Orientador: Elaine Sbroggio de Oliveira Rodini / Banca: Adriana Camargo Ferrasi / Banca: Tânia Yoshico Kamiya / Resumo: Introdução: A infertilidade é definida como a incapacidade de um casal obter uma gravidez ou parto de um bebê vivo. Ela não é exclusiva da mulher, mas sim do casal, e os fatores mais comuns associados são de origem genética, como alterações dos cromossomos, incluindo também causas hormonais, anatômicas, infecciosas, imunológicas, entre outras. A definição dos tipos de alterações cromossômicas presentes em um casal com dificuldades reprodutivas é de fundamental importância para sua vida reprodutiva. Objetivo: Verificar a importância das diferentes alterações cromossômicas na etiologia da infertilidade e discutir a indicação do cariótipo nos casos de dificuldades reprodutivas. Metodologia: Estudo retrospectivo de dados de 832 indivíduos, atendidos na Faculdade de Ciências/ UNESP, Bauru, no período de Janeiro de 2005 a Dezembro de 2012, referentes a estudos cromossômicos (cariótipo de sangue periférico e abortos espontâneos) e anamnese. Resultados: Dos 832 casos, 431 foram avaliados através dos cariótipos de sangue periférico e 514 através de seus cariótipos de abortos espontâneos; 113 foram avaliados tanto pelos cariótipos de sangue como pelos cariótipos de seus abortos. A frequência das alterações cromossômicas em sangue periférico foi de 5,6%, e de 32,5 % em abortos espontâneos. Não houve correlação estatística entre ocorrência das alterações cromossômicas, sexo, idade e número de abortos. Conclusões: Na população estudada observou-se que as alterações cromossômicas são importantes na etiologia da infertilidade. As alterações cromossômicas numéricas nos abortos são as mais frequentes; contudo, sua ocorrência pode ser maior devido a possível superestimação dos cariótipos normais pela contaminação de material materno. Para prevenção de malformações congênitas, ambos os membros do casal relacionados a problemas reprodutivos devem realizar o estudo cromossômico / Abstract: Introduction: Infertility is defined as the inability of a couple of getting pregnant or give birth to a live baby. It is not only related to women, but also to the couple, and the most common factors associated are genetic, such as chromosome abnormalities as well as hormonal, anatomical, infectious and immunological causes, among others. The definition of the types of chromosomal abnormalities present in a couple with reproductive difficulties is of fundamental importance to their reproductive life. Objective: To assess the importance of different chromosomal abnormalities in the etiology of infertility and discuss the indication of the karyotype in cases of reproductive difficulties. Methodology: Karyotypes of peripheral blood and miscarriages (Chromosomal studies) and anamnesis of 832 individuals attended at the Faculdade de Ciências/ UNESP, Bauru, from January 2005 to December 2012 were assessed retrospectively. Results: Of the 832 cases, 431 were evaluated by peripheral blood karyotypes and 514 through their karyotypes of miscarriages; 113 were evaluated both by karyotypes of both blood and abortions. The frequency of chromosomal abnormalities in peripheral blood was 5.6%, and 32.5% in spontaneous abortions. There was no statistical correlation between occurrence of chromosomal abnormalities, sex, age and number of abortions. Conclusions: Chromosomal abnormalities are important in the etiology of infertility within the population studied. The numerical chromosomal abnormalities in abortions were the most common; however, its occurrence may be higher due to possible overestimation of normal karyotypes by contamination of maternal material. Aiming the prevention of congenital malformations, both couple members presenting reproductive problems should perform a chromosome study / Mestre

Kwok, Tsz Piu. / Thesis M.Phil. Chinese University of Hong Kong 2015. / Includes bibliographical references (leaves 109-120). / Abstracts also in Chinese. / Title from PDF title page (viewed on 04, January, 2017).

Orientador: Danilo Moretti-Ferreira / Coorientador: Dennis Drayna / Banca: Ana Maria Schiefer / Banca: Maria Isabel de Souza Aranha Melaragno / Banca: Robson Francisco Carvalho / Banca: Ester Silveira Ramos / Resumo: A gagueira é uma doença comum que afeta a fluência da fala, caracterizada por repetições ou prolongamentos frequentes de sons, sílaba, palavras, ou por hesitações, ou interrupções no fluxo normal da fala. Trata-se de uma doença que tipicamente surge na infância em crianças com idade entre dois e quatro anos, com taxa de incidência estimada em torno de 5% da população. No entanto devido à elevada taxa de recuperação espontânea, estima-se uma prevalência de 1% na população em geral. Apesar do envolvimento de fatores ambientais, o fator genético é determinante para o desenvolvimento da doença. Algumas evidências que sustentam essa relação são: agregação familial, estudos com gêmeos e envolvendo adoções e, relações de consanguinidade em famílias com diversos afetados. Entretanto, trata-se de uma doença complexa na qual a identificação exata do tipo de herança é difícil de ser determinada uma vez que não seguem as leis de Mendel. Este estudo teve como principal finalidade realizar análises de ligação em 43 famílias brasileiras do Estado de São Paulo, não relacionadas, portadoras de gagueira desenvolvimental persistente a fim de identificar regiões cromossômicas com possíveis genes candidatos; Para as análises de ligação, inicialmente foi realizada a genotipagem de todas as famílias através de chips específicos para essa finalidade contendo 6056 marcadores SNP. Posteriormente, para o refinamento do mapa de ligação foram utilizados marcadores microssatélites polimórficos marcados com fluoróforos e analisados em sequenciador automático capilar. Para as estimativas das frequências alélicas destes marcadores na população brasileira foram utilizados amostras do grupo controle, não relacionadas, previamente selecionadas. Apenas duas famílias (BRPD_47 e BRPD_50) sob o padrão de herança dominante... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Stuttering is a common disease that affects the fluency of speech, and is characterized by frequent repetitions or prolongations of sounds, syllables, or words, or by interruptions in the normal flow of speech. The disorder typically begins in children aged two to four years, and has an estimated incidence rate of around 5% of the population. Due to the high rate of spontaneous recovery, the estimated prevalence of the disorder is 1% in the general population. Despite the involvement of environmental factors, genetic factors have been shown to be critical to the development of the disease. Evidence supporting genetic factors include twin studies, adoption studies, family clusters of stuttering, and consanguineous relations in families with many cases of the disorder. However stuttering is a complex disorder in which the identification of the exact type of inheritance is difficult to determine because it does not follow Mendelian laws. The main goal of this study was to perform a genome-wide linkage analysis in 43 unrelated families from the Brazilian state of São Paulo, which had multiple cases of persistent developmental stuttering, in an effort to identify chromosomal regions containing possible causal genes, Linkage analysis was initially performed by genotyping of all families with chip-based methods that assayed 6056 sNP markers. Subsequent refinement of linkage locations used polymorphic microsatellite markers analyzed by capillary electrophoresis unsing an automated DNA sequencer. Unrelated normal Brazilian samples were used as a control group to estimate the allele frequencies of these markers in this population. Two families (BRPD_47 and BRPD_50) showed significant evidence for linkage in the region of chromosome 10q21 under a dominant inheritance model. Combining these two families produced... (Complete abstract click electronic access below) / Doutor

Chromosome alignment is highly conserved in all eukaryotic cell divisions. Microtubule (MT) -based forces generated by the mitotic spindle are integral for proper chromosome alignment and equal chromosome segregation. The kinetochore is a multi-subunit protein complex that assembles on centromeric regions of chromosomes. Kinetochores tether chromosomes to MTs (K fibers) that emanate from opposite poles, in a process called biorientation. This linkage translates K fiber dynamics into chromosome movements during alignment and segregation. Stable, high-affinity kinetochore attachments promote spindle assembly checkpoint (SAC) silencing, which is active when unattached kinetochores are present. During chromosome alignment, 1) K fiber plus-end dynamics decrease, confining chromosome movements near the spindle equator, and 2) electrostatic interactions between kinetochore proteins and MTs increase. Chromosome segregation occurs as soon as all chromosomes are stably attached to microtubules and the SAC has been silenced. SAC silencing and chromosome alignment are temporally coordinated during normal divisions, implying that the mechanisms regulating K fiber dynamics and kinetochore affinity must be linked. Interestingly, HeLa cells depleted of a kinesin-8 motor Kif18A, known for its role in promoting chromosome alignment, display a SAC-dependent mitotic delay due to kinetochore-MT attachment defects. This is puzzling, as Kif18A's function in chromosome alignment is to suppress MT growth by stably associating with MT plus-ends. Whether Kif18A is required for attachment in all cells and how it promotes kinetochore microtubule linkages are not understood. The work presented in this dissertation supports a model in which Kif18A functions as a molecular link that coordinates chromosome alignment and anaphase onset. We find that Kif18A is required to stabilize kinetochore-MT attachments during mammalian germline development, as germline precursor cells in Kif18A mutant mice are unable to divide during embryogenesis due to an active SAC. However, while all cell types require functional Kif18A for chromosome alignment, mouse primary somatic cells can still divide with normal timing. This finding indicates a cell-type specific dependence on Kif18A for stabilizing kinetochore-MT attachments, and provides evidence that this function might be separate from Kif18A's known role in chromosome alignment. Consistent with this idea, we find that an evolutionarily conserved binding motif for protein phosphatase 1 (PP1) is required for Kif18A's novel role in regulating kinetochore microtubule attachments. Kif18A-PP1 interaction is required for Kif18A-mediated dephosphorylation of the kinetochore protein Hec1, which enhances attachment. However, Kif18A's interaction with PP1 is dispensable for chromosome alignment. Thus, point mutations that disrupt PP1 binding separate Kif18A's role in stabilizing kinetochore attachments from its function in promoting chromosome alignment. Additionally, through structure function studies of the motor domain, we identified a long surface loop (Loop2) that is required for Kif18A's unique MT plus-end binding activity, which is essential for its function in confining chromosome movements. Taken together, we find that Kif18A is molecularly tuned to provide temporal control of chromosome alignment and anaphase entry.

Chromosome evaluations were made on leukocyte blood samples from 169 phenotypically normal nulliparous Holstein heifers. These were from three different reproduction groups collected in sets of threes from 10 different herds in the western United States. Group 1, the control group, consisted of heifers diagnosed pregnant after one or two breedings; Group 2 consisted of heifers diagnosed pregnant after three or four breedings; and Group 3 consisted of heifers diagnosed open after four or more breedings. Metaphase chromosome spreads used in these analyses were obtained through 72-hour leukocyte cultures from heparinized whole blood. Processed cells were dropped onto a slide, air-dried, and stained with Giemsa. Chromosomes were then counted and X chromosomes were identified. A total of 1, 597 cells was evaluated, with 1,439 cells having counts of 60 chromosomes each. Thirty cells had less than 58 chromosomes, 31 cells had 58 chromosomes, 75 cells had 59 chromosomes, 14 cells had 61 chromosomes, and 8 cells had more than 61 chromosomes (9 .98% were different than 60). All counts of other than 60 chromosomes were isolated cases and were not identified as abnormalities. Only two cells from two separate heifers contained what may have been sex chromosome abnormalities. No persistent chromosomal defects were observed among the 169 heifers.

Paget's disease of the bone is a skeletal disorder of unknown cause. This disease is characterised by excessive and abnormal bone remodelling brought about by increased bone resorption followed by disorganised bone formation. Increased bone turnover results in a disorganised mosaic of woven and lamellar bone at affected skeletal sites. This produces bone that is expanded in size, less compact, more vascular, and more susceptible to deformity or fracture than normal bone. Symptoms of Paget's disease may include bone pain, bone deformity, excessive warmth over bone from hypervascularity, secondary arthritis, and a variety of neurologic complications caused in most instances by compression of the neural tissues adjacent to pagetic bone. Genetic factors play a role in the pathogenesis of Paget's disease but the molecular basis remains largely unknown. The identification of the molecular basis of Paget's disease is fundamental for an understanding of the cause of the disease, for identifying subjects at risk at a preclinical stage, and for the development of more effective preventive and therapeutic strategies for the management of the condition. With this in mind, the aim of this project is to identify genetic loci, in a large pedigree, that may harbour genes responsible for Paget's disease of bone. A large Australian family with evidence of Paget's disease was recruited for these studies (Chapter 3). This pedigree has characterised over 250 individuals, with 49 informative individuals affected with Paget's disease of bone, 31 of whom are available for genotypic analysis. The pattern of disease in these individuals is polystotic, with sites of involvement including the spine, pelvis, skull and femur. Although the affected individuals have a severe early-onset form of the disease, the clinical features of the pedigree suggest that the affected family members have Paget's disease and not familial expansile osteolysis (a disease with some similarities to Paget's disease), as our patients have extensive skull and axial skeletal involvement. The disease is inherited as an autosomal dominant trait in the pedigree with high penetrance by the sixth decade. Due to the large size of this family and multiple affected members, this pedigree is a unique resource for the detection of the susceptibility gene in Paget's disease. The first susceptibility loci for Paget's disease of bone have been mapped by other investigators to chromosome 6p21 (PDB1) and 18q21.1-q22 (PDB2) in different pedigrees. Linkage analysis of the Australian pedigree in these studies was performed with markers at PDB1: these data showed significant exclusion of linkage, with LOD scores < - 2 in this region (Chapter 4). Linkage analysis of microsatellite markers from the PDB2 region excluded linkage with this region also, with a 30 cM exclusion region (LOD score < -2.0) centred on D18S42 (Chapter 4). This locus on chromosome 18q21.1-q22 contains a serine protease (serpin) cluster with similarities to chromosome 6p21. Linkage analysis of this region also failed to provide evidence of linkage to this locus (Chapter 4). These data are consistent with genetic heterogeneity of Paget's disease of bone. A gene essential for osteoclast formation encoding receptor activator of nuclear factor-kB (RANK), TNFRSF11A, has been previously mapped to the PDB2 region. Mutations in the TNFRSF11A gene have been identified segregating in pedigrees with Familial Expansile Osteolysis and early onset familial Paget's disease, however, linkage studies and mutation screening have excluded the involvement of RANK in the majority of Paget's disease patients. For the Australian pedigree, mutation screening at the TNFRSF11A locus revealed no mutations segregating with affected individuals with Paget's disease (Chapter 4). Based on these findings, our hypothesis is that a novel susceptibility gene relevant to the pathogenesis of Paget's disease of bone lies elsewhere in the genome in the affected members of this pedigree; this gene should be identifiable using a microsatellite genome-wide scan followed by positional cloning. A genome-wide scan of the Australian pedigree was carried out, followed by fine mapping and multipoint analysis in regions of interest (Chapter 5). The peak 2-point LOD scores from the genome-wide scan were LOD = 2.75 at D7S507 and LOD = 1.76 at D18S70. Two additional regions were also considered for fine mapping: chromosome 19p11-q13.1 with a LOD of 1.58 and chromosome 5q35-qter with a LOD of 1.57. Multipoint and haplotype analysis of markers flanking D7S507 did not support linkage to this region (Chapter 5). Similarly, fine mapping of chromosome 19p11-q13.1 failed to support linkage to this region (Chapter 5). Linkage analysis with additional markers in the region on chromosome 5q35-qter revealed a peak multipoint LOD score of 6.77 (Chapter 5). A distinct haplotype was shown to segregate with all members of the family, except the offspring of III-5 and III-6. Haplotype analysis of markers flanking D18S70 demonstrated a haplotype segregating with Paget's disease in a large sub-pedigree (descendants of III-3 and III-4) (Chapter 5). This sub-pedigree had a significantly lower age at diagnosis than the rest of the pedigree (51.2 + 8.5 vs. 64.2 + 9.7 years, p = 0.0012). Linkage analysis of this sub-pedigree demonstrated a peak two-point LOD score of 4.23 at marker D18S1390 (q = 0.00), and a peak multipoint LOD score of 4.71, at marker D18S70. An implication of these data is that 18q23 harbours a novel modifier gene for reducing the age of onset of Paget's disease of bone. A number of candidate Paget's genes have previously been identified on chromosome 18q23, including the nuclear factor of activated T cells (NFATc1), membrane-associated guanylated kinase (MAGUK) and a zinc finger protein. Candidate gene sequencing of these genes in these studies has failed to identify mutations segregating with affected family members in the sub-pedigree linked to chromosome 18q23 (Chapter 6). More recently, a mutation in the gene encoding the ubiquitin-binding protein sequestosome 1 (SQSTM/p62) has been shown to segregate with affected members of Paget's disease families of French-Canadian origin. In this study, a single base pair deletion (1215delC) was identified as segregating with the majority of affected members in the pedigree (Chapter 6). This deletion introduces a stop codon at amino acid position 392 which potentially results in early termination of the protein and loss of the ubiquitin binding domain. The three affected members of the family that do not share the affected haplotype do not carry a mutation in the coding region of SQSTM/p62. Screening of affected members from 10 further Paget's disease families identified the previously reported P392L mutation in 2 (20%) families. No SQSTM1/p62 coding mutations have been found in the remaining 8 families or in 113 aged matched controls. In conclusion, this project has identified genetic loci and mutations that segregate with individuals affected with Paget's disease. Further investigation of the functional significance of the genetic changes at these loci is expected to lead to a better understanding of the molecular basis of this disease.

Genomic imprinting is responsible for monoallelic gene expression that depends on the sex of the parent from which the alleles (one active, one silent) were inherited. X-chromosome inactivation is also a form of monoallelic gene expression. One of the two X chromosomes is transcriptionally silenced in the somatic cells of females, effectively equalising gene dosage with males who have only one X chromosome that is not complemented by a gene poor Y chromosome. X chromosome inactivation is random in eutherian mammals, but imprinted in marsupials, and in the extraembryonic membranes of some placentals. Imprinting and X inactivation have been studied in great detail in placental mammals (particularly humans and mice), and appear to occur also in marsupial mammals. However, both phenomena appear to have evolved specifically in mammals, since there is no evidence of imprinting or X inactivation in non-mammalian vertebrates, which do not show parent of origin effects and possess different sex chromosomes and dosage compensation mechanisms to mammals.¶ In order to understand how imprinting and X inactivation evolved, I have focused on the mammals most distantly related to human and mouse. I compared the sequence, location and expression of genes from major imprinted domains, and genes that regulate genomic imprinting and X-chromosome inactivation in the three extant mammalian groups and other vertebrates. Specifically, I studied the evolution of an autosomal region that is imprinted in humans and mouse, the evolution of the X-linked region thought to control X inactivation, and the evolution of the genes thought to establish and control differential expression of various imprinted loci. This thesis is presented as a collection of research papers that examines each of these topics, and a review and discussion that synthesizes my findings.¶ The first paper reports a study of the imprinted locus responsible for the human Prader-Willi and Angelman syndromes (PWS and AS). A search for kangaroo and platypus orthologues of PWS-AS genes identified only the putative AS gene UBE3A, and showed it was in a completely different genomic context to that of humans and mice. The only PWS gene found in marsupials (SNRPN) was located in tandem with its ancient paralogue SNRPB, on a different chromosome to UBE3A. Monotremes apparently have no orthologue of SNRPN. The several intronless genes of the PWS-AS domain also have no orthologues in marsupials or monotremes or non-mammal vertebrates, but all have close paralogues scattered about the genome from which they evidently retrotransposed. UBE3A in marsupials and monotremes, and SNRPN in marsupials were found to be expressed from both alleles, so are not imprinted. Thus, the PWA-AS imprinted domain was assembled from many non-imprinted components relatively recently, demonstrating that the evolution of imprinting has been an ongoing process during mammalian radiation.¶ In the second paper, I examine the evolution of the X-inactivation centre, the key regulatory region responsible for X-chromosome inactivation in humans and mice, which is imprinted in mouse extraembryonic membranes. By sequencing and aligning flanking regions across the three mammal groups and non-mammal vertebrates, I discovered that the region homologous to the X-inactivation centre, though intact in birds and frogs, was disrupted independently in marsupial and monotreme mammals. I showed that the key regulatory RNA of this locus (X-inactive specific transcript or XIST) is absent, explaining why a decade-long search for marsupial XIST was unsuccessful. Thus, XIST is eutherian-specific and is therefore not a basic requirement for X-chromosome inactivation in all mammals.¶ The broader significance of the findings reported in these two papers is explored with respect to other current work regarding the evolution and construction of imprinted loci in mammals in the form of a review. This comparison enabled me to conclude that like the PWS-AS domain and the X-inactivation centre, many domains show unexpected construction from disparate genomic elements that correlate with their acquisition of imprinting.¶ The fourth and last paper examines the evolution of CCCTC-binding Factor (CTCF) and its parologue Brother Of Regulator of Imprinted Sites (BORIS) which contribute to the establishment and interpretation of genomic imprinting at the Insulin-Like Growth Factor 2/H19 locus. In this paper I show that the duplication of CTCF giving rise to BORIS occurred much earlier than previously recognised, and demonstrate that a major change in BORIS expression (restriction to the germline) occurred in concert with the evolution of genomic imprinting. The papers that form the bulk of this thesis show that the evolution of epigenetic traits such as genomic imprinting and X-chromosome inactivation is labile and has apparently responded rapidly to different selective pressures during the independent evolution of the three mammal groups. I have introduced these papers, and discussed them generally in terms of current theories of how and why these forms of monoallelic expression have evolved in mammals.

Frequency-dependent selection has long been a popular heuristic explanation for the maintenance of genetic diversity in natural populations. Indeed, a large body of theoretical and empirical work has already gone into elucidating the causes and consequences of frequency-dependent selection. Most theoretical work, to date, has focused either on the diallelic case, or dealt with only very specific forms of frequency-dependence. A general model of the maintenance of multiallelic genetic diversity has been lacking. Here we extend a flexible general model of frequency-dependent selection, the pairwise interaction model, to the case of multiple alleles. First, we investigate the potential for genetic variation under the pairwise interaction model using a parameter-space approach. This approach involves taking a large random sample of all possible fitness sets and initial allele-frequency vectors of the model, iterating each to equilibrium from each set of random initial conditions, and measuring how often variation is maintained, and by which parameter combinations. We find that frequency- dependent selection maintains full polymorphism more often than classic constant-selection models and produces more skewed equilibrium allele frequencies. Fitness sets with some degree of rare advantage maintained full polymorphism most often, but a variety of non-obvious fitness patterns were also found to have positive potential for polymorphism. Second, we further investigate some unusual dynamics uncovered by the parameter-space approach above. Long-period allele-frequency cycles and a small number of aperiodic trajectories were detected. We measured the number, length and domains of attraction of the various attractors produced by the model. The genetic cycles produced by the model did not have periods short enough to be observable on an ecological time scale. In a real world system, allele-frequency cycling is likely to be indistinguishable from stable equilibrium when observed over short time scales. Third, we use a construction approach to model frequency-dependent selection with mutation under the pairwise interaction model. This approach involves the construction of an allelic polymorphism by bombarding an initial monomorphism with mutant alleles over many generations. We find that frequency-dependent selection is able to generate large numbers of alleles at a single locus. The construction process generates a wide range of allele- frequency distributions and genotypic fitness relationships. We find that constructed polymorphisms remain permanently invasible to new mutants. Analysis of constructed fitness sets may even reveal a signature of positive frequency dependence. Finally, we examine the numbers and distributions of fitnesses and alleles produced by construction under the pairwise interaction model with mutation from existing alleles, using several different methods of generating mutant fitnesses. We find that, relative to more general construction models, generating mutants from existing alleles lowers the average number of alleles maintained by frequency-dependent selection. Nevertheless, while the overall numbers of alleles are lower, the polymorphisms produced are more stable, with more natural allele-frequency distributions. Overall, frequency-dependent selection remains a powerful mechanism for the maintenance of genetic variation, although it does not always work in intuitively obvious ways.

Under terminal water deficit, the impact of stem carbohydrate remobilization has greater significance because post-anthesis assimilation is limited, and grain growth depends on translocation of carbohydrate reserves. The working hypothesis of this thesis is that increases in stem carbohydrates facilitate tolerance to terminal drought in wheat. The goals of this thesis are to examine this hypothesis using physiological and genetic tools; identify genes that are related to QTL for stem carbohydrate; work with wheat and barley breeders to integrate findings into the breeding program of the Department of Agricultural and Food Western Australia. The physiological data of three drought experiments (two years in a glasshouse and one year in the field) suggested the maximum level of stem water soluble carbohydrate (WSC) is not consistently related to grain weight, especially, under water deficit. The patterns of WSC accumulation after anthesis differed depending on variety and suggested that WSC degradation and translocation have different genetic determinants. Most of the carbohydrates in stem WSC in wheat are fructans. Because 1-FEH gene was an important gene in fructan degradation, the three copies of this gene (1-FEH w1, 1-FEH w2 and 1-FEH w3) were isolated from the respective genomes of bread wheat. In addition, the genes were mapped to chromosome locations and coincided with QTL for grain weight. The results of gene expression studies show that 1-FEH w3 had significantly higher levels in the stem and sheath which negatively corresponded to the level of stem WSC in two wheat varieties in both water-deficit and well-watered treatments. Strikingly, the 1-FEH w3 appeared to be activated by water deficit in Westonia but not in Kauz. The results suggest that stem WSC level is not, on its own, a reliable criterion to identify potential grain yield in wheat exposed to water deficit during grain filling. The expression of 1-FEH w3 may provide a better indicator when linked to instantaneous water use efficiency, osmotic potential and green leaf retention, and this requires validation in field grown plants. In view of the location of the contribution to grain filling of stem WSC, this is a potential candidate gene contributing to grain filling. The numerous differences of intron sequences of 1-FEH genes would provide more opportunities to find markers associated with the QTL. A new FEH gene was partially isolated from Chinese Spring and the sequence was closely related to 1-FEH genes. This gene, FEH w4, was mapped to 6AS using Chinese Spring deletion bin lines. The polymorphism of this gene was found between different bread varieties using PCRs and RFLPs, and this allowed the gene to be mapped to two populations of Hanxuan 10 × Lumai 14 and Cranbrook × Halberd. In the population of Hanxuan 10 × Lumai 14, it was close to SSR marker xgwm334 and wmc297 where the QTL of thousand grain weight and grain filling efficiency were located. This result indicated this gene might be another possible candidate gene for grain weight and grain filling in wheat.

"July, 2003" / "Amendments of the thesis" and "abbreviations (additional)" inside back cover. / Includes bibliographical references (leaves 195-231) / x, 231, [20] leaves : ill., plates ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Paediatrics, 2003