Motion perception deficits in glaucomatous optic neuropathy

AbstractThe mechanisms mediating impaired motion perception in glaucoma were investigated. Direction discrimination thresholds for low (4.2 deg/sec) and high (12.5 deg/sec) velocity random-dot kinematograms were measured in controls and patients with glaucoma or ocular hypertension. Thresholds were elevated significantly in glaucoma patients and individual ocular hypertensives. Threshold elevations were not due to blur or pupil size. After compensating for motion reversals, high but not low velocity thresholds remained elevated. Only high velocity thresholds correlated with differential luminance sensitivity. A hypothesis that different mechanisms mediate glaucoma-induced deficits at high and low velocities is presented

Повторные измерения толщины слоя нервных волокон с помощью оптического когерентного томографа Stratus

PURPOSE: Assessment of optic disc damage is an essential part of the ocular examination and differential diagnosis between the patient with ocular hypertension and pre-perimetric or perimetric glaucoma. The Stratus optic coherent tomograph (Carl Zeiss Meditec, Inc, Dublin, Calif) is still one of the most used optic nerve imaging technology throughout the world. Therefore, the development of methodology that enhances the utility of optic disc measurements with the Stratus OCT remains a relevant and meaningful goal. In an attempt to determine the optimal number of repeated measurements we investigated how the average of three sets of manually repeated measurements of retina nerve firer layer (RNFL) thickness would compare with a single set. METHODS: A total of 73 individuals (136 eyes) aged 55.3±15.2 years with ocular hypertensive (OHT), pre-peri-metric glaucoma or glaucoma were included in the final analysis. When the data was evaluated using a quadrant analysis we observed that 13.6% of the patients exhibited a clinically meaningful difference of 20% or more in the serial RNFL thickness measurements. RESULTS: The difference ranged from 9.3 to 32.7 microns and in 10 of the 12 quadrants the averaged measurement exceeded the initial measurement. Most of the differences demonstrated in this study occurred in the horizontal meridian and are probably a result of instinctive saccadic eye movements. A difference in the vertical meridian (superior and/or inferior quadrants) which is the more relevant meridian for changes in glaucoma was seen in only 3 patients (4.1%). CONCLUSIONS: One reliable RNFL measurement would be sufficient in most of these cases because in 95.9% of the cases the differences observed for the vertical meridian were less than 20%. Nevertheless, it is important to recognize that there can be more variability in the horizontal meridian and that in cases with visual loss encroaching on fixation serial measurements may be useful. At any rate, as with all ancillary tests, whenever a change is detected, it is wise to repeat the test to verify the results.ЦЕЛЬ. Оценка изменений в диске зрительного нерва является важной частью офтальмологического обследования и дифференциальной диагностики у пациентов с офтальмогипертензией и ранней и развитой стадиями глаукомы. Оптический когерентный томограф Stratus (Carl Zeiss Meditec, Inc, Dublin, Calif) до сих пор является одним из самых часто используемых приборов для визуализации зрительного нерва по всему миру. Поэтому разработка методологии, оптимизирующей оценку состояния диска зрительного нерва с помощью Stratus, остается важной и актуальной задачей. В попытке определить оптимальное количество последовательных измерений, мы сравнивали результаты одиночного измерения толщины слоя нервных волокон с усредненными результатами серии из трех последовательных измерений. методы. Всего в исследовании участвовало 73 пациента (136 глаз) в возрасте 55,3±15,2 года с офтальмогипертензией или диагностированной глаукомой. При анализе полученных данных по квадрантам поля зрения у 13,6% пациентов было обнаружено клинически значимое различие ≥ 20% в толщине слоя нервных волокон. РЕЗУЛЬТАТЫ. Разница в измерениях составляла от 9,3 до 32,7 мкм, и в 10 из 12 квадрантов усредненный результат трех последовательных измерений превышал результат единичного измерения. В большинстве случав различие отмечалось в горизонтальном меридиане и, вероятно, являлось результатом естественных саккадных движений. Различие в результатах по более значимому для изменений поля зрения при глаукоме вертикальному меридиану (верхние и/или нижние квадранты) наблюдалось только у 3 (4,1%) пациентов. ЗАКЛЮЧЕНИЕ. Поскольку в 95,9% случаев разница результатов по вертикальному меридиану не превышает 20%, можно сделать вывод, что в большинстве случаев достаточно одного достоверного измерения толщины слоя нервных волокон сетчатки. Тем не менее полезно помнить о большей вариабельности результатов по горизонтальному меридиану. Например, в случае со снижением зрения, затрудняющим фиксацию взгляда, может быть полезным проведение серии из нескольких исследований подряд. В любом случае при появлении изменений в результатах этого или других вспомогательных исследований наилучшей тактикой является повторение исследования для подтверждения результатов

A physical map of Brassica oleracea shows complexity of chromosomal changes following recursive paleopolyploidizations

<p>Abstract</p> <p>Background</p> <p>Evolution of the Brassica species has been recursively affected by polyploidy events, and comparison to their relative, <it>Arabidopsis thaliana</it>, provides means to explore their genomic complexity.</p> <p>Results</p> <p>A genome-wide physical map of a rapid-cycling strain of <it>B. oleracea </it>was constructed by integrating high-information-content fingerprinting (HICF) of Bacterial Artificial Chromosome (BAC) clones with hybridization to sequence-tagged probes. Using 2907 contigs of two or more BACs, we performed several lines of comparative genomic analysis. Interspecific DNA synteny is much better preserved in euchromatin than heterochromatin, showing the qualitative difference in evolution of these respective genomic domains. About 67% of contigs can be aligned to the Arabidopsis genome, with 96.5% corresponding to euchromatic regions, and 3.5% (shown to contain repetitive sequences) to pericentromeric regions. Overgo probe hybridization data showed that contigs aligned to Arabidopsis euchromatin contain ~80% of low-copy-number genes, while genes with high copy number are much more frequently associated with pericentromeric regions. We identified 39 interchromosomal breakpoints during the diversification of <it>B. oleracea </it>and <it>Arabidopsis thaliana</it>, a relatively high level of genomic change since their divergence. Comparison of the <it>B. oleracea </it>physical map with Arabidopsis and other available eudicot genomes showed appreciable 'shadowing' produced by more ancient polyploidies, resulting in a web of relatedness among contigs which increased genomic complexity.</p> <p>Conclusions</p> <p>A high-resolution genetically-anchored physical map sheds light on Brassica genome organization and advances positional cloning of specific genes, and may help to validate genome sequence assembly and alignment to chromosomes.</p> <p>All the physical mapping data is freely shared at a WebFPC site (<url>http://lulu.pgml.uga.edu/fpc/WebAGCoL/brassica/WebFPC/</url>; Temporarily password-protected: account: pgml; password: 123qwe123.</p

Analysis of the bread wheat genome using whole-genome shotgun sequencing

Citation: Brenchley, R., Spannagl, M., Pfeifer, M., . . . & Hall, N. (2012). Analysis of the bread wheat genome using whole-genome shotgun sequencing. Nature, 491(1), 705-709. https://doi.org/10.1038/nature11650Bread wheat (Triticum aestivum) is a globally important crop, accounting for 20 per cent of the calories consumed by humans. Major efforts are underway worldwide to increase wheat production by extending genetic diversity and analysing key traits, and genomic resources can accelerate progress. But so far the very large size and polyploid complexity of the bread wheat genome have been substantial barriers to genome analysis. Here we report the sequencing of its large, 17-gigabase-pair, hexaploid genome using 454 pyrosequencing, and comparison of this with the sequences of diploid ancestral and progenitor genomes. We identified between 94,000 and 96,000 genes, and assigned two-thirds to the three component genomes (A, B and D) of hexaploid wheat. High-resolution synteny maps identified many small disruptions to conserved gene order. We show that the hexaploid genome is highly dynamic, with significant loss of gene family members on polyploidization and domestication, and an abundance of gene fragments. Several classes of genes involved in energy harvesting, metabolism and growth are among expanded gene families that could be associated with crop productivity. Our analyses, coupled with the identification of extensive genetic variation, provide a resource for accelerating gene discovery and improving this major crop