Fi Hybrids Research Articles

Aminopyridinate–FI Hybrids, Their Hafnium and Titanium Complexes, and Their Application in the Living Polymerization of 1‐Hexene

Based on two well-established ligand systems, the aminopyridinato (Ap) and the phenoxyimine (FI) ligand systems, new Ap-FI hybrid ligands were developed. Four different Ap-FI hybrid ligands were synthesized through a simple condensation reaction and fully characterized. The reaction of hafnium tetrabenzyl with all four Ap-FI hybrid ligands exclusively led to mono(Ap-FI) complexes of the type [(Ap-FI)HfBn2 ]. The ligands acted as tetradentate dianionic chelates. Upon activation with tris(pentafluorophenyl)borane, the hafnium-dibenzyl complexes led to highly active catalysts for the polymerization of 1-hexene. Ultrahigh molecular weights and extremely narrow polydispersities support the living nature of this polymerization process. A possible deactivation product of the hafnium catalysts was characterized by single-crystal X-ray analysis and is discussed. The coordination modes of these new ligands were studied with the help of model titanium complexes. The reaction of titanium(IV) isopropoxide with ligand 1 led to a mono(Ap-FI) complex, which showed the desired fac-mer coordination mode. Titanium (IV) isopropoxide reacted with ligand 4 to give a complex of the type [(ApH-FI)2 Ti(OiPr)2 ], which featured the ligand in its monoanionic form. The two titanium complexes were characterized by X-ray crystal-structure analysis.

Pathogenesis of experimental lupus nephritis: a role foranti-basement membrane and anti-tubular brush border antibodiesin murine chronic graft-versus-hostdisease

The pathogenesis of renal involvement was studied in murine chronic graft-versus-host disease (GVHD), which is a model for human systemic lupus erythematosus. GVHD was induced by four i.v. injections of lymphocytes from DBA/2 donor mice into (C57BL/10 x DBA/2)F1 hybrids at 3-4-day intervals. Two weeks after the first injection, antibodies were found to have been deposited in the mesangium and along the glomerular basement membrane (GBM) in a linear arrangement, which changed to a granular pattern after 6-8 weeks. In this stage, large electron-dense complexes were present both subepithelially and subendothelially along the GBM. Proteinuria increased up to 11,300 +/- 2140 micrograms/18 h. Indirect immunofluorescence studies and ELISA showed that sera and kidney eluates contained autoantibodies directed against nuclear antigens and GBM component laminin as well as against renal tubular epithelial antigens (RTE). The specificity of the anti-RTE antibodies was further characterized by the use of absorption techniques as well as immunoblotting. The early linear immunofluorescence pattern seems to be associated with glomerular binding of anti-GBM antibodies, while electron-dense complex formation in later stages may be induced by the superimposed deposition of anti-RTE antibodies. Similar phenomena were recently described in Heymann's nephritis in the rat, a model for human membranous nephropathy.

Graft-versus-host reactions in the rat mimic toxin-induced autoimmunity

Gold salts, D-penicillamine or mercurials induce autoimmunity in Brown Norway (BN) rats and provoke an immunosuppression in Lewis (LEW) rats. It has been suggested that immunologically mediated manifestations induced by drugs could result from graft-versus-host (GVH) like reactions. We show that BN spleen cells transferred into (LEW x BN)F1 hybrids induce a chronic GVH reaction (GVHR). This reaction led to an autoimmune disease quite similar to that induced by drugs in BN rats. In both situations, a common part of the B cell repertoire is triggered. In contrast, LEW spleen cells transferred into (LEW x BN)F1 hybrids provoke a lethal GVHR. This is to be compared with the CD8-mediated immunosuppression observed in LEW rats injected with HgCl2. These findings are in agreement with the prediction that immune dysregulation induced by drugs leads to GVH-like reactions either stimulatory or suppressive depending upon the strain tested.

Cytogenetic control of a hybrid zone between two Sorex araneus chromosome races before breeding season

Two chromosome races of common shrew, Moscow and Seliger, differ in the arm combination in 11 diagnostic chromosomes (Robertsonian metacentrics/acrocentrics). Homozygotes of both pure races, simple Robertsonian heterozygotes of Seliger race, and complex heterozygotes (FI hybrids) were detected in the found earlier between hybrid zone of these races, in the spring before the breeding seasonbreeding season. The g/oheterozygote was first discovered in race Seliger, whose chromosome formula typically contains acrocentrics g and o. The m/q heterozygote was recorded for the second time. Meiosis was studied in 16 males representing five detected karyotypic categories. No abnormal in pairing of homologs in either sex trivalent common for the species (XY1Y2) or autosome trivalents (g/o and m/q) was detected at diakinesis--metaphase I. Two hybrids displayed a theoretically expected and unimpaired meiotic configuration in a form of a very long chain comprising 11 monobrachial homologs (g/gm/mq/qp/pr/rk/ki/ih/hn/no/o). The results are discussed in terms of hypotheses on fertility of complex heterozygotes and limited gene flow in hybrid zone.

Morphological Characteristics and Isozyme Analysis of Triploid Achenes Obtained in the F2 Generation of Interspecific Hybrids between Lactuca sativa L. and L. saligna L.

Seven (18%) and 4 (6.2%) individuals from 39 and 65 F2 progenies obtained from the two interspecific FI hybrids between Lactuca saligna L. and L. sativa L. cv. Bronze were found to be spontaneous triploids. The length (mm) and weight (mg) of achenes formed on L. sativa, L.saligna and their F, hybrids were 4.01, 1.04; 2.70, 0.35; and 4.41 mm, 1.33 mg, respectively, and those of achenes obtained from L. saligna × L. sativa was 2.51 mm and 0.29 mg. The size of achenes obtained on the Fj hybrids ranged from 3.3 to 6.2 mm and 0.2 to 2.4 mg. The size of the F2 triploid seeds from the FI hybrids were classified into 2 groups; 5 triploids with small achene (0.7-1.1 mg) and the remaining 6 triploids with even heavier achene than L. sativa (>1.8 mg). The phenotype of 5 isozyme loci studied, Got-l, Pgi-l, Pgi-2, Pdh-1, and Pdh-2, always showed the 4 : 4 : 1 in band intensity in the triploids, which enabled us to analyze the genotypes. When the gene of L. sativa was named 'l' and that of L. saligna, 'g', all triploids were always heterozygous in the 5 isozyme loci, ggl or gll ; this suggests that triploids resulted from a union of a reduced gamete with an unreduced gamete. The triploids from small achenes were ggl in almost all of the five loci, whereas those from the large achenes were gll. Thus, the curious combinations between achene size and the genotypes indicate that the survival rate of individuals with the distorted combination of genes to one of the two parent species is higher than that with the random combination.

Appearance of the Unexpected Triploids in the Hybrid Progeny between Lettuce, Lactuca sativa and its Wild Relatives, L. saligna

Interspecific hybrids between Lactuca saligna and L. sativa cv. Bronze were obtained only when L. saligna was used as a seed parent. The seed set ratio of the Fj hybrid was very low (12.0%), however, their seed germination rate was 87.5%. In pollen mother cells of the Ft hybrids, univalent chromosomes were observed at metaphase I and the number of chiasma at diakinesis was fewer than their parental species. At pollen tetrad stage, the number of microspores of FI hybrids varied between 2 and 6. In some F2 hybrids, distorted staining intensities showed a 4:4:1 ratio in all or some of the 5 isozyme loci, suggesting that they were triploids or aneuploids, respectively. The triploids in F2 progeny were screened by flow cytometric analysis at the 2- week-old seedling stage. Microscopic observation of chromosome revealed that 14 of 103 F2 plants were found to be triploid, 2n=3x=27; no aneuploid plants were observed indicating that aneuploids do not survive until the 3- to 4-week-old seedling stage.

Shoot organogenesis from cotyledons of sunflower

The experiment was conducted in order to study the regeneration potential of cotyledon explants from some Iranian inbred lines of sunflower (Helian- thus annuus L.) and their Fj hybrids. Cotyledons of 2-day-old seedlings of three cytoplasmic male sterile inbred lines used as female (CMS 24, CMS 31 and CMS 60/52) and five inbred lines used as male (R-81.1, R-92, R-97, R-201 and R-232) and finally their 15 FI hybrids were plated on shoot induction medium, Murashige and Skoog (MS) containing 3% sucrose, 0.5% agar-agar and different concentrations of BAP and NAA. Analysis of variance showed significant differences for all organogenesis traits studied among parental genotypes and Fj hybrids, hormone combination treatments and genotype x hormone combination treatment interaction. Shoot organogenesis was optimized on MS medium with 1 mg I"1 BAP and 1 mg I"1 NAA. Interaction "(CMS 24 x R-201) x T2" showed the highest values for number of explants shooting per 100 explants plated (55%). Interaction "R- 92 x T2" showed the highest value for average number of shoots per explants plated (8.65). Interaction "R-81.1 x T2" showed the highest value for average number of shoots per explants shooting (23). Interaction "CMS 24 x T2" showed the highest value for number of explants rooting per 100 explants plated (35%).

ADVENTITIOUS REGENERATION IN ROOT CULTURE OF A SELECTION OF PELARGONIUM X HORTORUM CULTIVARS: AN ASSESSMENT OF CAULOGENIC POTENTIAL AND GENETIC STABILITY

Root explants from twenty two Pelargonium x hortorum FI hybrids were assessed for their caulogenic potential in vitro in response to media containing 4.4 g 1 -1 Murashige and Skoog (1962) basal medium containing 30 g 1 -1 sucrose. 8 g 1 -1 agar and varying concentrations of the growth regulators tri-iodobenzoic acid (TIBA) and thidiazuron (TDZ) at pH 5.8. Caulogenic potential varied from zero to five shoots per explant. Twenty of the FI hybrids produced shoots. At least 50 rooted shoots from the control and root derived population for twenty genotypes were established in vivo and assessed visually for morphological uniformity up to flowering. Visual examination showed no signs of morphological variation with respect to leaf shape, petal shape, flower colour and plant habit except for cvs. Pink Elite and Red Elite. Progeny derived from the latter had 5.5 % and 10 % plants, with variable leaf shape, respectively.

Efficiency in the use of phosphorus, nitrogen and potassium in topless faba beans (Vicia faba L.) – variability and inheritance*

AbstractIn a field experiment with topless faba beans, parental inbred lines and FI hybrids of a 7 × 7‐diallel were evaluated for traits related to the P, N and K efficiency. In addition, the parental inbreds were cultivated in a pot experiment at two P levels (100 vs. 700 mg P per pot). Significant heterosis for grain yield, uptake and utilization efficiency of nutrients in the field experiment highlighted the enhancement of nutrient efficiency in the hybrids. Amongst both parental inbreds and hybrids, significant genotypic variation was found for nearly all recorded traits. In the diallel analysis, the GCA effects generally proved to be highly significant and in most cases considerably higher than the SCA effects. In the pot experiment, grain yield ranking of the parental lines at the high P level (= P700) was very similar to that in the field experiment, whereas at the low P level (= P100, – P deficiency) the ranking of the lines changed considerably. Correspondingly, the P level‐line interaction was highly significant. High tolerance towards P deficiency was found for those two parental inbreds derived from cultivars bred under Syrian conditions. At the high P supply, P efficiency was more favoured by a high P uptake, but at P deficiency by a high internal P utilization.

HETEROSIS STUDIES IN BITTERGOURD(Momordica charantia)

Four lines were crossed with fifteen testers and the resultant sixty hybrid combinations, were evaluated along with their parents for heterosis, for fruit yield and their component characters. Observations were recorded on 12 yield component characters. Appreciable amount of heterosis was observed for all the characters under study. The Fi hybrids L3 x Ti (Pusa Visesh x MC.13) L2 x Ta (MC. 84 x MDU.1), and L1 x T) (DFH. 21 x MC.13) gave the highest fruit yield per vine and they showed 65.74, 61.92 and 48.04 per cent heterosis for yield over the standard variety (MC.84). The best performing F1 hybrid of the study L3 x T1 (Pusa Visesh x MC.13) recorded 65.74 per cent heter osis over the standard variety (MC.84) and 49.00 per cent heterosis over the better parent (MC.13).

Meiosis and Pollen Viability in Helianthus tuberosus L. and its Hybrids with Cultivated Sunflower

AbstractThe hexaploid species of Helianthus tuberosus is a potential source of resistance to several sunflower pathogens. But crossed with cultivated sunflower, it produces F, hybrids which have low values of fertility or even full sterility.Pollen viability and meiotic features were studied in 17 populations of the species H. tuberosus and in F1 hybrids. Significant differences in pollen viability existed between populations (47.1–98.8%). In the 15 FI hybrids, plant fertility ranged from 0 to 100 per combination, while pollen viability ranged from 12.4 to 57.1.Meiosis was almost normal in the analyzed species, and irregular in the F, hybrids. The highest percentage of meiocytes was with bivalents (85.9), but univalents (0.3) and multivalents (13.8) occurred as well. In metaphase and anaphase, the percentage of meiocytes with fast and lagging chromosomes was high. In anaphase, chromosome bridges were detected in 9.9 of the meiocytes.

Isolement reproducteur par homogamie entre deux « races d'habitat » sympatriques chez Drosophila melanogaster

Two races of D. melanogaster, morphologically identical, have been detected in the Brazzaville district (Congo). One (Loua = L), from the countryside, feeds and reproduces on manihot. The other (Kronenbourg = K) is found in the city bars and breweries, breeding on beer residues in empty bottles. These two populations can be distinguished by their genotypes at the Adh locus. The Kronenbourg population harbors 85 % of the F allele, while the frequency of this allele is less than 5 % in Loua. It is therefore easy to recognize them by mere electrophoresis. Under laboratory conditions, fertile FI and F2 hybrids are easily obtained. In natural conditions L and K remain separated. Behaviour plays probably a major role in reducing the gene flow through habitat choice and sexual behaviour. Sexual behaviour of these two races was analysed in laboratory. Sexual activity and mating choices were investigated by performing tests with four individuals (one male and one female of each race). In all tests, virgin adults were used. The L flies of both sexes exhibited a lower sexual activity than the K’s. Moreover, a significant homogamy independent of sexual activity was evidenced. It is the first time that such a phenomenon is found in D. melanogaster. This observation is of particular interest, since it concerns two sympatric races.

Estimates of Additive Genetic Effects, Maternal Genetic Effects, Individual Heterosis, Maternal Heterosis, and Egg Cytoplasmic Effects for Growth in Tilapia nilotica

AbstractLengths and weights of Auburn University‐Egypt and Auburn University‐Ivory Coast strains of Tilapia nilotica and their F1 F2, and backcross hybrids were analyzed by multiple regression to estimate strain additive genetic effects, strain maternal genetic effects, individual heterosis (specific combining ability), maternal heterosis, and strain egg cytoplasmic effects for growth to determine why heterosis of the F2 and backcross hybrids was greater than that of the FI hybrids. Individual heterosis and maternal heterosis made the greatest contributions to growth. The F2 and backcross hybrids were larger than the F1 hybrids because of maternal heterosis. Regression coefficients were used to predict growth for any possible hybrid combination. Egypt ♀× Ivory Coast ♂ FI hybrid females backcrossed to Egypt males and Egypt ♀× Ivory Coast ♂ F2 hybrids were the largest groups evaluated in this study and were also predicted to have faster growth rates than any other possible Egypt‐Ivory Coast hybrid.

Experimental hybridization ofBarbus barbusandBarbus meridionalis: physiological, morphological, and genetic aspects

Resume Philippart. J.-C., P. Berrebi. Aquat. Living Resour. 1990, 3, 325-332. FI hybrids were produced by crossing, in artificial conditions, female Barbus barbus and male B. meridionalis. Results from the gcnetic study dcscribing enzymatic patterns produced after electrophoresis of experimental FI hybrids confirmed a great part of the original interpretation of patterns observed in the natural population. Morphological studies which exarnined denticle length on the last hard ray of the dorsal fin (well developed in B. barbus and absent in B. meridionalis), showed that F1 hybrids' values were not exactly intermediate between the parental values. Up to two years old, experimental hybrids displayed identical growth rates and sexual dimorphism of length (in favour of the females) as B. barbus growing in the same conditions. At this age, in female hybrids, the ovaries matured and produced fertilizable ovules: in male hybrids, the testicles were morphologically normal but no sperm was produced. If this sterility is confirmed in the rcciprocal cross (male B. barbus x female B. meridionalis), the phenomenon would be an essential feature in understanding this hybridization.

Further studies on chromosome 15 trisomy in murine T-cell lymphomas: mapping of the relevant chromosome segment.

Trisomy 15 is the most common chromosomal aberration in murine T-cell lymphomas. The relevant chromosomal region responsible for the growth advantage of the 15-trisomic cell has not been defined. In order to map this region, we have induced thymic lymphomas by chemical carcinogens (DMBA or MNU) in mice with 2 different constitutional translocations, T(7;15)9H homozygotes and [T(7;15)9H X T(5;15)4Ad] FI hybrids. Twenty-two tumors developed in 90 carcinogen-treated mice. Among the 14 cytogenetically analyzed thymic lymphomas, 4 were diploid and 5 were aneuploid, with no chromosome-15-associated changes. Five lymphomas showed partial duplication of chromosome 15. Four of them have duplicated the segment distal to the C/DI breakpoint of T9H, while the 5th carried an interstitial duplication of the D2 sub-band of the T(7;15) translocation chromosome. These findings suggest that the duplication of the D 2/3 region, known to contain the c-myc and the pvt-I genes (Banerjee et al., 1985), rather than other regions of chromosome 15, contributes to the development and/or progression of murine T-cell leukemias.

Inheritance of Six Yield Components of Winter Wheat (Triticum aestivum L.)

Inheritance of Six Yield Components of Winter Wheat (Triticum aestivum L.)

Intergeneric Hybrids and Amphiploids between Pseudoroegneria spicata and Critesion violaceum

Diploid (2n = 14) Pseudoroegneria spicata ssp. inermis (genome formula, SS; formerly in Agropyron) was hybridized with diploid (2n = 14) Critesion violaceum (genome formula, HH; formerly in Hordeum). The hybrids (genome formula, SH) were morphologically intermediate to the parents. Mean chromosome associations of 7.28I, 3.11II, 0.16III, and 0.05IV were observed at metaphase I in 208 cells from four hybrids. Of the bivalents, 90% were rod configurations leading to a mean chiasma per arm of 0.269. The hybrids were completely sterile. The SSHH amphiploid derivatives were morphologically like the FI hybrids and were partially fertile, averaging 2.6 seeds per spike. At metaphase I, the amphiploids averaged 4.01I, 11.37II, 0.26III, 0.09IV, and 0.03V in 160 cells. Many progeny of the amphiploids were natural outcrosses to other species growing in the same field nursery. At least nine outcross hybrids occurred with Agropyron cristatum (2n = 14; genome formula, PP) and even more with Critesion brevisubulatum (2n = 28; genome formula, HHHH). These two hybrid combinations, whose identities were established on morphological and cytological grounds, were also analyzed at metaphase I. Data from hybrids, C0 and C1 amphiploids, and outcross hybrids led to the conclusions that (1) the S, H, and P genomes are distinctly different but contain some residual homologies, and (2) SSHH amphiploids are segmental alloploids.

Experimental diabetes in mice infected with coxsackie viruses

The influence of Coxsackie B4 and AI3 viruses on the pancreas of mice (resistant and susceptible to diabetes) was studied. Glucose intolerance and changes in the synthesis of immunoreactive insulin were detected in all the treated groups of animals. Biochemical changes were more prominent in male DBA/2 mice, infected with Coxsackie B4 virus, in FI (CBA X C57Bl/6) hybrids and in female DBA/2 mice infected with Coxsackie AI3 virus and alloxan.

A Second Edible Okra Species, and its Hybrids with Common Okra

Seventeen accessions of a West African okra species were observed in Puerto Rico, and were hybridized with the common okra species, Abelmoschus esculentus. The accessions are larger plants than common okra, but with shorter internodes. They also differ in numerous morphological and physiological characteristics. Most are more daylength sensitive than common okra. The Fi hybrids of the two species are quite sterile, although in some cases a few germinable F2 seeds are produced. Back-crosses, on the other hand, are more fertile than the Fx hybrids, and fertility is almost complete in the BC2. Some evidence was found of cytoplasmic interaction with chromosomes in production of sterile BC hybrids, a possibly useful tool for future use. Meanwhile, the transfer of genes from the new species to common okra appears very feasible.

Developing Superior Inbreds from Exotic Germplasm of Pearl Millet1

This study was designed to compare two methods of developing pearl millet, Pennisetum amerlcanum (L.) Leeke., inbreds from exotic germplasm: selfing within an introduction (I) or selfing within F1 hybrids of the introduction crossed with an elite inbred (I × E). Elite inbreds Tilt (T) 8, T13, T18, T23, T26 (T18A and T23A), 71 introductions from India, and 250 introductions from Nigeria were used in this study. Bulking of selfed seed from single heads of 12 to 15 plants, used to plant each succeeding generation, exerted some selection for selfed seed production. No other selection was practiced. Forage yields of FI hybrids of I and I × E inbreds crossed on T18A and T23A (cytoplasmic male‐sterile inbreds) were used to assess 321 I and I × E inbreds developed. Results indicate that crossing exotic germplasm with elite lines before selfing may be expected to increase inbred seed yields up to 50% and materially reduce the loss of inbreds due to poor seed set. Selection for other elite traits, not practiced here, could have given added advantage to I × E inbreds. Although the greatest difference between I and I × E hybrid forage yields (1,232 kg/ha) favored I × E inbreds, I × E inbreds generally gave no higher yielding hybrids than I inbreds.