The Spliceosomal Protein Prp8 Stabilizes A Compact Conformation Of The U2-U6 Complex

The spliceosome is a large, RNA-protein complex that catalyzes pre-mRNA splicing during mRNA maturation. The RNA components (small nuclear RNA; snRNAs) of the spliceosome have been well studied and are believed to be involved in the splicing catalysis. Although proteins are essential for splicing, they may not be directly involved in catalysis. Among hundreds of proteins, Prp8 is the only protein that interacts with all of the catalytically important snRNAs. Therefore, it is hypothesized that Prp8 may catalyze splicing either by directly participating in catalysis or by stabilizing the conformation of the catalytically active spliceosome. In order to test whether or not Prp8 stabilizes the active-site conformation, we carried out single-molecule fluorescence resonance energy transfer (smFRET) experiments with catalytically important snRNAs U2 and U6 and Prp8. We observed that in the presence of Prp8, the population of the high FRET conformation of U2-U6 that is thought to be the active conformation increased indicating that one of the functions of Prp8 would be to stabilize the active site conformation of the spliceosome

Physical Properties Of Faint Meteors Through High-Resolution Observations

Small, faint meteors (with masses between 10-7 and 10-4 kg) were once part of an asteroid or comet, and collide with Earth\u27s atmosphere daily. Studying meteors is an effective way to survey the physical properties of their parent bodies. Meteor light curves and orbital information is easily obtained from wide-field observations, from which meteoroid structure can be inferred through meteoroid ablation modelling. A high-resolution narrow-field camera can provide much more detail about the poorly understood ablation processes and physical properties of the meteoroid. The goal of this thesis is to better understand the physical properties of meteors using high-resolution optical observations. In the first part of this work, wide-field and narrow-field optical observations of faint meteors were combined to determine what relationships, if any, exist between meteor light curve shapes, orbits, and fragmentation behaviour. Most meteors were found to have symmetric light curves, show fragmentation in the form of a long trail, and come from cometary bodies. More than 90% of meteors observed with the high-resolution camera system showed some form of fragmentation. Unexpectedly, the dynamically asteroidal meteoroids fragmented as often as the dynamically cometary meteoroids, suggestive of dynamical mixing or contamination. In the second part of this work, the luminous efficiency (the fraction of kinetic energy used for visible light production) of meteors was investigated. It is crucial for determining meteoroid mass, and past results vary by up to two orders of magnitude. An attempt at determining luminous efficiency through the classical ablation equations was made, and verified on simulated meteor data, while quantifying the uncertainty in the method. This was then applied to fifteen real meteor events, observed with the Canadian Automated Meteor Observatory. This is the first study which compares photometric and dynamic meteoroid masses to determine luminous efficiency, with modern high-resolution observations. Twelve of the meteors had luminous efficiency values less than 1% (agreeing with the lower end results of past studies), and there was no obvious trend with speed. A weak negative trend was observed with meteoroid mass, implying that smaller meteoroids radiate more efficiently

Image Processing Techniques for Detecting Chromosome Abnormalities

With the increasing use of Fluorescence In Situ Hybridization (FISH) probes as markers for certain genetic sequences, the requirement of a proper image processing framework is becoming a necessity to accurately detect these probe signal locations in relation to the centerline of the chromosome. Automated detection and length measurements based on the centerline relative to the centromere and the telomere coordinates would highly assist in clinical diagnosis of genetic disorders and thus improve its efficiency significantly. Although many image processing techniques have been developed for chromosomal analysis such as ’’karyotype analysis” to assist in laboratory diagnosis, they fail to provide reliable results in segmenting and extracting the centerline of chromosomes due to the high variability in shape of chromosomes on microscope slides. In this thesis we propose a hybrid algorithm that utilizes Gradient Vector Flow active contours, Discrete Curve Evolution based skeleton pruning and morphological thinning to provide a robust and accurate centerline of the chromosome, which is then used for the measurement of the FISH probe signals. Then this centerline information is used to detect the centromere location of the chromosome and the probe signal location distances were measured with respective to these landmarks. The ability to accurately detect FISH probe locations with respective to its centerline and other landmarks can provide the cytogeneticists with detailed information that could lead to a faster diagnosis

Human Metaphase Chromosome Analysis using Image Processing

Development of an effective human metaphase chromosome analysis algorithm can optimize expert time usage by increasing the efficiency of many clinical diagnosis processes. Although many methods exist in the literature, they are only applicable for limited morphological variations and are specific to the staining method used during cell preparation. They are also highly influenced by irregular chromosome boundaries as well as the presence of artifacts such as premature sister chromatid separation. Therefore an algorithm is proposed in this research which can operate with any morphological variation of the chromosome across images from multiple staining methods. The proposed algorithm is capable of calculating the segmentation outline, the centerline (which gives the chromosome length), partitioning of the telomere regions and the centromere location of a given chromosome. The algorithm also detects and corrects for the sister chromatid separation artifact in metaphase cell images. A metric termed the Candidate Based Centromere Confidence (CBCC) is proposed to accompany each centromere detection result of the proposed method, giving an indication of the confidence the algorithm has on a given localization. The proposed method was first tested for the ability of calculating an accurate width profile against a centerline based method [1] using 226 chromosomes. A statistical analysis of the centromere detection error values proved that the proposed method can accurately locate centromere locations with statistical significance. Furthermore, the proposed method performed more consistently across different staining methods in comparison to the centerline based approach. When tested with a larger data set of 1400 chromosomes collected from a set of DAPI (4\u27,6-diamidino-2-phenylindole) and Giemsa stained cell images, the proposed candidate based centromere detection algorithm was able to accurately localize 1220 centromere locations yielding a detection accuracy of 87%

Endophytic Fungal Species in Tropical Trees: A Review

Pathogenic fungi are common in forest ecosystems which cause diseases and sometimes death of plants, while some fungi live inside trees harmlessly without causing issues. Sometimes, plants benefit from the presence of those endophytic fungi, such as gaining resistance to environmental stresses, protection from harmful pathogens etc. Numerous studies have been conducted on such relationships between endophytic fungi and short-term agricultural crops. However, such studies are rare in the literature on tropical tree species which bear timber and non-timber values. This study illustrates the studies conducted on endophytic fungi in tropical trees and explores the potential use of such fungi for obtaining benefits

Solvation Properites of Supercritical Carbon Dioxide Using Chirped-Pulse Fourier-Transform Microwave Spectra of Carbon Dioxide / 1, 1-Difluoroethene (DFE) Mixtures

Supercritical carbon dioxide (sc-C02) is a highly utilized industrial substance identified as an excellent solvent and a surfactant, which is cheaper and less hazardous than other typical solvents. The higher solubility of fluorinated hydrocarbons than their hydrocarbon (HC) analogs is not well understood and the theory behind the microsolvation of sc-C02 cannot be fully explained with the existing chemical information. Microwave spectroscopy is a good method of identifying the structural arrangement of clusters made from fluorinated HCs and C02. I n this project, microwave scans of the four different mixtures of 1 , 1-difluoroethene (DFE) and C02 were studied and additionally a pure DFE scan was studied additionally. A chirped-pulse Fourier-transform (FTMW) microwave spectrometer was used to obtain the scans. The DFE and C02 clusters can be easily identified using microwave spectroscopy because DFE is a very polar molecule and C02 has an induced dipole moment respectively. The relative intensities of the peaks in the scans and the rotational constants were considered to identify the molecular clusters. Previously identified DFE I C02 dimer structures were helpful to predict the bigger structures manually. Apart from that, the ABCluster application was used to predict the bigger structures, as guessing stable structures in three dimensions becomes harder as the cluster becomes bigger. All the predicted and approximated structures were optimized using Gaussian09W. One spectrum was identified in the DFE I C02 scans, and after comparing the intensities and rotational constants, it was confirmed as a DFE I (C02)3 tetramer. In this structure, one C02 is located above the DFE plane, another C02 is located side of DFE and the other C02 is located top-above of the DFE. One spectrum was identified in pure DFE scan and it was confirmed as a (DFE)3 trimer. In that structure, two DFEs are facing each other invertedly and the third DFE is located above the first two DFEs. This study aims to identify the salvation shell C02 makes around DFE when it dissolves. Hence, the maximum number of C02 molecules binding to a DFE molecule needs to be identified. A parallel study is occurring with vinyl fluoride (VF) I C02 and these studies collectively provide information about the variation in the number of C02 molecules that bind as the number of fluorine atoms attached to the same HC analog is varied. In the future, MathCAD applications will be used to identify largely spaced fingerprint patterns to find other stable clusters present in the experiment. Also, 13C isotopic studies will be done to confirm and compare the identified current structures

A simple cleaning machine for mattress fibre

A simple low cost cleaning machine for mattree fibre was designed and manufactured by the coconut processing board in order to get rid of dust in dry mattree fibre. This machine is described with tables ro indicate how the particular design came to be considered the most suitable for the purpose. The conditions under which it should be operated to give the best results are indicated

Basic biosecurity manual for tilapia hatchery technicians in Bangladesh

With the onset of Tilapia Lake Virus (TiLV) outbreaks in several Asian countries, WorldFish, in collaboration with Bangladesh’s Department of Fisheries, has developed a program to improve biosecurity in the tilapia industry throughout the country. As the first step, a training program has been designed and conducted to train a group of specialists called Master Trainers on improving tilapia hatchery biosecurity. This manual is a result of that program. The Master Trainers will use this manual for training tilapia hatchery technicians countrywide on how to improve biosecurity in hatcheries