Vigor in an interspecific hybrid of sansevieria

F₁ hybrids of S. trifasciata x S. deserti were distinctly superior to either parent species in terms of total green yield, percent fiber leaves, fiber leaf yield and fiber yield in tests conducted on Everglades peat and Immokalee fine sand in south Florida. Apparently the hybrid vigor in the F₁’s can be accounted for by a combination of favorable growth factors from the 2 diverse parent species. Generally the fiber quality of the hybrids was equal to or better than the parents.     

Expression of the fragile (X) chromosome in an interspecific somatic cell hybrid

Interspecific somatic cell hybrids were constructed between a Chinese hamster lung cell line deficient in hypoxanthine phosphoribosyltransferase and two lymphoblastoid cultures (GM 4025 and GM 3200) from unrelated males affected with the fragile (X) syndrome. Thirteen independent colonies survived selection in hypoxanthine-azaserine, while only one colony survived selection in hypoxanthine-aminopterin-thymidine. One hybrid formed from GM 4025 was found to contain a human X chromosome as the only detectable human chromosome in the majority of cells analyzed. Induction of fragile (X) expression in this hybrid at frequencies up to 20% was achieved by treatments with 5-fluoro-2'-deoxyuridine (5 X 10(-8) M or 1 X 10(-7) M) or methotrexate (5 X 10(-6) or 1 X 10(-5) for 12 h. Use of the somatic cell hybrid system may allow study of the fragile (X) from different patients on a homogeneous xenogeneic background and may provide a better system for characterization of the fragile (X) at the biochemical and molecular level.     

Cadherin-mediated cell sorting not determined by binding or adhesion specificity.

Cadherin adhesion molecules play important roles in the establishment of tissue boundaries. Cells expressing different cadherins sort out from each other in cell aggregation assays. To determine the contribution of cadherin binding and adhesion specificity to the sorting process, we examined the adhesion of cells to different purified cadherin proteins. Chinese hamster ovary cell lines expressing one of four different cadherins were allowed to bind to the purified cadherin extracellular domains of either human E-cadherin or Xenopus C-cadherin, and the specificity of adhesion was compared with cell-sorting assays. None of the different cadherin-expressing cells exhibited any adhesive specificity toward either of the two purified cadherin substrates, even though these cadherins differ considerably in their primary sequence. In addition, all cells exhibited similar strengthening of adhesion on both substrates. However, this lack of adhesive specificity did not determine whether different cadherin-expressing cells would sort from each other, and the tendency to sort was not predictable by the extent of sequence diversity in their extracellular domains. These results show that cadherins are far more promiscuous in their adhesive-binding capacity than had been expected and that the ability to sort out must be determined by mechanisms other than simple adhesive-binding specificity.     

A new hereditary variant of the PGM1 erythrocyte enzyme system determined by isoelectric focusing

Summary A new variant of the PGM _a ¹ erythrocyte enzyme system not identical with the known variants of the system has been detected in the hemolyzed red blood cells of a healthy blood donor by isoelectric focusing. Using this technique the variant is represented by two bands, a strong and slow one more cathodically located than the a3 band and a weak one in the position of the a2 band. Using agarose thinlayer or acetate foil electrophoresis the variant is represented only by a minimal cathodic broadening of the PGM₁ 1 band and therefore it is easily overlooked. Investigation of the propositus' family shows that the variant occurs combined with the common alleles PGM ₁ ^a1 , PGM ₁ ^a2 , and PGM ₁ ^a3 and that it has an autosomal dominant inheritance. Obviously the variant has a very low frequency.     

Genetic mapping of monoterpene composition in an interspecific eucalypt hybrid

Genetic control of foliar oil composition was investigated amongst half-sib progeny of an interspecific eucalypt hybrid. The oil was found to be largely composed of the monoterpenes, limonene, α−pinene, γ−terpinene, 1,8 cineole and p-cymene. Due to difficulties in the interpretation of the compositional data based on raw proportions, further analysis was conducted using log-ratio variables. A high degree of intercorrelation amongst log-ratios was thought to be a consequence of commonality in the biosynthetic origins of the monoterpenes. Quantitative trait locus (QTL) analysis of log-ratio variables indicated that a significant (68–81%) proportion of the variation in four out of the ten possible log-ratios were controlled by a single genomic region of the maternal Eucalyptus grandis parent. The impact of this genomic region upon oil composition was thought to be a consequence of a gene, or genes, controlling the production of limonene, as limonene was the predominant oil constituent in many hybrid individuals and was common to all log-ratios associated with the identified genomic region. Received: 20 November 1998 / Accepted: 16 June 1999     

Use of an interspecific hybrid in identifying a new allelic specificity generated at the self-incompatibility locus after inbreeding in Lycopersicon peruvianum

Summary An interspecific hybrid between Lycopersicon esculentum () and L. peruvianum has been raised by embryo rescue in vitro and used to confirm the presence of a new S-allelic specificity in its inbred L. peruvianum parent, a plant derived by enforced bud self-pollination of a self-incompatible clone with the genotype S ₁ S ₂. The inbred plant showed breeding behavior characteristic of both S ₂ and a second specificity which was not S ₁, S ₂, S ₃ or S _f. Two-dimensional gel electrophoresis of stylar proteins, however, showed only a single typical S-associated component with the M_r and pI characteristic of S₂. The alteration in specificity, therefore, was not associated with a detectable change in an S-associated protein. The F₁ interspecific hybrid showed intermediacy of vegetative and reproductive characters, relatively high fertility and full self-incompatibility. Backcrossing to L. esculentum produced only abortive seeds requiring embryo culture. Backcrosses to L. peruvianum produced a very low proportion of filled germinable seeds. Pollen of the hybrid showed superior viability and tube growth rate compared with pollen of the two parent plants.     

Asymmetric somatic hybrid plants between an interspecific Lycopersicon hybrid and Solanum melongena

Summary Asymmetric somatic hybrid plants were obtained by a modified PEG/DMSO fusion procedure between protoplasts derived from suspension cells of an interspecific tomato hybrid, Lycopersicon esculentum x L. pennellii, and mesophyll protoplasts of Solanum melongena, eggplant. The tomato hybrid was previously transformed with Agrobacterium tumefaciens and contained the kanamycin-resistance marker gene. Prior to fusion, the donor protoplasts of the tomato hybrid were gamma irradiated at 9.0 krad. Thus, non-division of irradiated tomato hybrid protoplasts coupled with kanamycin sensitivity of eggplant enabled selection of somatic cell hybrids. Forty-nine calli selected post-fusion regenerated leaf-like structures in the presence of 50 mg/l kanamycin. However, only four of the 49 calli regenerated intact shoots which rooted in the presence of 50 mg/l kanamycin and were later transferred to the greenhouse. Analysis of phosphoglucoisomerase and peroxidase isozymes, and Southern hybridization with a nuclear-specific pea 45 S ribosomal RNA gene confirmed somatic hybrid status. Cytology revealed that the four hybrid plants had chromosome numbers of 45, 60, 42 and 57, respectively; they were all sterile.     

Somatic embryogenesis and plant regeneration in an interspecific hybrid of Oryza

An embryogenic callus was obtained from immature panicle of an interspecific hybrid (Oryza sativa x O. latifolia) F₁. The medium consisted of HE salts supplemented with 2,4-D, NAA (each 2 mg/l), kinetin (3 mg/l), yeast extract (1360 mg/l) and casein hydrolyzate (300 mg/l). The callus was milk-white in colour compact and granulate in texture. Various developmental stage of embryoid, such as globular, heart-shape, scutellum-shape and mature embryoid were observed in an embryogenic callus. Plantlets were successfully regenerated from 1-month-old callus with more than 80% regenerational frequency in each subculture for 12 passages.     

Immunocytochemical localization of ubiquitin-activating enzyme in the cell nucleus

Ubiquitin-activating enzyme, "E1", is the first enzyme in the pathway leading to formation of ubiquitin-protein conjugates. We present immunocytochemical evidence that Ubiquitin-activating enzyme is concentrated in the cell nucleus. This finding points to the nucleus as the major site of action of this enzyme. Since ubiquitin itself is not similarly compartmentalized, this result suggests a high level of ubiquitin conjugate formation in the nucleus with a rapid turnover of ubiquitin conjugates.     

Inference of subgenomic origin of BACs in an interspecific hybrid sugarcane cultivar by overlapping oligonucleotide hybridizations

Sugarcane (Saccharum spp.) breeders in the early 20th century made remarkable progress in increasing yield and disease resistance by crossing Saccharum spontaneum L., a wild relative, to Saccharum officinarum L., a traditional cultivar. Modern sugarcane cultivars have approximately 71%-83% of their chromosomes originating from S. officinarum, approximately 10%-21% from S. spontaneum, and approximately 2%-13% recombinant or translocated chromosomes. In the present work, C(0)t-based cloning and sequencing (CBCS) was implemented to further explore highly repetitive DNA and to seek species-specific repeated DNA in both S. officinarum and S. spontaneum. For putatively species-specific sequences, overlappping oligonucleotide probes (overgos) were designed and hybridized to BAC filters from the interspecific hybrid sugarcane cultivar 'R570' to try to deduce parental origins of BAC clones. We inferred that 12?967 BACs putatively originated from S. officinarum and 5117 BACs from S. spontaneum. Another 1103 BACs were hybridized by both species-specific overgos, too many to account for by conventional recombination, thus suggesting ectopic recombination and (or) translocation of DNA elements. Constructing a low C(0)t library is useful to collect highly repeated DNA sequences and to search for potentially species-specific molecular markers, especially among recently diverged species. Even in the absence of repeat families that are species-specific in their entirety, the identification of localized variations within consensus sequences, coupled with the site specificity of short synthetic overgos, permits researchers to monitor species-specific or species-enriched variants.     

Cytogenetic and immunological specificity of mammalian hybrid cell lines

Karyotypes of the hybrid cell lines NS-RL-3 (TK- -sheep kidney cells and rabbit lymphocytes) and betaCR-NS (TK- -rabbit beta-cells and TK- -sheep kidney cells) were investigated. It was shown that both hybrid cell lines were characterized by presence of both sheep and rabbit chromosomes, which number and structure varies depending on the cell type and the number of passages. In some cases the aberrant chromosomes were identified. It was observed, that 40-50% of the NS-RL-3 cells survived in culture in the presence of the human blood serum, and also were identified during 7-28 days after their introduction into the organism of the animal. Thus, the partial immunological tolerance of the hybrid cell lines has been suggested.     

Production and characterization of an interspecific hybrid between leek and garlic

An interspecific hybrid between leek ( Allium ampeloprasum L.) and garlic ( Allium sativum L.) was produced by hybridization using a fertile garlic clone as a pollen donor and an ovary culture. The hybridity was confirmed by chromosome observation (2n = 3 x = 24) and randomly amplified polymorphic DNA (RAPD) analysis. The interspecific hybrid showed a vigorous growth habit, and its foliage was larger than that of the parental species. The bulb of the interspecific hybrid was heavier than that of the parents, containing an intermediate number of cloves. The hybrid could be propagated vegetatively by planting cloves. The odor compounds of garlic, which leek did not have, were detected in the volatiles of the hybrid with a certain concentration. The results of the study suggest the possibility of direct use of an interspecific hybrid between A. ampeloprasum and A. sativum as a new crop.     

Evidence of programmed cell death during microsporogenesis in an interspecific Brachiaria (Poaceae: Panicoideae: Paniceae) hybrid

Morphological changes have been investigated during plant programmed cell death (PCD) in the last few years due to the new interest in a possible apoptotic-like phenomenon existing in plants. Although PCD has been reported in several tissues and specialized cells in plants, there have been few reports of its occurrence during microsporogenesis. The present study reports a typical process of PCD during meiosis in an interspecific Brachiaria hybrid leading to male sterility. In this hybrid, some inflorescences initiated meiosis but it was arrested in zygotene/pachytene. From this stage, meiocytes underwent a severe alteration in shape showing substantial membrane blebbing; the cytoplasm became denser at the periphery; the cell nucleus entered a progressive stage of chromatin disintegration, and then the nucleolus disintegrated, and the cytoplasm condensed and shrunk. The oldest flowers of the raceme showed only the callose wall in the anthers showing obvious signs of complete sterility.     

Repression of nucleolar organizer activity in an interspecific hybrid of the genus Xenopus

Nucleolar expression in reciprocal hybrids between African frogs of the species Xenopus laevis and X. mulleri has been examined throughout ontogeny. Evidence is presented for the stagespecific regulation of nucleolar expression in these hybrids, and for a maternal effect that operates during the early development. Advantage has been taken of the nucleolar organizer deletion in X. laevis to demonstrate that the uninucleolate conditions of hybrid nuclei at certain developmental stages is the result of an allelic repression of the mulleri nucleolar organizer region by the laevis genome. Differences in nucleolar expression between the reciprocal hybrids and the parental species have been put on a quantitative basis for several selected tissues.     

Species distribution models contribute to determine the effect of climate and interspecific interactions in moving hybrid zones

Climate is a major factor delimiting species’ distributions. However, biotic interactions may also be prominent in shaping geographical ranges, especially for parapatric species forming hybrid zones. Determining the relative effect of each factor and their interaction of the contact zone location has been difficult due to the lack of broad scale environmental data. Recent developments in species distribution modelling (SDM) now allow disentangling the relative contributions of climate and species’ interactions in hybrid zones and their responses to future climate change. We investigated the moving hybrid zone between the breeding ranges of two parapatric passerines in Europe. We conducted SDMs representing the climatic conditions during the breeding season. Our results show a large mismatch between the realized and potential distributions of the two species, suggesting that interspecific interactions, not climate, account for the present location of the contact zone. The SDM scenarios show that the southerly distributed species, Hippolais polyglotta, might lose large parts of its southern distribution under climate change, but a similar gain of novel habitat along the hybrid zone seems unlikely, because interactions with the other species (H. icterina) constrain its range expansion. Thus, whenever biotic interactions limit range expansion, species may become ‘trapped’ if range loss due to climate change is faster than the movement of the contact zone. An increasing number of moving hybrid zones are being reported, but the proximate causes of movement often remain unclear. In a global context of climate change, we call for more interest in their interactions with climate change.