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  • 1
    Electronic Resource
    Electronic Resource
    Cytogenetic mapping of the male-determining region of Lucilia cuprina (Diptera: Calliphoridae) (1985)
    Springer
    Chromosoma 92 (1985), S. 344-350 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The Y chromosome of Lucilia cuprina was cytogenetically dissected by recovering adjacent segregation products from crosses with appropriate autosomal and Y-autosome translocations. By these means Y chromosomes lacking most of the short, long, or both arms were isolated. Only the centromeric portion of the Y chromosome was necessary for male determination and fertility, the bulk of the short and long arms having no role in sex determination. Additionally, it was shown that most of the short arm can be passed into the female line with no marked effect. These results, together with evidence from other studies, indicate that male determination in L. cuprina is centred in a discrete region near the Y chromosome centromere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327465
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  • 2
    Electronic Resource
    Electronic Resource
    C, Q and H-banding in the analysis of Y chromosome rearrangements in Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae) (1980)
    Springer
    Chromosoma 77 (1980), S. 299-308 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In Lucilia cuprina C-banding produces procentric bands on all autosomes and deep staining over most of the X and Y chromosomes which conciderably facilitates the analysis of complex Y chromosome rearrangements. The Y chromosome is generally darkly C-banded throughout while in the X chromosome a pale staining segment is found in the distal portion of the long arm. Modulation of the banding reaction results in ‘grey’ areas in both X and Y. When C-banding is compared with allocycly it is clear that not all heteropycnotic regions in the sex chromosomes C-band to the same extent. Secondary constrictions in the short arms of both X and Y chromosomes are clearly revealed by C-banding, the X satellite being polymorphic for size.— Q-banding results in a brightly fluorescing band in the short arm of structurally normal Y chromosomes. This band loses its fluorescence in some translocations, probably through a position effect. Hoechst 33258 staining does not produce any brightly fluorescing bands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00286055
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  • 3
    Electronic Resource
    Electronic Resource
    Differential sex chromosome replication and dosage compensation in polytene trichogen cells of Lucilia cuprina (Diptera: Calliphoridae) (1982)
    Springer
    Chromosoma 87 (1982), S. 21-32 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Non banded sex chromosome elements have been identified in polytene trichogen cells of Lucilia cuprina using Y-autosome translocations, C-banding and Quinacrine fluorescence. The X chromosome is an irregular granular structure while the much smaller Y chromosome has both a dense darkly stained and a loosely organised segment. The X and Y chromosomes are underreplicated in polytene cells but comparison of C- and Q-banding characteristics of sex chromosomes in diploid and polytene tissues indicates that selective replication of non C-banding material occurs in both the sex chromosomes. Brightly fluorescing material in the Y chromosome is replicated to such an extent that it consists of half the polytene element, while the C-banding material, which makes up most of the diploid X chromosome, is virtually unreplicated. Differential replication also occurs in autosomes. In XXY males, and in males carrying a duplication of the X euchromatic region, a short uniquely banded polytene chromosome is formed. It is suggested that in males carrying two doses of X euchromatin a dosage compensation mechanism operates in which genes in one copy are silenced by forming a banded polytene chromosome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00333507
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  • 4
    Electronic Resource
    Electronic Resource
    Specific recognition and differential affinity of meiotic X-Y pairing sites in Lucilia cuprina males (Diptera: Calliphoridae) (1987)
    Springer
    Chromosoma 95 (1987), S. 126-135 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Meiotic pairing of X and Y chromosomes in male Lucilia cuprina was studied by cytological observation of normal, rearranged and deficient sex chromosome karyotypes in spermatogenesis. Two X-Y pairing regions located distally in each arm of the X and Y chromosomes were defined. Contrasting with findings in Drosophila melanogaster, these pairing regions show specific recognition of their partners. By studying rearranged sex chromosomes short arm pairing was localised to their distal ends, closely associated with secondary constrictions containing nucleolar organisers in both sex chromosomes. Short arm pairing is very tight and not greatly disrupted by chromosome rearrangement, deficiency for the Y chromosome long arm or the presence of supernumerary X chromosomes. The pairing region of the long arms could not be precisely localised but probably also occurs at their distal ends. Pairing between the long arm sites is much weaker and is easily disrupted by chromosome rearrangement, failing completely in flies deficient for the Y chromosome short arm. No cytologically visible pairing was seen between X chromosomes and the remainder of the Y. In males with an extra X chromosome, the ends of both X chromosomes pair to form multivalents with normal and rearranged Y chromosomes provided the Y short arm is present, otherwise an independent X chromosome bivalent is formed. The mechanism of pairing in male Lucilia sex chromosomes thus seems to depend on specific loci of distinctive structure within the X and Y heterochromatin. Comparison of cytological and genetic data shows that increasing cytological pairing failure is matched by higher genetic X-Y nondisjunction but that the former occurs at much higher levels. In some karyotypes cytologically observed X-Y pairing failure is not matched by high frequencies of nondisjunction presumably because weak pairing associations are disrupted during slide preparation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00332185
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  • 5
    Electronic Resource
    Electronic Resource
    Cytogenetic studies of Lucilia cuprina dorsalis R.-D. (Diptera: Calliphoridae) (1980)
    Springer
    Chromosoma 81 (1980), S. 151-168 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Standard photographic maps of the trichogen cell polytene chromosomes are presented. Polytene chromosome locations of 39 mutations have been determined by genetic mapping of autosomal duplications, inversions and translocations. Homologies between the polytene chromosomes of L. cuprina, other Calliphoridae, and Sarcophagidae are noted; genetic linkage groups may have been conserved largely intact during the evolution of the higher Diptera.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00285946
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  • 6
    Electronic Resource
    Electronic Resource
    Characterization and chromosomal distribution of a tandemly repeated DNA sequence from the Australian sheep blowfly, Lucilia cuprina (1992)
    Springer
    Chromosoma 101 (1992), S. 358-364 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In the course of making a Lucilia cuprina genomic DNA library, a ladder of bands was seen in partial Sau3A digests. Complete digestion reduced this ladder to predominantly monomer units of approximately 190 bp. Nine independently isolated copies of this repeat were cloned and sequenced. Only two of these isolates are identical in sequence, the most divergent being 71% homologous. This satellite DNA occurs in all three wildtype strains tested, and, for the single case examined, in the embryonic, larval, pupal, and adult DNA. It represents approximately 3%–4% of the genome. Data obtained from in situ chromosome hybridizations indicate that this sequence is concentrated around the centromeric regions of the autosomes and over most of the sex chromosomes. Labelling is much stronger in mitotic compared with polytene chromosomes showing directly that this centromeric satellite DNA is grossly under-replicated during polytenization. This under-replication is even more pronounced on the sex chromosomes compared with the autosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00346015
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  • 7
    Electronic Resource
    Electronic Resource
    Polytene chromosomes in pupal and adult blackflies (Diptera: Simuliidae) (1976)
    Springer
    Chromosoma 57 (1976), S. 387-396 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A number of pupal and adult tissues of eight Australian blackfly species representing three genera, Austrosimulium, Cnephia and Simulium, were examined for the presence of polytene chromosomes. Banded polytene chromosomes were found in malpighian tubules, hind gut, fat body, and ovary, but only those from the malpighian tubules of female adults and pupae were of good quality. A detailed comparison of polytene chromosomes from larval salivary glands and adult malpighian tubules was made in S. ornatipes and, to a limited extent, in S. melatum. The banding patterns of chromosomes from both tissues were found to be identical with minor differences in puffing patterns in S. ornatipes and chromocenter characteristics in S. melatum. A survey of the remaining six species shows five of them to have malpighian chromosomes suitable for detailed cytological analysis. Simultaneous studies of larval, pupal and adult polytene chromosome systems offer a novel approach to the analysis of population problems in blackflies. The ability to recognise sibling species in adults also has potential practical significance in efforts to control vectors of onchocerciasis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00332162
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  • 8
    Electronic Resource
    Electronic Resource
    Cytogenetics and evolution of Simulium ornatipes skuse (Diptera:Simuliidae) I. Sibling speciation (1977)
    Springer
    Chromosoma 64 (1977), S. 37-65 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Larval populations of the morphologically distinct species Simulium ornatipes and S. neornatipes and a subspecies of the former, S. ornatipes norfolkense, were analysed using polytene chromosome cytology. Fixed inversion differences, distinct differentiated sex chromosomes and unique arrays of chromosomal polymorphisms reveal two sibling species, S. ornatipes A and B, within S. ornatipes, and two, S. neornatipes 1 and 2, within S. neornatipes. Chromosomally S. ornatipes norfolkense is similar to S. ornatipes A. An unprecedented level of shared inversion polymorphism is shown by S. ornatipes A and B indicating a very close relationship between them. While it may be postulated that such a situation has arisen by independent origin of the shared inversions within each species, or by introgression of these rearrangements between the two species, it is concluded that the shared polymorphisms in fact originate from a common ancestor. Within the four chromosomally defined species, differentiated sex chromosome systems occur which may involve any of the three chromosome pairs. Simulium ornatipes A is particularly interesting because there are indications that it may be polymorphic for differentiated sex chromosomes on two different elements and that it may also share a sex chromosome marker with S. ornatipes B, a unique situation in the Simuliidae. The evolution of sex chromosome systems in the four species is compared with that of other Simulids and its intimate connection with speciation emphasised. Finally the data on fixed inversions, differentiated sex chromosomes and shared polymorphisms is used to construct a phylogeny of the four species outlining their patterns of speciation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292888
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  • 9
    Electronic Resource
    Electronic Resource
    Conservation of nucleolar structure in polytene tissues of Ceratitis capitata (Diptera: Tephritidae) (1989)
    Springer
    Chromosoma 98 (1989), S. 443-449 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292790
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  • 10
    Electronic Resource
    Electronic Resource
    Homozygous-viable pericentric inversions for genetic control of Lucilia Cuprina (1991)
    Springer
    Theoretical and applied genetics 82 (1991), S. 681-689 
    Details
    ISSN: 1432-2242
    Keywords: Genetic control ; Genetic sexing ; Pericentric inversions ; Lucilia cuprina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The isolation of homozygous-viable pericentric inversions for inclusion in field-female killing (FK) systems in Lucilia cuprina is described. From 7,236 irradiated chromosomes screened, 16 pericentric inversions were isolated. Four of these were viable as homozygotes. One of these, In (3LR) 14, possesses the properties required for inclusion in FK systems (tight linkage of one inversion break-point to the white-eye gene and substantial genetic exchange within the inversion in heterozygous females).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227311
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