Elucidation of basal body and centriole functions in Chlamydomonas reinhardtii

In eukaryotic cells, basal bodies and their structural equivalents, centrioles, play essential roles. They are needed for the assembly of flagella or cilia as well as for cell division. Chlamydomonas reinhardtii provides an excellent model organism for the study of the basal body and centrioles. Genes for two new members of the tubulin superfamily are needed for basal body/centriole duplication. In addition, other genes that play roles in the duplication and segregation of basal bodies are discussed.     

Procom: a web-based tool to compare multiple eukaryotic proteomes

SUMMARY: Each organism has traits that are shared with some, but not all, organisms. Identification of genes needed for a particular trait can be accomplished by a comparative genomics approach using three or more organisms. Genes that occur in organisms without the trait are removed from the set of genes in common among organisms with the trait. To facilitate these comparisons, a web-based server, Procom, was developed to identify the subset of genes that may be needed for a trait. AVAILABILITY: The Procom program is freely available with documentation and examples at http://ural.wustl.edu/~billy/Procom/ CONTACT: billy@ural.wustl.edu.     

Impairment, time out of school, and time off from work after burns

Objective measurement of impairment after burns is important to patients, physicians, lawyers, and insurance companies. Even so, we could not find any references in the English literature describing how to objectively rate the physical impairment of burn survivors. The American Medical Association (AMA) has published the book Guides to Evaluation of Permanent Impairment, which is commonly used by surgeons to rate injuries. We decided to use this document to rate the impairment of burn patients. We studied patients who were treated at the University of Washington Burn Center during the years 1981, 1982, and 1983; survived the injury; were hospitalized 5 or more days or were skin grafted; and were followed until their condition was fixed (usually 12 months). This group included 325 patients. The mean age was 28.2 years and the mean total body surface area burned (TBSA) was 11.6 percent. We measured whole-man impairment (WMI) as described by the Guides to the Evaluation of Permanent Impairment. The mean whole-man impairment was 7.7 percent. In addition, we recorded time off from work and out of school after burns. The average time off from work was 12.7 weeks, and the average time out of school was 8.5 weeks. We conclude that the AMA publication can be used to rate burn patients and that the whole-man impairment of burn survivors is quite low if amputation, loss of range of motion, and nerve damage can be prevented.     

A Genetic Analysis of Suppressors of the Pf10 Mutation in Chlamydomonas Reinhardtii

A mutation at the PF10 locus of the unicellular green alga Chlamydomonas reinhardtii leads to abnormal cell motility. The asymmetric form of the ciliary beat stroke characteristic of wild-type flagella is modified by this mutation to a nearly symmetric beat. We report here that this abnormal motility is a conditional phenotype that depends on light intensity. In the absence of light or under low light intensities, the motility is more severely impaired than at higher light intensities. By UV mutagenesis we obtained 11 intragenic and 70 extragenic strains that show reversion of the pf10 motility phenotype observed in low light. The intragenic events reverted the motility phenotype of the pf10 mutation completely. The extragenic events define at least seven suppressor loci; these map to linkage groups IV, VII, IX, XI, XII and XVII. Suppressor mutations at two of the seven loci (LIS1 and LIS2) require light for their suppressor activity. Forty-eight of the 70 extragenic suppressors were examined in heterozygous diploid cells; 47 of these mutants were recessive to the wild-type allele and one mutant (bop5-1) was dominant to the wild-type allele. Complementation analysis of the 47 recessive mutants showed unusual patterns. Most mutants within a recombinationally defined group failed to complement one another, although there were pairs that showed intra-allelic complementation. Additionally, some of the mutants at each recombinationally defined locus failed to complement mutants at other loci. They define dominant enhancers of one another.     

The UNI3 Gene Is Required for Assembly of Basal Bodies of Chlamydomonas and Encodes δ-Tubulin, a New Member of the Tubulin Superfamily

We have cloned the UNI3 gene in Chlamydomonas and find that it encodes a new member of the tubulin superfamily. Although Uni3p shares significant sequence identity with α-, β-, and γ-tubulins, there is a region of Uni3p that has no similarity to tubulins or other known proteins. Mutant uni3–1 cells assemble zero, one, or two flagella. Pedigree analysis suggests that flagellar number in uni3–1 cells is a function of the age of the cell. The uniflagellate uni3–1 cells show a positional phenotype; the basal body opposite the eyespot templates the single flagellum. A percentage of uni3–1 cells also fail to orient the cleavage furrow properly, and basal bodies have been implicated in the placement of cleavage furrows in Chlamydomonas. Finally when uni3–1 cells are observed by electron microscopy, doublet rather than triplet microtubules are observed at the proximal end of the basal bodies. We propose that the Uni3 tubulin is involved in both the function and cell cycle-dependent maturation of basal bodies/centrioles.     

Variation in nuclear DNA base composition (mol % G + C) in three orders of marine green algae

Estimates of nuclear DNA base pair composition by determination of thermal denaturation temperatures (T_m) indicated guanine + cytosine (G + C) levels of 35–56% for 17 species of marine green algae. T_m values were found to be reproducible with coefficients of variation among samples and replicates of generally less than 1 percent. G + C % values in four species of Enteromorpha varied within a narrow range of 53–56%, whereas values for three species of Ulva showed substantially greater variation, ranging from 35–55%. Ulva fasciata collections from two geographically separate North Carolina sites had mean G + C composition of 44.8 and 35.6 respectively, suggesting that these populations may be genetically distinct. Enteromorpha linza, which has been treated as a species of Ulva, had a G + C composition of 53.2, typical of the Enteromorpha species investigated. Nuclear DNA base pair composition data for species of Cladophorales and Caulerpales are given as well.Center for Marine Science Research, UNC-W contribution No. 009.     

Inter- and intraspecific variation of nuclear DNA reassociation kinetics in the Gracilariales (Rhodophyta)

DNA reassociation kinetics were used to determine inter- and intraspecific variation in genome organization and complexities in species ofGracilaria andGracilariopsis. Results indicate the presence of three second order components corresponding to fast, intermediate and slow fractions. Repeated sequences varied from 13–95%. Three geographic populations ofGracilaria tikvahiae were similar with 13–27% repeated sequences.Gracilaria sp. cultivars G-1 and G-6 with 35% and 95% repeated sequences, respectively, were distinct from each other andG. tikvahiae. No pattern of genome organization and complexity was found which permitted a distinction betweenGracilaria andGracilariopsis. Comparison of the percent of unique and repetitive sequences (U/R) indicated a wide range of ratios, withGracilaria tikvahiae populations having the highest values (2.7–7.3) andGracilaria sp. cultivar G-6,G. blodgettii andGracilariopsis lemanieformis the lowest (0.05–1.80). Unique component complexities varied one order of magnitude, from 10⁸ forGracilaria takvahiae to 10⁷ forGracilaria sp. cultivar G-6,G. blodgettii andGracilariopsis lemanieformis. Information for genome size, organization and complexity is used to develop a nuclear genome profile forGracilaria blodgettii andGracilariopsis lemanieformis which are characterized by commercial grade agars having high gel strengths (> 700 g cm^?2) and elevated melting temperatures (99 °C).     

Nuclear genome characterization of the carrageenophyteHypnea musciformis (Rhodophyta)

DNA reassociation kinetics were used to determine nuclear genome organization and complexity in the carrageenophyteHypnea musciformis (Gigartinales, Rhodophyta). Results indicate the presence of three second order components corresponding to fast (2%), intermediate (33%) and slow (65%) fractions. Microspectrophotometry with the DNA-localizing fluorochrome DAPI confirmed ploidy level differences in the gametophytic and tetrasporophytic phases. Elevated (endopolyploid) nuclear DNA levels were observed in both gametophytic and cystocarpic tissue. Comparison of mean nuclear DNA (If) values to chicken erthrocytes (RBC) resulted in an estimate of 0.22 pg/2 C genome forHypnea musciformis. Karyological studies using aceto-orcein revealed a chromosome complement of five bivalents during diakinesis of tetraspore mother cells.     

Piloting the One Health Systems Mapping and Analysis Resource Toolkit in Indonesia

As a global network, countries are being asked to meet goals set forth in the Global Health Security Agenda (GHSA) for a workforce capable of effective and efficient prevention, detection and response to infectious disease threats. There is great need for a cross-sectoral workforce that can innovate and problem-solve. To achieve GHSA goals, countries need a way to visualize their existing system, identify opportunities for improvement, and achieve improved cross-sectoral interactions. The One Health Systems Mapping and Analysis Resource Toolkit (OH-SMART) was successfully piloted in West Sumatra, Indonesia, and was used to enhance multi-agency collaboration around infectious disease outbreaks and proved to be an adaptable, scalable process requiring minimal resources. The authors present OH-SMART as a potential tool to help countries analyze their existing health system and create relevant action steps to improve cross-sectoral collaborations.