Subject(s)
Blister/genetics , DNA/genetics , Epidermolysis Bullosa/genetics , Membrane Proteins/genetics , Mutation , Neoplasm Proteins/genetics , Periodontal Diseases/genetics , Photosensitivity Disorders/genetics , Skin/pathology , Adolescent , Blister/diagnosis , Blister/metabolism , Child , Child, Preschool , DNA Mutational Analysis , Epidermolysis Bullosa/diagnosis , Epidermolysis Bullosa/metabolism , Humans , India , Male , Membrane Proteins/metabolism , Neoplasm Proteins/metabolism , Periodontal Diseases/diagnosis , Periodontal Diseases/metabolism , Photosensitivity Disorders/diagnosis , Photosensitivity Disorders/metabolism , Polymerase Chain Reaction , Skin/metabolismABSTRACT
A cosmid/bacterial artificial chromosome (BAC) contiguous (contig) map of human chromosome (HSA) 19p13.3 has been constructed, and over 50 genes have been localized to the contig. Genes and anonymous ESTs from approximately 4000 kb of human 19p13.3 were placed on the central mouse chromosome 10 map by genetic mapping and pulsed-field gel electrophoresis (PFGE) analysis. A region of approximately 2500 kb of HSA 19p13.3 is collinear to mouse chromosome (MMU) 10. In contrast, the adjacent approximately 1200 kb are inverted. Two genes are located in a 50-kb region after the inversion on MMU 10, followed by a region of homology to mouse chromosome 17. The synteny breakpoint and one of the inversion breakpoints has been localized to sequenced regions in human <5 kb in size. Both breakpoints are rich in simple tandem repeats, including (TCTG)n, (CT)n, and (GTCTCT)n, suggesting that simple repeat sequences may be involved in chromosome breaks during evolution. The overall size of the region in mouse is smaller, although no large regions are missing. Comparing the physical maps to the genetic maps showed that in contrast to the higher-than-average rate of genetic recombination in gene-rich telomeric region on HSA 19p13.3, the average rate of recombination is lower than expected in the homologous mouse region. This might indicate that a hot spot of recombination may have been lost in mouse or gained in human during evolution, or that the position of sequences along the chromosome (telomeric compared to the middle of a chromosome) is important for recombination rates.
Subject(s)
Chromosome Breakage/genetics , Chromosomes, Human, Pair 19/genetics , Evolution, Molecular , Physical Chromosome Mapping , Animals , Chromosome Inversion , Chromosomes, Bacterial/genetics , Cosmids/genetics , Electrophoresis, Gel, Pulsed-Field , Female , Genetic Markers/genetics , Humans , Male , Mice , Mice, Inbred C57BL , Mice, Neurologic Mutants , Repetitive Sequences, Nucleic Acid , Sequence Homology, Nucleic AcidABSTRACT
The mouse mutant mocha, a model for the Hermansky-Pudlak storage pool deficiency syndrome, is characterized by defective platelets, coat and eye color dilution, lysosomal abnormalities, inner ear degeneration, and neurological deficits. Here, we show that mocha is a null allele of the delta subunit of the adaptor-like protein complex AP-3, which is associated with coated vesicles budding from the trans-Golgi network, and that AP-3 is missing in mocha tissues. In mocha brain, the ZnT-3 transporter is reduced, resulting in a lack of zinc-associated Timm historeactivity in hippocampal mossy fibers. Our results demonstrate that the AP-3 complex is responsible for cargo selection to lysosome-related organelles such as melanosomes and platelet dense granules as well as to neurotransmitter vesicles.
Subject(s)
Blood Platelets/metabolism , Endosomes/metabolism , Melanocytes/metabolism , Mutation/genetics , Platelet Storage Pool Deficiency/genetics , Synaptic Vesicles/metabolism , Transcription Factors/genetics , Adaptor Protein Complex 3 , Adaptor Protein Complex beta Subunits , Alleles , Animals , Base Sequence , Biological Transport/physiology , Central Nervous System/metabolism , Chromosome Mapping , Gene Rearrangement , Mice , Mice, Inbred C57BL , Molecular Sequence Data , Platelet Storage Pool Deficiency/metabolism , RNA, Messenger/metabolism , Transcription, Genetic , Zinc/metabolismABSTRACT
A clone showing female-specific expression was identified from an embryonic cDNA library of a mealybug, Planococcus lilacinus. In Southern blots this clone (P7) showed hybridization to genomic DNA of females, but not to that of males. However, P7 showed no hybridization to nuclei of either sex, raising the possibility that it was extrachromosomal in origin. In sectioned adult females P7 hybridized to an abdominal organ called the mycetome. The mycetome is formed by mycetocytes, which are polyploid cells originating from the polar bodies and cleavage nuclei that harbour maternally transmitted, intracellular symbionts. Electron microscopy confirmed the presence of symbionts within the mycetocytes. Sequence analysis showed that P7 is a 16S rRNA gene, confirming its prokaryotic origin. P7 transcripts are localized to one pole in young embryos but are found in the pole as well as in the germ band during later stages of development. P7 expression is detectable in young embryos of both sexes but the absence of P7 in third instar and adult males suggests that this gene, and hence the endosymbionts, are subject to sex-specific elimination.
Subject(s)
Gene Expression Regulation, Developmental , Insecta/genetics , RNA, Messenger/genetics , RNA, Ribosomal, 16S/genetics , Animals , Base Sequence , Female , In Situ Hybridization, Fluorescence , Insecta/embryology , Insecta/parasitology , Larva/ultrastructure , Male , Microscopy, Electron , Molecular Sequence Data , Sequence Homology, Nucleic AcidABSTRACT
In mealybugs, chromatin condensation is related to both genomic imprinting and sex determination. The paternal chromosomal complement is condensed and genetically inactive in sons but not in daughters. During a study of chromatin organization in Planococcus lilacinus, digestion with micrococcal nuclease showed that 3% to 5% of the male genome is resistant to the enzyme. This Nuclease Resistant Chromatin (NRC) apparently has a nucleosomal organization. Southern hybridization of genomic DNA suggests that NRC sequences are present in both sexes and occur throughout the genome. Cloned NRC DNA is A+T-rich with stretches of adenines similar to those present in mouse alpha-satellite sequences. NRC DNA also contains sequence motifs that are typically associated with the nuclear matrix. Salt-fractionation experiments showed that NRC sequences are matrix associated. These observations are discussed in relation to the unusual cytological features of mealybug chromosomes, including the possible existence of multiple centres of inactivation.
