I(K). The effects of Pb(2+) on the potassium currents of OHC are not remarkable and therefore OHC are probably not a major cause of purported peripheral hearing loss observed in Pb(2+)-exposed animals and humans.

Antifungal proteins and other mechanisms in the control of sorghum stalk rot and grain mold.

Research on antifungal proteins and other mechanisms that provide the biochemical basis for host-plant resistance to stalk rot and grain molds is reviewed in this paper. Stalk rot caused by Fusarium species leads to substantial yield loss due to poor grain filling and/or lodging. A transgenic sorghum expressing high levels of chitinase exhibited less stalk rot development when exposed to conidia of F. thapsinum. Grain mold of sorghum is associated with warm humid environments and results from colonization by several fungi (F. thapsinum, Curvularia lunata, and Alternaria alternata) of the developing caryopsis. The roles of several biochemical mechanisms (tannins, phenolic compounds, red pericarp, proteins, hard endosperm, and antifungal proteins) on grain mold resistance are discussed. Resistance mechanisms related to these compounds appear to be additive, and pyramiding of genes is a feasible approach to limit grain deterioration. Several experimental approaches are proposed to extend current findings.

[RFLP analysis of the effect of wide compatibility genes in Aus variety 'Dular'].

RFLP markers were employed to test whether the individuals possess wide compatibility genes (WCGs) in the progenies of Dular, which is one of the typical wide compatibility varieties in ecotype Aus rice. Meanwhile the characteristics of WCGs were also analysed. The results are shown as follows: (1) the effect of WCG at S-5 locus is better than the others, (2) the combination of different wide compatibility loci is obviously effective in increasing the spikelet fertility, (3) intraallelic interaction can cause japonica macrospore abortive, while interallelic interaction has some effects in fertility expression.

[Re-analysis of wide compatibility in rice].

Utilization of heterosis between rice subspecies has fascinated rice breeders for several decades. One of the main obstacles is the hybrid sterility in the F1 populations of subspecies crosses in rice. Wide compatibility varieties are considered to an important way to overcome the problem. But the genetics of the wide compatibility is controversial. This paper dealt with the problem through three kinds of triple crosses in which a wide compatibility variety, Ketan Nangka, was involved. Pollen fertility, spikelet fertility and the correlationship between the two fertilities were analyzed in the three kinds of triple crosses. The results suggested that male and female sterilities existed in indica-japonica hybrids at the same time, while the contribution of male sterility to spikelet fertility varied from cross to cross; The characteristic of wide compatibility in different triple crosses was coordinated with the hybrid sterility between the indica and japonica test varieties used; Ketan Nangka possessed the wide compatibility genes on the loci in which the male and female sterilities between the test varieties were involved; The genetics of wide compatibility gene S-5 fitted to one locus sporo-gametophytic interaction model.

[RFLP analysis on wide compatibility genes in rice variety dular of ecotype aus].

Dular is one of the typical wide compatibility varieties in ecotype Aus of rice. Genetic analysis on wide compatibility genes (WCG) from Dular based on triple crosses (indica//++Dular/japonica) was conducted. In the condition of being shaded for 7 days, the individual spikelet fertility segregated obviously, and the continuous distributions of spikelet fertility with a handful of peaks were observed. This suggested that the segregation of spikelet fertility in triple cross populations was controlled by one or more major genes, also modified by some minor genes. Based on 109 individuals of triple cross Nanjing 11 (indica)//++Dular/2533(japonica, a marker gene line, Rc and g), fertile and semisterile pools were set up by bulked segregant analysis, the RFLP analysis of the two pools led to the discovery of three chromosomal segments co-segregating with fertility. The one is on the interval RG213-C235 on chromosome 6. According to the previous studies, it may be the wide compatibility gene S5n. The other two were on the interval RG901-RG413 and G402-RG651 on chromosome 12, temporarily designated as Sd1(t)n and Sd2(t)n, respectively. Because of the continuous distribution for spikelet fertility, we also used a quantitative model to evaluate the effects of those three loci. On the basis of interval analysis with Mapmaker/QTL, 32.3% of the phenotypic variance associated with spikelet fertility was explained by the S5n (LOD = 9.03), and the other two chromosomal segments were responsible for 10.5%(LOD = 2.61) and 10.9%(LOD = 2.14) phenotypic variance, respectively. The results demonstrated that the wide compatibility variety Dular contained three WCGs. To introgress the three WCGs into a restorer line or an abortive line will overcome the hybrid sterility barrier of indica/japonica crosses, and the precise RFLP mapping will be useful for breeders to accumulate a few genes of interest into one cultivar by means of molecular marker assisted selection.

[Genetic analysis of gelatinization temperature in rice via microsatellite(SSR) markers].

Rice gelatinization temperature is an important character contributing to cooking quality. Here the inheritance of gelatinization temperature (GT), which was represented by alkali spreading value (ASV), was reported. Two parents, Balilla (japonica variety) and Nantehao (indica variety), which were significantly different on GT-ASV, were selected to construct a backcross population Balilla/Nantehao//Balilla containing 142 individuals. And ASV was investigated in the population, a continuous distribution with two obvious peaks was observed. It indicated that GT-ASV was controlled by one major gene, also modified by some minor genes. In order to map the major and minor genes and estimate the effects of genes. A total of 119 SSR markers were employed to construct a linkage map; further a genome-wide detection was carried out by interval mapping method. The results showed that 6 QTLs were detected, of which, qASV6-1 located on chromosome 6 was a major gene with 87.6% variance explained, and alleles from parent Nantehao could decrease the value. It shoud be the same locus as the alkali degeneration gene (alk). The other QTLs (qASV2, qASV3, qASV6-2, qASV9, and qASV11) all belong to minor genes, which were located on chromosome 2,3,6,9 and 11, respectively. In two parents, they carried the positive and negative alleles simultaneously. These results will be helpful for rice quality breeding and improvement.

[Chromosome location of a semidwarf gene sd-t in indica rice (O. sativa L.)].

For investigating the linkage group to which the semidwarf gene sd-t belongs, the crosses between Aitaiyin 2(ATY2), a variety of sd-t carrier in indica rice, and marker stocks as well as the trisomic lines of IR36 were made. The results indicated that the sd-t gene was linked to the marker genes Prp-b (Purple pericap b), lg(ligueless) and Wh(White hull). The recombination values estimated were 2.85% +/- 0.52% for sd-t to Prp-b, 27.90% +/- 3.81% for sd-t to lg and 38.62% +/- 2.99% for sd-t to Wh, respectively. It was inferred that the sd-t gene was located on chromosome 4 according to the established relationship between chromosomes and linkage groups.

Stimulation of large-conductance Ca2+-activated K+ channels by the Na+/Ca2+ exchanger inhibitor dichlorobenzamil in cultured human umbilical vein endothelial cells and mouse aortic smooth muscle cells.

We investigated the effects of the selective inhibitor of Na(+)/Ca(2+) exchanger (NCX), 2',4'- and 3',4'-dichlorobenzamil (DCB), on large-conductance Ca(2+)-activated K(+) (BK(Ca)) channels in cultured human umbilical vein endothelial cells (HUVECs) and fresh isolated mouse aortic smooth muscle cells (MASMCs) using the patch clamp techniques. Both kinds of DCB reversibly activated BK(Ca) currents in whole-cell clamped HUVECs or MASMCs. The EC(50) of 2',4'-DCB for BK(Ca) current activation in HUVECs was 2.64 +/- 0.10 muM. In inside-out and outside-out patches, 2',4'-DCB remarkably increased BK(Ca) channels activity. 2',4'-DCB increased open frequency, but had no significant effect on mean open time. In inside-out patches, 2',4'-DCB shifted the relationship curve between [Ca(2+)](i) and open probability (NP(o)) to the left; the [Ca(2+)](i) required to evoke half-maximal activation changed from 1087.45 +/- 142.91 nM to 500.24 +/- 66.83 nM by 10 muM 2',4'-DCB. In addition, 2',4'-DCB shifted the relationship curve between membrane potential and NP(o) to the left; the membrane potential to evoke half-maximal activation changed from 81.1 +/- 2.4 to 64.7 +/- 3.1 mV by 10 muM 2',4'-DCB. 3',4'-DCB also increased BK(Ca) channels activity. There was no significant difference in the effect of DCB on BK(Ca) channels between both excised patches. These results suggested that 2',4'- and 3',4'-DCB activate BK(Ca) channels activity in HUVECs and MASMCs by increasing the sensitivity of BK(Ca) channels to cytosolic free Ca(2+) and membrane potential. Our report would provide a consideration if they are used as NCX blocker in vascular endothelial cells or smooth muscle cells.

Efficient genetic transformation of Sorghum using a visual screening marker.

To transform grain sorghum (Sorghum bicolor (L.) Moench) with a visual reporter gene (gfp) and a target gene (tlp), three genotypes (two inbreds, Tx 430 and C401, and a commercial hybrid, Pioneer 8505) were used. We obtained a total of 1011 fertile transgenic plants from 61 independent callus lines, which were produced from 2463 zygotic immature embryos via Agrobacterium-mediated transformation. The reporter gene, gfp, encoding green fluorescent protein (GFP), was used as a visual screening marker, and the target gene, tlp, encoding thaumatin-like protein (TLP), was chosen for enhancing resistance to fungal diseases and drought. Both genes were under the control of the maize ubi 1 promoter in the binary vector pPZP201. A total of 320 plants showing GFP expression, derived from 45 calli, were selected and analyzed by Southern blot analysis. There was a 100% correlation between the GFP expression and the presence of the target gene, tlp, in these plants. Transgenic plants showing strong TLP expression were confirmed by Western blotting with antiserum specific for TLP. The transgene segregated in various ratios among progeny, which was confirmed by examining seedlings showing GFP fluorescence. The progeny also showed different copy numbers of transgenics. This report describes the successful use of GFP screening for efficient production of stably transformed sorghum plants without using antibiotics or herbicides as selection agents.

The genomic relationship between cultivated sorghum [Sorghum bicolor (L.) Moench] and Johnsongrass [S. halepense (L.) Pers.]: a re-evaluation.

The genomic relationship between cultivated sorghum [Sorghum bicolar (L.) Moench, race bicolor, De Wet, 2n=20] and Johnsongrass [S. halepense (L.) Pers., 2n=40] has been a subject of extensive studies. Nevertheless, there is no general consensus concerning the ploidy level and the number of genomes present in the two species. This research tested the validity of four major genomic models that have been proposed previously for the two species by studying chromosome behaviors in the parental species, 30-chromosome hybrids [sorghum, (2n=20) x Johnsongrass, (2n=40)], 40-chromosome hybrids [sorghum, (2n=40) x Johnsongrass, (2n=40)] and 60-chromosome amphiploids. Chromosome pairings of amphiploids are reported for the first time. Chromosomes of cultivated sorghums paired exclusively as 10 bivalents, whereas Johnsongrass had a maximum configuration of 5 ring quadrivalents with occasional hexavalents and octovalents. In contrast, 40-chromosome cultivated sorghum had up to 9 ring quadrivalents and 1 hexavalent. Pairing in the 30-chromosome hybrids showed a maximum of 10 trivalents, and that in the 40-chromosome hybrids exhibited 8 quadrivalents, 5 of which were rings, together with a few hexavalents. Amphiploid plants showed up to 3 ring hexavalents, 1 chain hexavalent and a chain of 12 chromosomes. The data suggest that cultivated sorghum is a tetraploid species with the genomic formula AAB1B1, and Johnsongrass is a segmental auto-allo-octoploid, AAAA B1B1B2B2. The model is further substantiated by chromosome pairing in amphiploid plants whose proposed genomic formula is AAAAAA B1B1B1B1 B2B2.

[Longdan jiechuan decoction in the management of bronchial asthma].

Ninety-six cases of bronchial asthma (male 44, female 52; age: 7-73) were treated with oral Longdan Jiechuan Decoction. After one year follow up, the clinical efficacy was as follows: clinical curative rate 29.2%; marked effective rate 29.2% with the total effective rate of 97.9%, which were significantly higher than that in the control group treated with routine WM(P less than 0.01). The average PEF(288.2 +/- 92.5, 306.8 +/- 98.4 L/min) in the herbal group after half year and one year orally administered was significantly higher than the value of premedication (199.0 +/- 81.4 L/min) (P less than 0.01) and that of the control group (P less than 0.001). Patients condition might be further improved if the decoction were given according to the circadian rhythm of ventilation.

Comparative physical mapping of the 18S-5.8S-26S rDNA in three sorghum species.

The physical locations of the 18S-5.8S-26S rDNA sequences were examined in three sorghum species by fluorescence in situ hybridization (FISH) using biotin-labeled heterologous 18S-5.8S-26S rDNA probe (pTa71). Each 18S-5.8S-26S rDNA locus occurred at two sites on the chromosomes in Sorghum bicolor (2n = 20) and S. versicolor (2n = 10), but at four sites on the chromosomes of S. halepense (2n = 40) and the tetraploid S. versicolor (2n = 20). Positions of the rDNA loci varied from the interstitial to terminal position among the four accessions of the three sorghum species. The rDNA data are useful for investigation of chromosome evolution and phylogeny. This study excluded S. versicolor as the possible progenitor of S. bicolor.

Possible repetitive DNA markers for Eusorghum and Parasorghum and their potential use in examining phylogenetic hypotheses on the origin of Sorghum species.

Genomic structures of two major species in section Eusorghum (Sorghum), Sorghum bicolor and Sorghum halepense, and their phylogenetic relationships with a species in section Parasorghum, Sorghum versicolor, were studied by using cloned repetitive DNA sequences from the three species. Of the five repetitive DNA clones isolated from S. bicolor and S. halepense, four produced qualitatively similar hybridization patterns with detectable variations in copy numbers of some of the restriction fragments on the Southern blots of the two genomic DNAs. One clone was shown to be diagnostic for S. halepense. Molecular analysis at the DNA level indicates that S. bicolor and S. halepense have similar but not identical genomes, consonant with differences in karyotypes, meiotic chromosome behaviors, morphology, and physiology of the species. In addition to five repetitive clones isolated from S. bicolor and S. halepense, eight more sequences were cloned from S. versicolor. Nine clones were found to be specific for either S. bicolor and S. halepense or S. versicolor. The remaining four had a moderate to strong homology with sequences present in all Sorghum species studied. We speculate that the genome in the common ancestor of Sorghum has differentiated to give rise to genomes of at least three major chromosome sizes; large, medium, and small, as seen at present. Amplifications, eliminations, rearrangements, and new syntheses of repetitive sequences may have been involved in genome differentiation of these species. The results also suggest that the S. versicolor genome has strongly diverged from the genomes of the two species in section Eusorghum.

Using regression coefficient as a stability parameter in plant breeding programs.

Expanding the regression coefficient as stability parameter (Finlay and Wilkinson 1963) requires an unbiased interpretation of the parameter. Information on the covariances among the genotypes of the population must be specific, particularly when the assumed relatedness of the genotypes appears questionable. Such a problem, however, is not expected when the covariances between the genotypes are either zero or equal and possibly non zero.

Phylogenetic relationships of sorghum taxa inferred from mitochondrial DNA restriction fragment analysis.

To elucidate the evolutionary history and affinity of sorghum species, 41 sorghum taxa were analyzed using variability in mitochondrial DNA. Analysis of species relationships at the molecular level can provide additional data to supplement the existing classification based on morphological characters and may also furnish unexpected but useful information. Total DNA extracted from each of the sorghum accessions was digested with each of five restriction enzymes, BamHI, HindIII, EcoRI, EcoRV, and XbaI, and probed with five mitochondrial DNAs cloned from Sorghumbicolor. A total of 180 restriction fragments was detected by the 25 probe-enzyme combinations. Forty-three fragment bands were phylogenetically informative. Multiple correspondence analysis was performed to visualize associations among the accessions and suggested that section Eusorghum species may be divided into four groups, with Sorghumlaxiflorum (section Heterosorghum) and Sorghumnitidum (section Parasorghum) appearing as outliers. A phylogenetic tree was assembled from mitochondrial restriction fragment data. The taxa analyzed formed three major groups comprising section Heterosorghum (group I), section Parasorghum (group II), and all accessions in section Eusorghum (group III). Group III is further divided into four groups: (i) two sweet sorghums and shattercane; (ii) Sorghumhalepense, Sorghummiliaceum, Sorghumhewisonii, Sorghumaethiopicum, Sorghumverticilliflorum, and S. bicolor, including Sorghumsudanense (sudangrass), the Chinese Kaoliangs, and a number of commercial sorghum inbreds from the U.S.A.; (iii) Sorghumpropinquum; and (iv) Sorghumarundinaceum, Sorghumniloticum, Sorghumalmum, Sorghumcontroversum, and the Chinese material C-401 and 5-27. Results indicate that the analysis of fragmented mitochondrial DNA was diagnostic and useful in sorghum phylogenetic and taxonomic research at the species, subspecies, and race levels, and can complement results from those analyses using nuclear ribosomal DNA and chloroplast DNA that effectively distinguish taxa at species and genus levels. Key words : Sorghum, mitochondrial DNA, phylogeny, restriction fragment.

Effectiveness of ph gene in inducing homoeologous chromosome pairing in agrotricum.

We observed pairing, when the ph gene was present, between wheat (Triticum aestivum L. em. Thell.) chromosome 4B, and an Agropyron intermedium (Host) Beauv. chromosome (Ai) carrying a gene resistant to wheat streak mosaic (WSM). In a monosomic addition polyhaploid [2n = 22 = 19' + 5B' (ph) + 4B' + Ai'], we recorded an average of 4.1 bivalents and 0.3 trivalents per cell. Induced homoeologous pairing was most effective when both 5B chromosomes carrying ph gene were present. Our data suggest that chromosome 4B of wheat and the Agropyron chromosome (Ai) carrying a gene for resistance to WSM are homoeologous and that it is possible to use either ph mutant or nullisomic 5B stock to induce genetic recombination between the two chromosomes.