Differential anaphase-I behaviour between wheat and rye univalents in triticale-wheat hybrid plants

The chromosomes of the D genome of wheat and the genome R of rye can be distinguished at meiosis by C-banding in triticale-wheat hybrid plants. All members of both genomes almost exclusively formed univalents at metaphase I. However, at anaphase I the frequencies of equationally dividing chromosomes were higher for rye than for wheat chromosomes. The differential centromere behaviour at anaphase I is ascribed to differences in the time at which wheat and rye univalents are formed during the first meiotic prophase.     

Role of cell-mediated immunity in the resistance to experimental sporotrichosis in mice

The in vitro activity of several new imidazoles, cloconazole, sulconazole, butoconazole, isoconazole and fenticonazole, were compared with those of amphothericin B, flucytosine, and three azoles: econazole, miconazole and ketoconazole against isolates of pathogenic Candida. A total of 186 clinical isolates of 10 species of the genus Candida and two culture collection strains were tested by an agar-dilution technique. Isoconazole was the most active azole, followed by butoconazole and sulconazole. Differences between some of the species in their susceptibility to the antifungal agents were noted. Sulconazole and cloconazole had the highest activity in vitro against 106 isolates of C. albicans. Butoconazole and isoconazole were also very active against isolates of C. albicans, and were the most active azole compounds against 80 isolates of Candida spp.     

Most of the homoeologous pairing at metaphase I in wheat-rye hybrids is not chiasmatic

The use of telomeric C-bands in wheat-rye hybrids has made it possible to distinguish three types of wheat-wheat (1B^L) and wheat-rye associations (a, end-to-end extremely distal; b, end-to-ed distal; and c, interstitial) between homoeologous chromosomes at different metaphase I stages (early, middle and late) and also to estimate the actual recombination frequencies for such associations at anaphase I. There was a decrease of the a and b association frequencies during the different metaphase I stages, whereas the c type remained without variation in all stages. A good fit between the frequencies of c associations at metaphase I and the number of recombinant chromosomes at anaphase I, assuming a maximum of one chiasma per bond, was found; however, there was no correspondence between metaphase I and anaphase I data when all associations (a + b + c) were considered. In addition, rye-rye homologous pairing was observed at metaphase I, but no evidence for rye-rye recombination was found at anaphase I. The results indicate that most of end-to-end (a and b) homoeologous and nonhomologous associations are actually nonchiasmatic and are a remnant of prophase pairing.     

Phorbol ester inhibits phosphoinositide hydrolysis and calcium mobilization in cultured astrocytoma cells

In cultured human 1321N1 astrocytoma cells, muscarinic receptor stimulation leads to phosphoinositide hydrolysis, formation of inositol phosphates, and mobilization of intracellular Ca2+. Treatment of these cells with 1 microM 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA) completely blocks the carbachol-stimulated formation of [3H]inositol mono-, bis-, and trisphosphate ( [3H]InsP, [3H]InsP2, and [3H]InsP3). The concentrations of PMA that give half-maximal and 100% inhibition of carbachol-induced [3H]InsP formation are 3 nM and 0.5 microM, respectively. Inactive phorbol esters (4 alpha-phorbol 12,13-didecanoate and 4 beta-phorbol), at 1 microM, do not inhibit carbachol-stimulated [3H]InsP formation. The KD of the muscarinic receptor for [3H]N-methyl scopolamine is unchanged by PMA treatment, while the IC50 for carbachol is modestly increased. PMA treatment also abolishes carbachol-induced 45Ca2+ efflux from 1321N1 cells. The concomitant loss of InsP3 formation and Ca2+ mobilization is strong evidence in support of a causal relationship between these two responses. In addition, our finding that PMA blocks hormone-stimulated phosphoinositide turnover suggests that there may be feedback regulation of phosphoinositide metabolism through the Ca2+- and phospholipid-dependent protein kinase.     

Meiotic behaviour of Un,D and R genomes in the amphiploid Aegilops ventricosa -Secale cereale and the parental species

Summary Meiotic pairing frequencies of the Un and D genomes of Ae. ventricosa and the R of S. cereale could be easily established at metaphase I in Aegilops ventricosa — Secale cereale amphiploid plants as well as in its parental species by using the C-banding technique procedure. The results show a high diminution of chromosome pairing for all genomes in the amphiploid with respect to its parental species probably due to C-heterochromatin content and/or genotypic or cryptic interactions between the three genomes.     

DETERMINATION OF GUSTATORY SUCROSE THRESHOLD IN WATER BY USE OF A LINEAR SUCROSE GRADIENT

A novel experimental method was developed which allows the determination of the threshold concentration of sucrose by use of a linear sucrose gradient in water. With this method a continuous tasting of the test-liquid is possible. A panel of 15 persons experienced in taste-testing was used. Three gradients of different steepness were applied: 0 to 1.5% (w/w) sucrose in 2 min (I), 3 min (II) and 4 min (III). The results of the new method were compared with those of the standard method (DIN). With gradients I and II we found values which were significantly higher than those of the standard method (I: 0.49% (w/w); II: 0.46% (w/w); DIN: 0.31% (w/w)), whereas with gradient III the same threshold value was found as with the DIN-Method (III: 0.32% (w/w)).     

Relationship between the levels of wheat-rye metaphase I chromosomal pairing and recombination revealed by GISH

The metaphase I and anaphase I stages of meiosis of wheat×rye hybrids carrying the ph1b mutation were analyzed by genomic in situ hybridization. This technique allows distinction between three different types of wheat-rye associations in metaphase I configurations as well as detection of wheat-rye recombinant chromosomes in anaphase I cells. The frequency of associations between wheat and rye chromosomes greatly exceeded the level of wheat-rye recombination found in the three hybrids examined. Extremely distal associations, which account for about 50% of the total wheat-rye metaphase I chromosomal pairing, can explain such a discrepancy between metaphase I and anaphase I data. It is further discussed whether these associations reflect very distally located chiasmata or nonchiasmatic pairing. The sizes of the segments exchanged in wheat-rye recombinant chromosomes provide cytological evidence that wheat-rye recombination is restricted to the distal chromosomal regions. Received: 24 August 1995; in revised form: 27 February 1996 / Accepted: 28 March 1996     

Mapping of genes controlling seed storage-proteins and cytological markers on chromosome 1R of rye

Summary Rye secalins, telomeric C-bands, and telocentric chromosomes were used as markers in the progeny of a test-cross in order to determine the position of seed storage-protein genes Glu-R1 and Gli-R1 with respect to the centromere and both telomeres of chromosome 1 R in rye. These genes were linked to the centromere (32.35±3.28% and 36.27±3.37% recombination, respectively). Glu-R1 was loosely linked to the telomere of the long arm (43.63±3.47% recombination), while Gli-R1 was closely linked to the telomere of the short arm (9.80±2.08% recombination). This finding supports the possibility that rye - and -secalin genes may be located on the satellites, as has been described in wheat for genes that code similar proteins. The importance of metaphase-I pairing failure and its consequences for the estimation of the recombination fraction are also discussed.