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Notes: Riassunto Osservazioni su femmine diForficula auricularia L. indicano che esse possiedono un solo cariotipo formato da 22 autosomi e da 2 cromosomiX. Sulla base di questo studio, suggeriamo che i maschi con 3 cromosomi sessuali sono del tipoXYY, e nonXXY come precedentemente ritenuto da varii autori. Ci sono maschiXY 1t, XY2, XY2Y2 e mosaiciXY 2/XY2Y2 nella popolazione. Inoltre viene dimostrato che solamente il più grande dei due cromosomi Y, che caratterizzano questa specie, viene accumulato nei maschi con un meccanismo multiple di cromosomi sessuali.

Notes: Abstract In Chortoicetes terminifera, G-banding, produced by the trypsin treatment of air-dried slides followed by Giemsa staining, leads to light staining gaps at the secondary constrictions on autosomal pair 6 and regions proximal to the centromere on the long arms of pair 4. The variable short arms of two of the three smallest pairs were usually flared and lightly stained after treatment. In contrast to the relatively minor response of the normal chromosome set to G-banding, the large supernumerary chromosomes of C. terminifera show a spectacular series of dark bands alternating with lightly stained gaps. Two G-band variants of the B-chromosome were found in a laboratory stock. These patterns of G-banding are discernable both at mitosis in adults and embryos of both sexes and at all stages of male meiosis. Some regions which are gaps after G-banding appear as dark bands after C-banding. Consequently the supernumerary chromosome is mainly darkly stained with C-banding. In addition the centromeres and some telomeres are C-banded along with narrow interstitial bands and polymorphic heterochromatic blocks. — C-banding was not always successful, the technique often yields a mixture of G- and C-banding. The disparity of banding between the normal complement and the B-chromosome implies that whatever the source of origin of the B it has undergone spectacular changes in organisation since its origin.

Notes: Abstract The karyotypes of Warramaba virgo and the two bisexual species which gave rise to it, by hybridization, have been studied by the C- and G-banding techniques. W. virgo consists of a number of clones which differ by a limited number of inversions, translocations and fusions and also in C-banding pattern. In general, each local population consists of a single clone, although instances are known where two clones exist at the same locality. A total of fifteen cytological clones are here recognised and described. Some of these are known from single localities, while others have been found at several collecting sites in the same general area. The differences between them in banding pattern are relatively minor, i.e. the architecture of the karyotype has been highly conserved. A total of 50 C-bands have been recognised in W. virgo, but some of these are only present in a single clone and most clones have 39–40 bands. Most of these are centromeric or interstitial; a few are terminal (telomeric) in the short arms. There are three types of bands, dark-staining centromeric ones, intermediate ones that are somewhat less densely staining, and lighter ones that appear “grey” even after successful C-banding. The C-banding pattern of W. virgo provides additional evidence for its origin by hybridization between the bisexual species “P196” and “P169”. It is possible that W. virgo arose only “once” (i.e. from one or more matings between P196 and P169 individuals in the same deme, within a few generations). However, two clones (Zanthus and Boulder), which are themselves closely similar, differ so much in banding pattern from all others that they may have arisen independently.

Notes: Abstract Two mosaic sibling embryos of the Australian plague locust, Chortoicetes terminifera are reported with haploid and diploid cell lines in widely differing proportions. One small chromosome pair involved in the two cases has alternative morphology and a B-chromosome is present in one. In addition, G-banding identifies two medium-sized chromosome pairs and alternative states of a second small pair. Using these markers it is clear that both diploid cell lines are homozygous for the chromosomes of the corresponding haploid line. These embryos have thus developed by accidental parthenogenesis from haploid cells, some of which were duplicated by endomitosis after development began.

Notes: Abstract Triploid hybrids have been obtained by crossing individuals of the diploid Warramaba virgo with males of two undescribed related species of Warramaba, “P169” (neo-XY) and “P196” (X1X2Y). In both cases, offspring which receive a Y-chromosome from the father are males, while those that receive a neo-X from P169 or an X1 and an X2 from P196 are females. The triploids can be distinguished from diploids, even in the earliest nymphal instars, by the larger size of their eye facets. Their gonads are undeveloped and abnormal so that they are mostly sterile (the males absolutely so). Nevertheless, in the case of female hybrids (both the ones between virgo and P169 and those between virgo and P196) a few oocytes do develop and it was possible to obtain a further generation of hybrids by parthenogenesis. These, which are all female, and have karyotypes identical to those of their mothers, are derived from eggs which have undergone the virgo type of meiosis, with a premeiotic doubling of the chromosome number, followed by synapsis restricted to sister chromosomes. — Some diploid hybrids have also been obtained between the bisexual species P169 (♀) and P196 (♂). In this case the male offspring died in the embryonic stage or immediately after hatching. Female hybrids, on the other hand, were viable but had under-developed ovaries, so that they only laid very few eggs. Some of the latter developed into embryos with a karyotype identical to that of the mother, but the meiosis of these eggs has not yet been studied, so that it is not known whether it is of the virgo type. These hybridization experiments support the hypothesis that virgo originated as a hybrid between P196 and P169. — A single male hybrid between Warramaba picta (♀) and P169 (♂) was obtained; it had active spermatogenesis, but many meiotic abnormalities.

Notes: Abstract An undescribed bisexual grasshopper species closely related to the all-female parthenogenetic Moraba virgo has an X1X2Y sex chromosome mechanism which incorporates 7 chromosomes of the ancestral karyotype (the original X and three pairs of autosomes). Apparently three separate chromosomal fusions have occurred, one of these being a tandem fusion followed by a crossover which ‘stabilized’ it in the sex chromosome system. M. virgo probably arose from an ancestor which had X1X2Y males but lacked the tandem fusion present in the new species, the females of virgo having the constitution X1X1X2O.

Notes: Abstract The distribution of constitutive heterochromatin has been investigated in four chromosomal races of the grasshopper Caledia captiva (2n= 23 ♂/24 ♀) by the C-banding technique. Each of the four races was found to have a distinctive banding pattern which is associated with the inter-racial differences in chromosomal rearrangements. — The “Ancestral” race has a telocentric chromosome complement with large procentric C-bands which are structurally double on six pairs of chromosomes. The centromeres are unstained. — The “General Purpose” race has a C-banding pattern very similar to that seen in other Acridine grasshoppers with the majority of its chromosomes showing a centromeric localisation of the bands. — The two southern races, which show a complex polymorphism for presumed pericentric inversions on all twelve chromosomes, also show an unusually high level of interstitial and terminal C-bands. The different locations and numbers of these bands allow unambiguous identification of all the chromosome pairs within the complement. — In two cases, there is good evidence to indicate that a C-band redistribution between acrocentric and metacentric chromosomes has occurred by pericentric inversion. Furthermore, C-band variation on the long arm of the metacentric X-chromosome indicates the presence of a large paracentric inversion. This double inversion system has involved over 95% of the X-chromosome. — The interstitial and terminal C-bands probably have not resulted from heterochromatin movement within the complement but, more likely, have arisen by saltatory duplication of pre-existing sequences on the chromosome. — A new nomenclature system for banded chromosomes is proposed which allows most kinds of chromosomal restructuring and rearrangement to be adequately enumerated.

Notes: Abstract In Chortoicetes terminifera 45 independently-occurring B-chromosomes were tested and 23 distinct banding variants were detected with either G- or C-banding; six types were found more than once. In particular the Type I banding morph was detected 12 times indicating that individuals carrying this type may be under a different regime of selection compared with individuals bearing other types of banding morph; or the Type I may be subjected to a higher rate of meiotic drive in either or both sexes than other types. Also the Type I appeared to be obviously related to four other banding morphs whereas most types were not obviously related to any other banding morphs, but a few were similar in banding pattern to one or two other types. Three types of B-chromosomes were found in three or more different populations. A relatively high frequency of the Type I banding morph was found in one population, which was probably mainly composed of non-migratory individuals, and also in a laboratory-raised population. The most likely mechanisms for small changes in the banding sequence of the B-chromosomes are three-break insertions which are often indistinguishable from inversions. Rearrangements which add or delete bands, or sequences of bands, to or from B-chromosomes are probably the result of exchanges which are now known to take place in rare individuals with two B-chromosomes. The most distal region of all the banding morphs of the B-chromosome in C. terminifera, plus a short interstitial region in some types, is not late-replicating and has the banding characteristics of euchromatin. The rest of the chromatin of the B-chromosomes is heterochromatic and is the latest replicating heterochromatin in the whole genome. It consists of G-bands, which are also deeply stained with C-banding, and alternating G-interbands, which in turn are stained “grey” with C-banding. Both of these staining combinations are seen in heterochromatin of the normal complement. The heterochromatin of the B-chromosomes is condensed throughout 1st meiotic prophase in the male and in all somatic interphase nuclei where it can be quickly detected using the G-banding technique. The B-chromosome has a relatively constant, acrocentric morphology with a tendency to increase of length of the long arm as band numbers increase. Isochromosomes of the long arm have been seen only in laboratoryraised embryos. From egg pods with significantly fewer than expected B-chromosomes it is strongly suggested that more than one male may fertilize the eggs in a single pod.

Notes: Abstract Nucleolar structure was studied in mitotic and three polytene tissues of the Mediterranean fruit fly, Ceratitis capitata using in situ hybridization with a tritium-labelled rDNA probe and silver staining. In mitotic metaphase chromosomes nucleolar organiser regions were localised in the short arms of both sex chromosomes. In polytene nuclei of trichogen cells, salivary glands and fat body rDNA was detected within nucleoli. Nucleoli in these tissues have a similar structure with rDNA labelling concentrated in a central core. Silver staining resulted in very heavy staining of polytene nucleoli and interphase nucleoli in diploid cells. Silver staining of nucleolar organisers in metaphase chromosomes is weak or absent although the X chromosome has numerous dark silver bands in other locations. The results suggest that nucleolar structure is conserved in polytene tissues contrasting with the variability of autosomal banding patterns and sex chromosome structure. They also indicate that silver staining is not necessarily specific for nucleolar regions.

Notes: Summary A neonate with clinical features of the 11q23 deletion syndrome was apparently mosaic with the dominant cell line showing deletion of the chromosomal segment 11q23.3 to 11qter. The presence of a few lymphocytes with a normal karyotype indicates post-zygotic deletion of chromosome 11. The mother and brother of the propositus show folate-sensitive fragility at band 11q23.3. This case indicates in vivo deletion at a folate-sensitive fragile site.