Centriole as microtubule-organizing centers for marginal bands of molluscan erythrocytes

The erythrocytes of blood clams (arcidae) are flattened, elliptical, and nucleated. They contain elliptical marginal bands (MBs) of microtubules, each physically associated with a pair of centrioles marginal bands (MBs) of microtubles, each physically associated with a pair of centrioles (Cohen, W., and I. Nemhauser, 1980, J. Cell Biol., 86:286-291). The MBs were found to be cold labile in living cells, disappearing within 1-2 h at 0 degrees C. After the cells had been rewarmed for 1-2 h, continuous MBs with associated centrioles were once again present. Time-course studies utilizing phase contrast, antitubulin immunofluorescence, and electron microscopy of cytoskeletons prepared during rewarming revealed structural evidence of centriole participation in MB reassembly. At the earliest stage of reassembly, a continuous MB was not present. Instead, relatively short and straight microtubules focused on a pointed centriolar “pole,” and none were present elsewhere in the cytoskeleton. Thin continuous MBs then formed, still pointed in the centriolar region. Subsequently, the MBs regained ellipticity, with their thickness gradually increasing but not reaching that of controls even after several hours of rewarming. At these later time points, microtubules still radiated from the centrioles and joined the MBs some distance away. In the presence of 0.1 mM colchicines, MB reassembly was arrested at the pointed stage. Electron microscopic observations indicate that pericentriolar material is involved in microtubule nucleation in this system, rather than the centriolar triplets directly. The results suggest a model in which the centrioles and associated material nucleate assembly and growth of microtubules in diverging directions around the cell periphery. Microtubules of opposite polarity would then pass each other at the end of the cell distal to the centrioles, with continued elongation eventually closing the MB ellipse behind the centriole pair.     

X-ray sterilization of biopharmaceutical manufacturing equipment—Extractables profile of a film material and copolyester Tritan™ compared to gamma irradiation

The biopharmaceutical industry gains enormous flexibility in production processes by using sterilized preassembled single-use devices. Gamma irradiation is an established sterilization technology that may be restricted in the future by the availability of ⁶⁰Co as irradiation source and irradiation capacities. X-ray technology is considered an alternative type of radiation for sterilizing SU equipment. In the context of extractables and leachables—one concern connected with the use of single-use process equipment—the effect of X-ray irradiation on the extractables profile of the materials needs to be compared to established gamma irradiation to qualify this alternative technology. An approach is presented to obtain robust and comprehensive extractables data for materials used in SU devices after sterilization either using X-ray or gamma irradiation. A careful selection of the test items and the test design allows a one-to-one comparison of data obtained from a combination of orthogonal analytical techniques. The extractables of a modern SU film material and the copolyester Tritan™ are evaluated. The data presented allow a risk evaluation on the safety of this new sterilization modality for biopharmaceutical applications. It is demonstrated that the extractables profile of a polymer is not affected by the type of irradiation used for sterilization.     

Somatotopic representation of action words in human motor and premotor cortex

Since the early days of research into language and the brain, word meaning was assumed to be processed in specific brain regions, which most modern neuroscientists localize to the left temporal lobe. Here we use event-related fMRI to show that action words referring to face, arm, or leg actions (e.g., to lick, pick, or kick), when presented in a passive reading task, differentially activated areas along the motor strip that either were directly adjacent to or overlapped with areas activated by actual movement of the tongue, fingers, or feet. These results demonstrate that the referential meaning of action words has a correlate in the somatotopic activation of motor and premotor cortex. This rules out a unified "meaning center" in the human brain and supports a dynamic view according to which words are processed by distributed neuronal assemblies with cortical topographies that reflect word semantics.     

High sero-prevalence of caseous lymphadenitis identified in slaughterhouse samples as a consequence of deficiencies in sheep farm management in the state of Minas Gerais, Brazil

Background

Multiple congenital ocular anomalies (MCOA) syndrome is a hereditary congenital eye defect that was first described in Silver colored Rocky Mountain horses. The mutation causing this disease is located within a defined chromosomal interval, which also contains the gene and mutation that is associated with the Silver coat color (PMEL17, exon 11). Horses that are homozygous for the disease-causing allele have multiple defects (MCOA-phenotype), whilst the heterozygous horses predominantly have cysts of the iris, ciliary body or retina (Cyst-phenotype). It has been argued that these ocular defects are caused by a recent mutation that is restricted to horses that are related to the Rocky Mountain Horse breed. For that reason we have examined another horse breed, the Icelandic horse, which is historically quite divergent from Rocky Mountain horses.

Results

We examined 24 Icelandic horses and established that the MCOA syndrome is present in this breed. Four of these horses were categorised as having the MCOA-phenotype and were genotyped as being homozygous for the PMEL17 mutation. The most common clinical signs included megaloglobus, iris stromal hypoplasia, abnormal pectinate ligaments, iridociliary cysts occasionally extending into the peripheral retina and cataracts. The cysts and pectinate ligament abnormalities were observed in the temporal quadrant of the eyes. Fourteen horses were heterozygous for the PMEL17 mutation and were characterized as having the Cyst-phenotype with cysts and occasionally curvilinear streaks in the peripheral retina. Three additional horses were genotyped as PMEL17 heterozygotes, but in these horses we were unable to detect cysts or other forms of anomalies. One eye of a severely vision-impaired 18 month-old stallion, homozygous for the PMEL17 mutation was examined by light microscopy. Redundant duplication of non-pigmented ciliary body epithelium, sometimes forming cysts bulging into the posterior chamber and localized areas of atrophy in the peripheral retina were seen.

Conclusions

The MCOA syndrome is segregating with the PMEL17 mutation in the Icelandic Horse population. This needs to be taken into consideration in breeding decisions and highlights the fact that MCOA syndrome is present in a breed that are more ancient and not closely related to the Rocky Mountain Horse breed.     

Amplification of noncoding chloroplast DNA for phylogenetic studies in lycophytes and monilophytes with a comparative example of relative phylogenetic utility from Ophioglossaceae

Noncoding DNA sequences from numerous regions of the chloroplast genome have provided a significant source of characters for phylogenetic studies in seed plants. In lycophytes and monilophytes (leptosporangiate ferns, eusporangiate ferns, Psilotaceae, and Equisetaceae), on the other hand, relatively few noncoding chloroplast DNA regions have been explored. We screened 30 lycophyte and monilophyte species to determine the potential utility of PCR amplification primers for 18 noncoding chloroplast DNA regions that have previously been used in seed plant studies. Of these primer sets eight appear to be nearly universally capable of amplifying lycophyte and monilophyte DNAs, and an additional six are useful in at least some groups. To further explore the application of noncoding chloroplast DNA, we analyzed the relative phylogenetic utility of five cpDNA regions for resolving relationships in Botrychium s.l. (Ophioglossaceae). Previous studies have evaluated both the gene rbcL and the trnL(UAA)-trnF(GAA) intergenic spacer in this group. To these published data we added sequences of the trnS(GCU)-trnG(UUC) intergenic spacer + the trnG(UUC) intron region, the trnS(GGA)-rpS4 intergenic spacer+rpS4 gene, and the rpL16 intron. Both the trnS(GCU)-trnG(UUC) and rpL16 regions are highly variable in angiosperms and the trnS(GGA)-rpS4 region has been widely used in monilophyte phylogenetic studies. Phylogenetic resolution was equivalent across regions, but the strength of support for the phylogenies varied among regions. Of the five sampled regions the trnS(GCU)-trnG(UUC) spacer+trnG(UUC) intron region provided the strongest support for the inferred phylogeny.