The value of twins in dental research

The document attached has been archived with permission from the Australian Dental Association. An external link to the publisher’s copy is included.Due to recent advances in molecular genetics, studies of twins will continue to provide important insights into how genetic and environmental factors contribute to variation in human physical and behavioural traits and disorders. This review emphasizes that biometrical genetic studies of twins are particularly valuable in complementing and directing molecular approaches to facilitate the detection of quantitative trait loci. It also describes several other research models involving twins, apart from the traditional comparison of similarities in monozygotic (identical) and dizygotic (nonidentical) pairs, that have the potential to provide new information in the future. Current knowledge about the genetic bases of common dental problems is summarized and future directions in dental research involving twins are outlined.GC Townsend, L Richards, T Hughes, S Pinkerton, W Schwerd

Caracterización de la ictiofauna en la Laguna del Monte, provincia de Buenos Aires

The purpose of this study was to describe as well as to characterize the fish populations living in Del Monte lagoon, which belongs to the Encadenadas del Oeste system in the province of Buenos Aires, Argentina. This research was carried out using trammel nets with meshes of six different sizes at three sampling stations during October 2003. The species captured in the area of study were firstly identified. The specific diversity of each fishing site was subsequently estimated. In addition, sex ratio, size structure, and the relative abundance both in number and weight were also determined for each species. Total capture included 647 individuals, which corresponded to the following six species: mojarra Astyanax eigenmanniorum, dientudo Oligosarcus jenynsii, pejerrey Odontesthes bonariensis, carp Cyprinus carpio, sabalito Cyphocharax voga, and catfish Rhamdia quelen. The specific diversity was very similar at the three sampling stations. The mojarra Astyanax eigenmanniorum evidenced the highest relative abundance in number, it was followed by the dientudo Oligosarcus jenynsii and the pejerrey Odontesthes bonariensis. The highest ichthyomass corresponded to the carp Cyprinus carpio. The entrance of the latter to the Del Monte lagoon was corroborated, the highest number of samples was recorded near the outlet of Guaminí and Malleo-Leufú brooks. A marked decrease in the abundance of the pejerrey Odontesthes bonariensis as well as an increase in the number of the dientudo Oligosarcus jenynsii and the mojarra Astyanax eigenmanniorum were also observed.The purpose of this study was to describe as well as to characterize the fish populations living in Del Monte lagoon, which belongs to the Encadenadas del Oeste system in the province of Buenos Aires, Argentina. This research was carried out using trammel nets with meshes of six different sizes at three sampling stations during October 2003. The species captured in the area of study were firstly identified. The specific diversity of each fishing site was subsequently estimated. In addition, sex ratio, size structure, and the relative abundance both in number and weight were also determined for each species. Total capture included 647 individuals, which corresponded to the following six species: mojarra Astyanax eigenmanniorum, dientudo Oligosarcus jenynsii, pejerrey Odontesthes bonariensis, carp Cyprinus carpio, sabalito Cyphocharax voga, and catfish Rhamdia quelen. The specific diversity was very similar at the three sampling stations. The mojarra Astyanax eigenmanniorum evidenced the highest relative abundance in number, it was followed by the dientudo Oligosarcus jenynsii and the pejerrey Odontesthes bonariensis. The highest ichthyomass corresponded to the carp Cyprinus carpio. The entrance of the latter to the Del Monte lagoon was corroborated, the highest number of samples was recorded near the outlet of Guaminí and Malleo-Leufú brooks. A marked decrease in the abundance of the pejerrey Odontesthes bonariensis as well as an increase in the number of the dientudo Oligosarcus jenynsii and the mojarra Astyanax eigenmanniorum were also observed

Caracterización de la ictiofauna en la Laguna del Monte, provincia de Buenos Aires

The purpose of this study was to describe as well as to characterize the fish populations living in Del Monte lagoon, which belongs to the Encadenadas del Oeste system in the province of Buenos Aires, Argentina. This research was carried out using trammel nets with meshes of six different sizes at three sampling stations during October 2003. The species captured in the area of study were firstly identified. The specific diversity of each fishing site was subsequently estimated. In addition, sex ratio, size structure, and the relative abundance both in number and weight were also determined for each species. Total capture included 647 individuals, which corresponded to the following six species: mojarra Astyanax eigenmanniorum, dientudo Oligosarcus jenynsii, pejerrey Odontesthes bonariensis, carp Cyprinus carpio, sabalito Cyphocharax voga, and catfish Rhamdia quelen. The specific diversity was very similar at the three sampling stations. The mojarra Astyanax eigenmanniorum evidenced the highest relative abundance in number, it was followed by the dientudo Oligosarcus jenynsii and the pejerrey Odontesthes bonariensis. The highest ichthyomass corresponded to the carp Cyprinus carpio. The entrance of the latter to the Del Monte lagoon was corroborated, the highest number of samples was recorded near the outlet of Guaminí and Malleo-Leufú brooks. A marked decrease in the abundance of the pejerrey Odontesthes bonariensis as well as an increase in the number of the dientudo Oligosarcus jenynsii and the mojarra Astyanax eigenmanniorum were also observed.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Instituto de Limnología "Dr. Raul A. Ringuelet" (ILPLA

Caracterización de la ictiofauna en la Laguna del Monte, provincia de Buenos Aires

The purpose of this study was to describe as well as to characterize the fish populations living in Del Monte lagoon, which belongs to the Encadenadas del Oeste system in the province of Buenos Aires, Argentina. This research was carried out using trammel nets with meshes of six different sizes at three sampling stations during October 2003. The species captured in the area of study were firstly identified. The specific diversity of each fishing site was subsequently estimated. In addition, sex ratio, size structure, and the relative abundance both in number and weight were also determined for each species. Total capture included 647 individuals, which corresponded to the following six species: mojarra Astyanax eigenmanniorum, dientudo Oligosarcus jenynsii, pejerrey Odontesthes bonariensis, carp Cyprinus carpio, sabalito Cyphocharax voga, and catfish Rhamdia quelen. The specific diversity was very similar at the three sampling stations. The mojarra Astyanax eigenmanniorum evidenced the highest relative abundance in number, it was followed by the dientudo Oligosarcus jenynsii and the pejerrey Odontesthes bonariensis. The highest ichthyomass corresponded to the carp Cyprinus carpio. The entrance of the latter to the Del Monte lagoon was corroborated, the highest number of samples was recorded near the outlet of Guaminí and Malleo-Leufú brooks. A marked decrease in the abundance of the pejerrey Odontesthes bonariensis as well as an increase in the number of the dientudo Oligosarcus jenynsii and the mojarra Astyanax eigenmanniorum were also observed.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Instituto de Limnología "Dr. Raul A. Ringuelet" (ILPLA

Altered expression of genes implicated in xylan biosynthesis affects penetration resistance against powdery mildew

Heteroxylan has recently been identified as an important component of papillae, which are formed during powdery mildew infection of barley leaves. Deposition of heteroxylan near the sites of attempted fungal penetration in the epidermal cell wall is believed to enhance the physical resistance to the fungal penetration peg and hence to improve pre-invasion resistance. Several glycosyltransferase (GT) families are implicated in the assembly of heteroxylan in the plant cell wall, and are likely to work together in a multi-enzyme complex. Members of key GT families reported to be involved in heteroxylan biosynthesis are up-regulated in the epidermal layer of barley leaves during powdery mildew infection. Modulation of their expression leads to altered susceptibility levels, suggesting that these genes are important for penetration resistance. The highest level of resistance was achieved when a GT43 gene was co-expressed with a GT47 candidate gene, both of which have been predicted to be involved in xylan backbone biosynthesis. Altering the expression level of several candidate heteroxylan synthesis genes can significantly alter disease susceptibility. This is predicted to occur through changes in the amount and structure of heteroxylan in barley papillae.Jamil Chowdhury, Stefanie Lück, Jeyaraman Rajaraman, Dimitar Douchkov, Neil J. Shirley, Julian G. Schwerdt, Patrick Schweizer, Geoffrey B. Fincher, Rachel A. Burton and Alan Littl

Genetic diversity and genome wide association study of β-glucan content in tetraploid wheat grains

Non-starch polysaccharides (NSPs) have many health benefits, including immunomodulatory activity, lowering serum cholesterol, a faecal bulking effect, enhanced absorption of certain minerals, prebiotic effects and the amelioration of type II diabetes. The principal components of the NSP in cereal grains are (1,3;1,4)-β-glucans and arabinoxylans. Although (1,3;1,4)-β-glucan (hereafter called β-glucan) is not the most representative component of wheat cell walls, it is one of the most important types of soluble fibre in terms of its proven beneficial effects on human health. In the present work we explored the genetic variability of β-glucan content in grains from a tetraploid wheat collection that had been genotyped with a 90k-iSelect array, and combined this data to carry out an association analysis. The β-glucan content, expressed as a percentage w/w of grain dry weight, ranged from 0.18% to 0.89% across the collection. Our analysis identified seven genomic regions associated with β-glucan, located on chromosomes 1A, 2A (two), 2B, 5B and 7A (two), confirming the quantitative nature of this trait. Analysis of marker trait associations (MTAs) in syntenic regions of several grass species revealed putative candidate genes that might influence β-glucan levels in the endosperm, possibly via their participation in carbon partitioning. These include the glycosyl hydrolases endo-β-(1,4)-glucanase (cellulase), β-amylase, (1,4)-β-xylan endohydrolase, xylanase inhibitor protein I, isoamylase and the glycosyl transferase starch synthase II

Mygalomorphae spider community of the Natural Reserve Sierra del Tigre, Tandilia, Buenos Aires, Argentina

We documented the specific richness, abundance and activity of the Mygalomorph spider community in the Natural Reserve Sierra del Tigre, Buenos Aires, Argentina. This hilly ecosystem is home for many endemic species and rich in native fauna and flora. Spider abundance was sampled monthly from May 2011 - May 2012 by hand capture and pitfall traps. The species recorded in the study area were Actinopus sp. 1 (Actinopodidae), Grammostola vachoni Schiapelli y Gerschman, 1960; Plesiopelma longisternale Schiapelli y Gerschman, 1942 and Catumiri argentinense (Mello-Leitão, 1941) (Theraphosidae). Grammostola vachoni was the dominant species in hand capture and Actinopus sp. 1 in pitfall traps. The seasonal variation, diversity, and abundance of the mygalomorph community are analyzed and discussed here. The Mygalomorphae of the Tandilia system comprises an important group of sedentary and cryptozoic spiders that seem to be dependent on habitat type and environmental factors.En el presente trabajo se analizó la riqueza específica, abundancia y actividad de la comunidad de arañas Mygalomorphae en la Reserva Natural Sierra del Tigre, Buenos Aires, Argentina. Este ecosistema serrano alberga numerosas especies endémicas y es rico en fauna y flora nativa. La abundancia de arañas se muestreó mensualmente desde mayo de 2011 a mayo de 2012, mediante recolección manual y trampas de caída. Las especies registradas en el área de estudio fueron Actinopus sp. 1 (Actinopodidae), Grammostola vachoni Schiapelli y Gerschman, 1960; Plesiopelma longisternale Schiapelli y Gerschman, 1942 y Catumiri argentinense (Mello-Leitão, 1941) (Theraphosidae). Grammostola vachoni resultó la especie dominante en la recolección manual y Actinopus sp. 1 en trampas de caída. Se discuten y analizan la variación estacional, diversidad y abundancia de la comunidad de migalomorfas. Las Mygalomorphae del sistema de Tandilia comprenden un grupo importante de arañas sedentarias y criptozoicas que parecen depender del tipo de ambiente y factores ambientales.Centro de Estudios Parasitológicos y de Vectore

Mygalomorphae spider community of the Natural Reserve Sierra del Tigre, Tandilia, Buenos Aires, Argentina

We documented the specific richness, abundance and activity of the Mygalomorph spider community in the Natural Reserve Sierra del Tigre, Buenos Aires, Argentina. This hilly ecosystem is home for many endemic species and rich in native fauna and flora. Spider abundance was sampled monthly from May 2011 - May 2012 by hand capture and pitfall traps. The species recorded in the study area were Actinopus sp. 1 (Actinopodidae), Grammostola vachoni Schiapelli y Gerschman, 1960; Plesiopelma longisternale Schiapelli y Gerschman, 1942 and Catumiri argentinense (Mello-Leitão, 1941) (Theraphosidae). Grammostola vachoni was the dominant species in hand capture and Actinopus sp. 1 in pitfall traps. The seasonal variation, diversity, and abundance of the mygalomorph community are analyzed and discussed here. The Mygalomorphae of the Tandilia system comprises an important group of sedentary and cryptozoic spiders that seem to be dependent on habitat type and environmental factors.En el presente trabajo se analizó la riqueza específica, abundancia y actividad de la comunidad de arañas Mygalomorphae en la Reserva Natural Sierra del Tigre, Buenos Aires, Argentina. Este ecosistema serrano alberga numerosas especies endémicas y es rico en fauna y flora nativa. La abundancia de arañas se muestreó mensualmente desde mayo de 2011 a mayo de 2012, mediante recolección manual y trampas de caída. Las especies registradas en el área de estudio fueron Actinopus sp. 1 (Actinopodidae), Grammostola vachoni Schiapelli y Gerschman, 1960; Plesiopelma longisternale Schiapelli y Gerschman, 1942 y Catumiri argentinense (Mello-Leitão, 1941) (Theraphosidae). Grammostola vachoni resultó la especie dominante en la recolección manual y Actinopus sp. 1 en trampas de caída. Se discuten y analizan la variación estacional, diversidad y abundancia de la comunidad de migalomorfas. Las Mygalomorphae del sistema de Tandilia comprenden un grupo importante de arañas sedentarias y criptozoicas que parecen depender del tipo de ambiente y factores ambientales.Centro de Estudios Parasitológicos y de Vectore

How to survey displaced workers in Switzerland ? Sources of bias and ways around them

Studying career outcomes after job loss is challenging because individually displaced worker form a self-selected group. Indeed, the same factors causing the workers to lose their jobs, such as lack of motivation, may also reduce their re-employment prospects. Using data from plant closures where all workers were displaced irrespective of their individual characteristics offers a way around this selection bias. There is no systematic data collection on workers displaced by plant closure in Switzerland. Accordingly, we conducted our own survey on 1200 manufacturing workers who had lost their job 2 years earlier. The analysis of observational data gives rise to a set of methodological challenges, in particular nonresponse bias. Our survey addressed this issue by mixing data collection modes and repeating contact attempts. In addition, we combined the survey data with data from the public unemployment register to examine the extent of nonresponse bias. Our analysis suggests that some of our adjustments helped to reduce bias. Repeated contact attempts increased the response rate, but did not reduce nonresponse bias. In contrast, using telephone interviews in addition to paper questionnaires helped to substantially improve the participation of typically underrepresented subgroups. However, the survey respondents still differ from nonrespondents in terms of age, education and occupation. Interestingly, these differences have no significant impact on the substantial conclusion about displaced workers' re-employment prospects

Genetics and physiology of cell wall polysaccharides in the model C(4) grass, Setaria viridis spp

Published: 2 October 2015BACKGROUND: Setaria viridis has emerged as a model species for the larger C4 grasses. Here the cellulose synthase (CesA) superfamily has been defined, with an emphasis on the amounts and distribution of (1,3;1,4)-β-glucan, a cell wall polysaccharide that is characteristic of the grasses and is of considerable value for human health. METHODS: Orthologous relationship of the CesA and Poales-specific cellulose synthase-like (Csl) genes among Setaria italica (Si), Sorghum bicolor (Sb), Oryza sativa (Os), Brachypodium distachyon (Bradi) and Hordeum vulgare (Hv) were compared using bioinformatics analysis. Transcription profiling of Csl gene families, which are involved in (1,3;1,4)-β-glucan synthesis, was performed using real-time quantitative PCR (Q-PCR). The amount of (1,3;1,4)-β-glucan was measured using a modified Megazyme assay. The fine structures of the (1,3;1,4)-β-glucan, as denoted by the ratio of cellotriosyl to cellotetraosyl residues (DP3:DP4 ratio) was assessed by chromatography (HPLC and HPAEC-PAD). The distribution and deposition of the MLG was examined using the specific antibody BG-1 and captured using fluorescence and transmission electron microscopy (TEM). RESULTS: The cellulose synthase gene superfamily contains 13 CesA and 35 Csl genes in Setaria. Transcript profiling of CslF, CslH and CslJ gene families across a vegetative tissue series indicated that SvCslF6 transcripts were the most abundant relative to all other Csl transcripts. The amounts of (1,3;1,4)-β-glucan in Setaria vegetative tissues ranged from 0.2% to 2.9% w/w with much smaller amounts in developing grain (0.003% to 0.013% w/w). In general, the amount of (1,3;1,4)-β-glucan was greater in younger than in older tissues. The DP3:DP4 ratios varied between tissue types and across developmental stages, and ranged from 2.4 to 3.0:1. The DP3:DP4 ratios in developing grain ranged from 2.5 to 2.8:1. Micrographs revealing the distribution of (1,3;1,4)-β-glucan in walls of different cell types and the data were consistent with the quantitative (1,3;1,4)-β-glucan assays. CONCLUSION: The characteristics of the cellulose synthase gene superfamily and the accumulation and distribution of (1,3;1,4)-β-glucans in Setaria are similar to those in other C4 grasses, including sorghum. This suggests that Setaria is a suitable model plant for cell wall polysaccharide biology in C4 grasses.Riksfardini A. Ermawar, Helen M. Collins, Caitlin S. Byrt, Marilyn Henderson, Lisa A. O'Donovan, Neil J. Shirley, Julian G. Schwerdt, Jelle Lahnstein, Geoffrey B. Fincher and Rachel A. Burto