Proceedings of the SMBE Tri-National Young Investigators' Workshop 2005. Reconstructing the origins and dispersal of the Polynesian bottle gourd (Lagenaria siceraria).

The origin of the Polynesian bottle gourd (Lagenaria siceraria), an important crop species in prehistoric Polynesia, has remained elusive. Most recently, a South American origin has been favored as the bottle gourd could have been introduced from this continent with the sweet potato by Polynesian voyagers around A.D.

Large deletions and other gross forms of chromosome imbalance compatible with viability and fertility in the mouse.

Large deletions and other gross forms of chromosome imbalance are known in man but have rarely been found in the mouse. By screening progeny of spermatogonially irradiated male mice for a combination of runting and other phenotypic effects, we have identified animals that have large deletions comprising from 2.5-30 percent of the length of individual chromosomes, or other major chromosome changes, which are compatible with viability and fertility.

T(In1;5)44H, a complex mouse chromosomal rearrangement with a phenotypic effect.

A complex murine chromosomal rearrangement, T(In1;5)44H, was recovered after 5 Gy + 5 Gy (given 24 h apart) spermatogonial X-irradiation. T44H is a paracentric inversion of most of Chromosome (Chr) 1 (1A1-1H6), followed by splitting of the inverted segment through a reciprocal translocation with Chr 5, the latter breakpoints being in 1C2 and 5F. Linkage tests have shown that the probable order on Chr 1 is fz-ln-T44H with 2.

A candidate mouse model for Prader-Willi syndrome which shows an absence of Snrpn expression.

The best examples of imprinting in humans are provided by the Angelman and Prader-Willi syndromes (AS and PWS) which are associated with maternal and paternal 15q11-13 deletions, respectively, and also with paternal and maternal disomy 15. The region of the deletions has homology with a central part of mouse chromosome 7, incompletely tested for imprinting effects. Here, we report that maternal duplication for this region causes a murine imprinting effect which may correspond to PWS.

Adenosine deaminase, Ada, is in mouse chromosome 2H3, and is not allelic with wasted, wst.

The adenosine deaminase locus (Ada) in the mouse has been localized by in situ hybridization to band 2H3. Linkage analysis of backcross data has shown that Ada is 13.8 +/- 2.

Isolation and characterization of a cDNA clone corresponding to the mouse t-complex gene Tcp-1x.

The mouse t complex on chromosome 17 is known to harbour many genes which have an important role in spermatogenesis. One of these, Tcp-1 has been cloned and shown to code for a protein probably essential for acrosome formation. During the isolation of a cDNA for Tcp-1 two other homologous sequences were recognized and described as Tcp-1x and Tcp-1y.

Localization of the properdin factor complement locus Pfc to band A3 on the mouse X chromosome.

The locus for properdin (properdin factor complement, Pfc), a plasma glycoprotein, has been mapped to band A3 of the mouse X chromosome by in situ hybridization to metaphase spreads containing an X;2 Robertsonian translocation. The X-linkage of the locus has also been confirmed by analysis of Mus musculus x Mus spretus interspecific crosses. The XA3 localization for Pfc places it in the chromosomal segment conserved between man and mouse which is known to contain at least six other homologous loci (Cybb, Otc, Syn-1 Maoa, Araf, Timp).

Illegitimate pairing of the X and Y chromosomes in Sxr mice.

X/Y male mice carrying the sex reversal factor, Sxr, on their Y chromosomes typically produce 4 classes of progeny (recombinant X/X Sxr male male and X/Y non-Sxr male male, and non-recombinant X/X female female and X/Y Sxr male male) in equal frequencies, these deriving from obligatory crossing over between the chromatids of the X and Y during meiosis. Here we show that X/Y males that, exceptionally, carry Sxr on their X chromosome, rather than their Y, produce fewer recombinants than expected. Cytological studies confirmed that X-Y univalence is frequent (58%) at diakinesis as in X/Y Sxr males, but among those cells with X-Y bivalents only 38% showed normal X-Y pseudo-autosomal pairing.

Isolation and expression of a new mouse homeobox gene.

A homeobox-containing clone has been isolated from an adult mouse kidney cDNA library and shown by DNA sequence analysis to be a new isolate, Hox-6.1. A genomic clone containing Hox-6.

Extent of the mouse t complex and its inversions shown by in situ hybridization.

Probes for loci situated near one end of the proximal (Tcp-1) and distal (Qa-2, 3) inversions of the mouse t complex have been hybridized to chromosomes of mice with and without t complexes and with morphologically distinguishable chromosome 17s. Both the probe for Tcp-1 and that for Qa-2, 3 hybridized to clearly different positions on t and non-t chromosomes, thus making visible the extent of the two inversions. The proximal inversion extends from roughly the junction of bands A1 and A2 to band A3, and the distal inversion from band A3 to band C.

Localization of the Hprt locus by in situ hybridization and distribution of loci on the mouse X-chromosome.

The hypoxanthine phosphoribosyltransferase locus (Hprt) of the mouse has been localized by in situ hybridization to band XA6. Comparison of the distributions of known loci on the genetic and cytogenetic maps of the X-chromosome suggests some chiasma localization with a relatively high frequency of chiasmata in the F bands. In the A bands there appear to be fewer known loci than expected, but no evidence has been found so far of excessive chiasma formation.

Lack of inactivation of a mouse X-linked gene physically separated from the inactivation centre.

Previous evidence had shown that, when a mammalian X-chromosome is broken by a translocation, only one of the two X-chromosome segments shows cytological signs of X-inactivation in the form of late replication or Kanda staining. In the two mouse X-autosome translocations T(X;4)37H and T(X;11)38H the X-chromosome break is in the A1-A2 bands; in both, the shorter translocation product fails to exhibit Kanda staining. By in situ hybridization, the locus of ornithine carbamoyltransferase (OCT) was shown to be proximal to the breakpoint (i.

Clonal analysis of X-chromosome inactivation and the origin of the germ line in the mouse embryo.

Cloning of cells from peri-implantation embryos by blastocyst injection was used to investigate the time of X-chromosome inactivation in that part of the ectoderm lineage giving rise to foetal tissues of the mouse. Matings were arranged so that the two X-chromosomes of female donor cells controlled two distinct coat colours and host blastocysts were of a third colour genotype. No coat chimaeras were obtained in experiments using donor cells from the primitive ectoderm of 6th or 7th day embryos or from lactationally delayed implanting or reactivated blastocysts.

Chromosomal sex and distribution of functional germ cells in a series of chimeric mice.

An unselected series of chimeric mice were test mated to determine the parental lineage of their functional gametes. The cytological sex of each animal was established and confirmed in all cases by karyological analysis of peripheral blood lymphocytes. The parental cell lineage for each cytological sex was unequivocally established by the presence or absence of the radiation-induced translocation 15(14) (T6).

A foreign beta-globin gene in transgenic mice: integration at abnormal chromosomal positions and expression in inappropriate tissues.

We have investigated the chromosomal location, inheritance, and expression of a cloned rabbit beta-globin gene introduced into the mouse germ line by microinjection into mouse eggs. Experiments utilizing in situ hybridization to metaphase chromosomes show that the gene has integrated into one or two different chromosomal loci in each of five mouse lines analyzed. Each locus contains between three and forty copies of the foreign DNA sequence arranged in a tandem array, and the sequences at each locus are stably inherited as a single Mendelian marker.

The analysis of malignancy by cell fusion. IX. Re-examination and clarification of the cytogenetic problem.

Previous experiments with crosses between malignant and diploid mouse cells had shown that the reappearance of malignancy in hybrids in which it was initially suppressed was associated in some cases with the elimination of the chromosomes 4 derived from the diploid parent cell. In others, however, this did not appear to be so. In the present study, we have re-examined the role of the diploid chromosomes 4 in the suppression of malignancy using natural polymorphisms of the centromeric heterochromatin to identify the parental origin of the chromosomes 4 in the hybrid cells.

Meiosis in Sxr male mice: II. Further absence of cytological evidence for a Y-autosome rearrangement in sex-reversed (Sxr) mice.

If the sex-reversal factor (Sxr) in mice is represented by a segment of the Y chromosome translocated on to an autosome, this segment might be expected to show some evidence of attempted pairing with the normal Y chromosome at the first meiotic division. Our failure to find such evidence in a light microscope study of the silver-stained pachytene spermatocytes from Sxr/4, XY males further supports existing cytological information that the factor is more likely to be represented by an autosomal dominant gene mutation.