T-cell receptor-specific monoclonal antibodies against a V β 11-positive mouse T-cell clone

Two monoclonal antibodies specific for the mouse T-cell receptor (Tcr) have been established by immunization with a V 11⁺ T-cell clone, clone C6. One is a rat antibody, KT11 (IgG2b, k), specific for the V chain of C6, V 11. This was demonstrated by the fact that the strain distribution pattern of KT11⁺ cells was similar to that of V 5, 8, 9, 11, 12, and 13 and that the gene that encodes the molecule detected by KT11 was closely linked to V 8 in (B10 × SJL)F₁ × SJL backcross mice. Furthermore, V of C6 has been cloned from a gt10 cDNA library and was demonstrated to be identical to the V 11 published sequences. All strains of mice that do not express major histocompatibility complex class II E molecules had higher numbers of KT11^– cells than E⁺ strains. The KT11⁺ population in A strain mice and its H-2 congenic strains, however, was not affected by the presence or absence of E molecules. The other is a mouse antibody, KTL2 (IgM), specific for the idiotope of the Tcr expressed on the clone C6. Both antibodies were mitogenic and induced cytotoxicity. Expression of epitopes detected by KT11 or KTL2 was down-modulated by a T3-specific antibody 145-2C11.     

Roles of clone–clone interactions in building reef frameworks: principles and examples

In living and fossil reefs, rapid upward clone growth provides positive topographic relief; the skeletal framework provides rigidity. Clonal organisms have been the chief frame-builders during most of the Phanerozoic; large clone size, growth habit, growth form, and arrangement of these clones in the framework result from rapid growth rates. Dense skeletal packing enhances rigidity and results in live–live interactions between juxtaposed clones. These interactions are both heterospecific and conspecific; the former mostly involve spatial competition whereas the latter involve clone fusion, self-overgrowth, and fission. We describe three types of fusion: (a) inter-clone fusion of two or more clones, each from a separate propagule; (b) intra-clone fusion of parts of the same clone having its origin from a single propagule; it includes recovery from partial clone degradation and self-overgrowth; (c) quasi-fusion between a live bud/polyp/zooid and a dead part (stem; branch) of the same or a different clone, i.e., a live-dead association.     

When does a clone deserve a name? A perspective on bacterial species based on population genetics.

Molecular population-genetic analysis has revealed that for several human diseases, including tuberculosis, plague and shigellosis, the generally accepted taxonomic status of the organisms involved does not fit the usually accepted genus or species criteria. This raises the question of what species concept to apply to bacteria. We suggest that the species definition in bacteria should be based on analysis of sequence variation in housekeeping genes, and also that the "clone" be given official status in bacterial nomenclature. This will allow demotion of the species or genus status of several traditionally recognized human pathogens, but retention of current names of anomalous species and genera as clone names.     

Preliminary experiments on resource competition between a migrating and a non-migrating clone of the hybrid D. galeata×hyalina

Competition experiments between two clones of thehybrid D. galeata × hyalina differing invertical migration behaviour were carried out in thelaboratory, in a set-up which separated the clonesspatially. The influence of fish kairomones,artificial predation and the imitation of dielvertical migration circumstances were investigated. Inthe presence of fish kairomones, the non-migratingclone outnumbered the migrating one. The introductionof artificial predation reduced this effect in such away that the migrating clone had a competitiveadvantage over the non-migrating clone. It wasconcluded that competition results do not contradictlife history studies performed with the same twoclones, since the presence of fish kairomones enhancesthe reproduction of the non-migrating clone more thanthat of the migrating one.     

Yellow–green color polymorphism in males of a pea aphid clone and its genetic pattern

Although most aphid species living on leaves have a green body color, little is known regarding the biosynthetic pathways of green pigments. We found that a clone of the pea aphid, Acyrthosiphon pisum (Harris) produced both green- and yellow-colored males. The females of this clone were green in color, while 8.4% of the males produced were yellow. To date, yellow body color has been reported only in a single mutant clone in A. pisum. To explore the genetic pattern of yellow body color, green or yellow males were mated with green females of the same clone. The hatchability of the eggs sired by yellow males (26.2%) was less than half that of the eggs sired by green males (79.0%). The hatched foundresses of both groups were all green, with no yellow foundresses. Because aphids have an XX-XO sex determination system, color polymorphism in males suggests that male body color may be governed by an X-linked locus. If females possess heterozygosity at the putative locus, they can produce alternative phenotypes in males. The small proportion of yellow males and absence of yellow foundresses imply that the allele responsible for yellow body color has a deleterious effect. The present study suggests that this clone could be used to elucidate the biosynthetic pathways and underlying genetics of green pigments in aphids.     

How accurate is the phenotype? – An analysis of developmental noise in a cotton aphid clone

Background  

The accuracy by which phenotype can be reproduced by genotype potentially is important in determining the stability, environmental sensitivity, and evolvability of morphology and other phenotypic traits. Because two sides of an individual represent independent development of the phenotype under identical genetic and environmental conditions, average body asymmetry (or "fluctuating asymmetry") can estimate the developmental instability of the population. The component of developmental instability not explained by intrapopulational differences in gene or environment (or their interaction) can be further defined as internal developmental noise. Surprisingly, developmental noise remains largely unexplored despite its potential influence on our interpretations of developmental stability, canalization, and evolvability. Proponents of fluctuating asymmetry as a bioindicator of environmental or genetic stress, often make the assumption that developmental noise is minimal and, therefore, that phenotype can respond sensitively to the environment. However, biologists still have not measured whether developmental noise actually comprises a significant fraction of the overall environmental response of fluctuating asymmetry observed within a population.     

A satellite-like sequence,representing a “clone gap” in the human genome,was likely involved in the seeding of a novel centromere in macaque

Although the human genome sequence is generally considered “finished”, the latest assembly (NCBI Build 36.1) still presents a number of gaps. Some of them are defined as “clone gaps” because they separate neighboring contigs. Evolutionary new centromeres are centromeres that repositioned along the chromosome, without marker order variation, during evolution. We have found that one human “clone gap” at 18q21.2 corresponds to an evolutionary new centromere in Old World Monkeys (OWM). The partially sequenced gap revealed a satellite-like structure. DNA stretches of the same satellite were found in the macaque (flanking the chromosome 18 centromere) and in the marmoset (New World Monkey), which was used as an outgroup. These findings strongly suggested that the repeat was present at the time of novel centromere seeding in OWM ancestor. We have provided, therefore, the first instance of a specific sequence hypothesized to have played a role in triggering the emergence of an evolutionary new centromere. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

High-yielding repetitive somatic embryogenesis and plant recovery in a selected tea clone, ‘TRI-2025’, by temporary immersion

 Methods for improving the efficiency of repetitive somatic embryogenesis and plant recovery from somatic embryos of clonal tea, TRI 2025 [Camellia sinensis (L.) O. Kuntze] were investigated by optimising the immersion frequencies of the explants using a modified temporary immersion system (TIS). The relative efficiencies of three conventional methods for multiplying embryos were compared with the temporary immersion method. The highest rate of multiplication of secondary embryos (24-fold) was achieved using the TIS. By controlling the immersion cycles, we achieved more consistent, synchronised multiplication and embryo development with a high level of plant recovery. A one-step computer-programmed immersion protocol based on a single, simple medium with no growth regulators was developed, enabling multiplication, maturation, germination and plant recovery within 17 weeks. Plantlets recovered through this method were hardy, with 2- to 5-cm-long shoots containing a minimum of 2–4 lush green leaves and a well-formed taproot. Callus formation, hyperhydricity and other developmental abnormalities were not observed at any stage in the process. Plantlets produced using this method were successfully acclimatised to glasshouse conditions. This protocol avoids culture transfers, and thus minimises the risk of contamination and reduces labour costs. This technique could have significant commercial implications in tea propagation as it has the potential for large-scale production with considerably reduced production costs. Received: 28 June 1999 / Accepted: 20 April 2000     

Spatial variation in local pollen flow and mating success in a Picea abies clone archive and their implications for a novel ��breeding without breeding�� strategy

Currently, Norway spruce (Picea abies) breeding in Sweden is based on crosses between the best clones followed by clonal testing of the progenies to select for the long-term breeding population. An alternative breeding strategy called “Breeding without Breeding” (BwB) is proposed, which, in principle, relies on the DNA marker-based pedigree reconstruction from wind-pollinated progenies instead of controlled crosses. To test whether the pedigree structure could be established from progenies of clonal trials, we investigated the spatial pattern of local pollen flow and paternity assignment in a clone archive of Norway spruce. The results showed that 42% of the progeny can be assigned to fathers within 30-m distance with high confidence. Effective pollen dispersal decreased rapidly with distance and followed exponential distribution on local scale. The extent of close-neighbor (within 6 m) mating ranged from 0% to 48% among grafts with an average of 13%. Distance explained 25% deviance in mating success, and other factors such as phenology and spatial configuration of the clones should have contributed the rest. The success of parentage assignment in clone archive opens up the possibility to apply BwB in clonal trials of species that are easy to propagate vegetatively. This procedure could substantially shorten the breeding cycle and still give similar gain per year as the conventional breeding.     

Idiotypic analysis of a B cell clone with anti-intermediate filament specificity in a patient with Sj?gren's syndrome: involvement of five subpopulations producing different immunoglobulin isotypes

An IgM paraprotein from patient LP with Sj?gren's syndrome exhibited an antibody activity to intermediate filaments (IMF) of cells from all vertebrates examined, and appeared to recognize several classes of IMF (i.e., vimentin, desmin, and keratin). A mouse monoclonal anti-idiotype (Id) antibody, K4A, was prepared against the IgMk (LP) and used as a specific probe in two-color immunofluorescence to examine the extent of clonal involvement in the patient's blood and bone marrow mononuclear cells (MNC). Twenty to 30% of MNC in her blood samples were IgMk+ plasmablasts with morphologic similarity to Waldenstr?m's macroglobulinemia cells. IgG+ and IgA+ plasmablasts were demonstrated in lower frequencies (approximately 2%). Almost all of the IgM+ cells and approximately 80% of the IgG+ cells and IgA+ cells in the blood were reactive with the K4A anti-Id antibody. Immunoglobulin (Ig) subclass analysis revealed that the K4A Id was expressed by IgG1+, IgG3+, IgA1+ and IgA2+ plasmablasts. Similar observations were obtained with bone marrow samples, although the proportion of Id+ cells among IgG+ or IgA+ cells was lower in marrow than in blood. IgG and IgA fractions isolated from the patient's serum were also shown to contain anti-IMF activity. Ig biosynthetic analysis of blood MNC revealed that the K4A anti-Id antibody precipitated not only IgM but also IgG and IgA. Because cells simultaneously producing two different Ig isotypes were not detected, these results indicate the presence of five separate subpopulations of the K4A Id+ neoplastic clone. The data thus suggest the occurrence of a neoplastic or pre-neoplastic transformation event before the switching of Ig heavy chain isotypes, and imply a role for the IMF antigen in the exaggerated proliferation and differentiation along five of the nine potential intraclonal pathways.     

Why clone flies? Using cloned Drosophila to monitor epigenetic defects

Since the birth of the first cloned sheep in 1996, advances in nuclear transplantation have led to both the creation of genetically tailored stem cells and the generation of a number of cloned organisms. The list of cloned animals reared to adulthood currently includes the frog, sheep, mouse, cow, goat, pig, rabbit, cat, zebrafish, mule, horse, rat and dog. The addition of Drosophila to this elite bestiary of cloned animals has prompted the question - why clone flies? Organisms generated by nuclear transplantation suffer from a high rate of associated defects, and many of these defects appear to be related to aberrant genomic imprinting. Imprinted gene expression also appears to be compromised in Drosophila clones. Proper imprinted gene regulation relies on a suite of highly conserved chromatin-modifying genes first identified in Drosophila. Thus, Drosophila can potentially be used to study epigenetic dysfunction in cloned animals and to screen for genetic and epigenetic conditions that promote the production of healthy clones.     

Apparent “in situ” clone of cytogenetically marked ataxia-telangiectasia lymphocytes

Summary Six adjacent metaphases, each with the same cytogenetic aberration of a group D chromosome, most probably a No. 14, were observed in a field of a slide from a 96-hour culture of lymphocytes from an individual with ataxia-telangiectasia (AT). None of the 304 orther metaphases examined from this or other simultaneous cultures of this individual showed such an aberration. It seems most likely that an in situ marked clone has been observed and this supports interpretation of consistent cytogenetic abnormalities in those with AT as having clonal origin. The method of slide preparation employed which involves placing, rather than dropping, the cell suspension on the slide may facilitate detection of in situ clones.     

Establishment of a variant cell clone growing at 41° C from embryonic rat and tupaia (tree shrew) fibroblast cells

Summary Rat and tupaia 41° C temperature variant cell clones were derived from parental embryonic cells, cloned and established in tissue cultures. Both variant cell clones grew permanently at 41° C. The morphology of these cell clones was altered in comparison to the original fibroblast cell clones. The cell biological characterization of the rat and tupaia 41° C temperature variant cell clones showed that both cell clones were stable. After abolishing the selection pressure (incubation at 41° C) for more than 10 further cell passages by incubation at 37°C and then raising the temperature again to 41° C, neither of the cell clones lost their newly acquired property of prowing at 41° C. This fact demonstrates that the newly acquired property is certain to be genetically manifest in both cell clones. The modal number of chromosomes of the rat 41° C temperature variant cell clone was increased, and the case of the tupaia variant cell clone, bimodality was observed. The plating efficiency of both cell clones did not rise significantly in comparison to the parental cells. Neither of the 41° C temperature variant cell clones grew in semi-solid medium. This work was partially supported by the Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 136.