Distinct Division Research Articles

High-Resolution Genotyping of Listeria monocytogenes by Fluorescent Amplified Fragment Length Polymorphism Analysis Compared to Pulsed-Field Gel Electrophoresis, Random Amplified Polymorphic DNA Analysis, Ribotyping, and PCR–Restriction Fragment Length Polymorphism Analysis

The purpose of this study was to evaluate fluorescent amplified fragment length polymorphism (AFLP) analysis for the inter- and intraspecies differentiation of a collection of 96 strains of Listeria monocytogenes and 10 non–L. monocytogenes strains representing six other Listeria species of different origin. The AFLP technique was compared with three other molecular typing methods—ribotyping, random amplified polymorphic DNA analysis (RAPD), and pulsed-field gel electrophoresis (PFGE)—in terms of discriminatory ability. PCR–restriction fragment length polymorphism was included for virulence gene allele characterization. The 96 L. monocytogenes strains were divided into two major clusters by AFLP fingerprinting at a similarity level of 82% in concordance with the results of PFGE, RAPD, and ribotyping. One main cluster consisted of all of the 24 L. monocytogeneshly allele 1 strains, while another main cluster consisted of all of the 72 L. monocytogeneshly allele 2 strains. This indicates the existence of two distinct phylogenetic divisions. Isolates of the remaining Listeria species were not included in the clusters. AFLP, PFGE, and RAPD typing were highly discriminatory methods, with discrimination (D) indices of 0.974, 0.969, and 0.954, respectively, whereas ribotyping had a lower D index of 0.874. AFLP, PFGE, and RAPD typing showed some level of agreement in terms of strain grouping and differentiation. However, all three methods subdivided types of strains grouped by the other methods. Isolates with identical DNA profiles were distributed across the spectrum of origin. It was not possible to associate certain types with specific food sectors or clinical cases, which is indicative of the spread of L. monocytogenes clones across species. Overall, AFLP fingerprinting was suitable for the high-resolution genotyping of L. monocytogenes and had an equally high or higher differentiation power compared to PFGE or RAPD typing.

Seasonal variability in whale encounters in the Western Antarctic Peninsula

Cetacean sighting surveys were conducted as part of nine multidisciplinary research cruises over late summer, autumn and winter of 2 years (2001–2003) during the Southern Ocean Global Ocean Ecosystems (SO GLOBEC) program. Seaice cover differed markedly between years, with apparent effects on cetacean distribution. No ice was present until late June in 2001, while the previous winter sea ice never fully retreated (430% cover) during the 2002 or 2003 summer, thus increasing the proportion of thicker and more complex ice, including multi-year floes. Humpback (237 sightings; 537 individuals) and minke (103 sightings: 267 individuals) whales were the most commonly detected species. Data from seven comparable cruises were used to identify habitat for minke and humpback whales over five geographically distinct spatial divisions in the study area. In all years, both species were predominantly found in near coastal habitat, particularly in the fjords where complex habitat likely concentrated prey. In 2002 and 2003 the presence of sea ice provided additional feeding habitat, and the numbers of minkes (in winter) and humpbacks (late summer and autumn) in the area doubled compared with 2001. Humpbacks in particular were concentrated at the ice boundaries during late summer and autumn, while minke numbers increased in the winter that followed and occupied ice-covered areas along the entire shelf edge. Important resource sites for these species are mainly located in near-coastal areas and are used in all years, but when ice margins exist and intersect with resource sites they attract much larger numbers of animals due to the dynamics between sea ice and prey. r 2004 Elsevier Ltd. All rights reserved.

A cellular growth model for root tips

Growth of the root tip is modeled using a one-dimensional string of cells. Each cell is characterized by three distinct phases, division, elongation-only or maturity. In this model two hypothetical phytohormones, one produced at the root tip and the other at the shoot, determine the behavior of the cell, and therefore the growth of the entire tip. While the division rate is taken to be a step function of the string coordinate, the growth rate of each cell is assumed to be piecewise linear and composed of linear functions of cell length. Thereafter, suitable operators for the calculation of the velocity and relative growth rate distributions are given. The results of the model are finally compared to measurements of Arabidopsis thaliana, Nicotiana tabacum and Pisum sativum roots.

Editing and the Crisis of Open Source

Editing and the Crisis of Open Source

Racial politics in residential segregation studies

Most research about race has been influenced by values of one sort or another. This started with the inception of race as a biological category. Cognitive values about race were concerned with the worth of distinctive taxonomic divisions, and political values about it were concerned with the moral, aesthetic, and political meanings of these human distinctions. The presence of cognitive and non‐cognitive values in contemporary social science concerning race is no less present or important. The role of racial politics is exposed in the debate over the nature of contemporary residential housing patterns, as well as in examinations of the methods and measures of segregation research. Such examinations uncover not only a sociology of the segregation studies, but also certain values about race and segregation. This leads us to richer explanations, given our public political desires, than we would have without those values.

The holy profane: religion in black popular music

Winner of the 2004 ARSC Award for Best Research in Recorded Rock, Rhythm & Blues or Soul The Holy Profane explores the strong presence of religion in the secular music of twentieth-century African American artists as diverse as Rosetta Tharpe, Sam Cooke, Stevie Wonder, Marvin Gaye, Earth, Wind & Fire, and Tupac Shakur. Analyzing lyrics and the historical contexts which shaped those lyrics, Teresa L. Reed examines the link between West-African musical and religious culture and the way African Americans convey religious sentiment in styles such as the blues, rhythm and blues, soul, funk, and gangsta rap. She looks at Pentecostalism and black secular music, minstrelsy and its portrayal of black religion, the black church, crossing from gospel to R&B, images of the black preacher, and the salience of God in the rap of Tupac Shakur. Traditionally, west European culture has drawn distinct divisions between the secular and the sacred in music. Liturgical music belongs in church, not on pop radio, and artists who fuse the two are guilty of sacrilege. In the West-African worldview, however, both music and the divine permeate every imaginable part of life-so much so that concepts like sacred and secular were entirely foreign to African slaves arriving in the colonies. The Western influence on African Americans eventually resulted in more polarization between these two musical forms, and black musicians who grew up singing in church were often lamented as hellbound once they found popular success. Even these artists, however, never completely left behind their West-African musical ancestry. Reed's exploration of this trend in African American music connects the work of today's artists to their West-African ancestry-a tradition that over two-hundred years of Western influence could not completely stamp out.

Mode of morphological differentiation in the Latitarsi-ground beetles(Coleoptera, Carabidae) of the world inferred from a phylogenetic tree of mitochondrial ND5 gene sequences.

The Latitarsi is one large division of the subtribe Carabina (subfamily Carabinae, family Carabidae), and has been considered as a discrete morphological group consisting of 17 genera. The phylogenetic relationships and evolutionary pattern of the Latitarsi ground beetles have been investigated by analyzing mitochondrial NADH dehydrogenase subunit 5 (ND5) gene sequences. The phylogenetic tree suggests that the Latitarsi members do not form a single cluster, i.e., not monophyletic and at least 16 lineages belonging to the so-called Latitarsi emerged at about the same time of the Carabina radiation together with the members of other divisions. This suggests that these lineages (A, B, C, H, L, N, O, P, Q, R, S, T, U, V, W and X in Fig. 2a) may be treated each as a phylogenetically distinct division equivalent to other divisions. The group with bootstrap value of more than 80 percent has been considered as a single lineage (division) with two exceptions, V and X. The independency of each lineage has been assumed by the traditional morphology as well as a single clustering on the trees constructed by independent methods, unchanged topology by replacement of outgroups, etc. Generally speaking, the members in a single lineage are geographically linked. Many phylogenetic lineages are composed of a single or only a few species without conspicuous morphological differentiation. In contrast to such a "silent morphological evolution", a remarkable morphological differentiation occasionally took place in several lineages.

Harry Potter, Inc.

Harry Potter, Inc.

PHYLOGENY OF THE GENUS COLEOCHAETE (COLEOCHAETALES, CHAROPHYTA) AND RELATED TAXA INFERRED BY ANALYSIS OF THE CHLOROPLAST GENE rbcL1

The genus Coleochaete Bréb. is considered to be a key taxon in the evolution of green algae and embryophytes (land plants), but only a few of the approximately 15 species have been studied with molecular phylogenetic methods. We report here the sequences of the gene rbcL from six new cultures of Coleochaete and two of Chaetosphaeridium Klebahn. These sequences were combined with 32 additional sequences, and phylogenetic analyses were performed with maximum likelihood, distance optimality, and parsimony methods. Important subgroups within Coleochaete include two primary lineages, one marked by fully corticated zygotes and the other by naked or weakly corticated zygotes. In the first lineage there is a subclade with tightly joined filaments and distinctive (“T‐shaped”) cell division, an assemblage of strains that resembles the endophytic species Coleochaete nitellarum Jost, and a clade with loosely joined filaments and “Y‐shaped” cell divisions. Consistent with recent multigene phylogenies, these analyses support the monophyly of the Coleochaetales, place the Charales as the sister taxon to land plants, and indicate that Chaetosphaeridium is far more closely related to Coleochaete than to Mesostigma Lauterborn.

Branching patterns of rabbit oculomotor and trochlear nerves demonstrated by Sihler's stain technique

A modified Sihler's stain technique was used to visualize the branching patterns of oculomotor and trochlear nerves. The levator palpebrae, superior rectus, inferior rectus, medial rectus, inferior oblique, superior oblique and tensor trochlea muscles were isolated from the eyes of normal rabbits and processed using modified Sihler's technique. The distributions and terminal ramifications of the oculomotor and trochlear nerves were observed. Two distinct divisions and terminal branches of the oculomotor nerve were shown in detail together with the trochlear nerve distribution. The application of Sihler's technique enables researchers to trace nerve branching within relatively transparent muscles, whereas the nerve fibers are counterstained and clearly visible. This technique could be useful for detailed studies of the motor control of extraocular muscles.

The State of Family-Owned Businesses in the Yukitsumugi Industry and Associated Changes

A study was conducted on the state of family-owned businesses and associated changes by examining the Yukitsumugi (a pongee produced in Yuki) industry which has relied heavily on family labor. The results are summarized as follows:Yukitsumugi production has changed considerably over the years. When it was being produced as a side business of extended farm families, there was a distinct division of family labor, including housework and child care. At this time, there were many self-employed hataya, or textile weavers.However, beginning in the 1960s, the heads of an increasing number of Yukitsumugi households began working in offices and living away from their parents and in-laws. In such families, it became more difficult to run businesses that included the production of pongee. What was once an industry that had a distinct family-based division of labor now became the domain not of work-at-home farm wives, but of wage earners in the families of office workers. This was due to the increase in higher-grade schooling and the diversification of job opportunities for women.This trend in the production area was necessary to produce high-class pongee. In the Yuki region, high-quality production was achieved by hataya who combined traditional techniques.However, this type of production started to become much less consistent than that of the old-time farm families. Fewer and fewer skilled workers were employed in the industry, making it increasingly difficult to produce high-quality materials.Since the 1980s, Yukitsumugi production has been steadily declining as workers retire or leave for other jobs without having a successor to take their place. This has had grave consequences for the industry, especially in the reorganization of the production structure.

The Distribution and Morphological Characteristics of Serotonergic Cells in the Brain of Monotremes

The distribution and cellular morphology of serotonergic neurons in the brain of two species of monotremes are described. Three clusters of serotonergic neurons were found: a hypothalamic cluster, a cluster in the rostral brainstem and a cluster in the caudal brainstem. Those in the hypothalamus consisted of two groups, the periventricular hypothalamic organ and the infundibular recess, that were intimately associated with the ependymal wall of the third ventricle. Within the rostral brainstem cluster, three distinct divisions were found: the dorsal raphe nucleus (with four subdivisions), the median raphe nucleus and the cells of the supralemniscal region. The dorsal raphe was within and adjacent to the periaqueductal gray matter, the median raphe was associated with the midline ventral to the dorsal raphe, and the cells of the supralemniscal region were in the tegmentum lateral to the median raphe and ventral to the dorsal raphe. The caudal cluster consisted of three divisions: the raphe obscurus nucleus, the raphe pallidus nucleus and the raphe magnus nucleus. The raphe obscurus nucleus was associated with the dorsal midline at the caudal-most part of the medulla oblongata. The raphe pallidus nucleus was found at the ventral midline of the medulla around the inferior olive. Raphe magnus was associated with the midline of the medulla and was found rostral to both the raphe obscurus and raphe pallidus. The results of our study are compared in an evolutionary context with those reported for other mammals and reptiles.

Information Technology, Gender Segmentation and the Relocation of Back Office Employment: The Growth of the Teleservices Sector in Ireland

The movement of routine back office activities from the central business districts of metropolitan regions in advanced economies to remote locations is leading to a distinctive global division of labour in office employment. While facilitated by the development of information and communication technologies, this process of relocation is primarily driven by the desire to reduce operating costs, mainly by moving to sources of cheap female workers. This reflects a classic gender segmentation process in patriarchal societies whereby back office work is mainly done by women and, accordingly, involves relatively low levels of remuneration. This provides direct parallels with the offshoring of routine manufacturing work associated with the new international division of labour. Ireland has been to the forefront in acting as a host for internationally-mobile routine office work, initially involving mainly data processing and, more recently, teleservices. As elsewhere, teleservices employment in Ireland is characterized by a combination of female predominance, low pay, difficult working conditions and high turnover rates. However, the Irish teleservices sector is unusual in its foreign language requirement, the high education levels of workers and its concentration in a prosperous metropolitan location. The resultant labour shortages, combined with growing use of Internet-based business-to-consumer transactions, are likely to place the sustainability of the sector under increasing pressure. Plans to upgrade the types of back office functions being located in Ireland may pose further challenges for women workers due to male dominance of the higher-level jobs involved.

Heterotrimeric G Proteins Direct Two Modes of Asymmetric Cell Division in the Drosophila Nervous System

In Drosophila, distinct mechanisms orient asymmetric cell division along the apical-basal axis in neuroblasts and along the anterior-posterior axis in sensory organ precursor (SOP) cells. Here, we show that heterotrimeric G proteins are essential for asymmetric cell division in both cell types. The G protein subunit Gαi localizes apically in neuroblasts and anteriorly in SOP cells before and during mitosis. Interfering with G protein function by Gαi overexpression or depletion of heterotrimeric G protein complexes causes defects in spindle orientation and asymmetric localization of determinants. Gαi is colocalized and associated with Pins, a protein that induces the release of the βγ subunit and might act as a receptor-independent G protein activator. Thus, asymmetric activation of heterotrimeric G proteins by a receptor-independent mechanism may orient asymmetric cell divisions in different cell types.

Cell compartmentalisation in planctomycetes: novel types of structural organisation for the bacterial cell.

The organisation of cells of the planctomycete species Pirellula marina, Isosphaera pallida, Gemmata obscuriglobus, Planctomyces maris and "Candidatus Brocadia anammoxidans" was investigated based on ultrastructure derived from thin-sections of cryosubstituted cells, freeze-fracture replicas, and in the case of Gemmata obscuriglobus and Pirellula marina, computer-aided 3-D reconstructions from serial sections of cryosubstituted cells. All planctomycete cells display a peripheral ribosome-free region, termed here the paryphoplasm, surrounding the perimeter of the cell, and an interior region including any nucleoid regions as well as ribosome-like particles, bounded by a single intracytoplasmic membrane (ICM), and termed the pirellulosome in Pirellula species. Immunogold labelling and RNase-gold cytochemistry indicates that in planctomycetes all the cell DNA is contained wholly within the interior region bounded by the ICM, and the paryphoplasm contains no DNA but at least some of the cell's RNA. The ICM in Isosphaera pallida and Planctomyces maris is invaginated such that the paryphoplasm forms a major portion of the cell interior in sections, but in other planctomycetes it remains as a peripheral zone. In the anaerobic ammonium-oxidising ("anammox" process) chemoautotroph "Candidatus Brocadia anammoxidans" the interior region bounded by ICM contains a further internal single-membrane-bounded region, the anammoxosome. In Gemmata obscuriglobus, the interior ICM-bounded region contains the nuclear body, a double-membrane-bounded region containing the cell's nucleoid and all genomic DNA in addition to some RNA. Shared features of cell compartmentalisation in different planctomycetes are consistent with the monophyletic nature of the planctomycetes as a distinct division of the Bacteria. The shared organisational plan for the planctomycete cell constitutes a new type not known in cells of other bacteria.

Cell migration to the anterior and posterior divisions of the granule cell layer of the accessory olfactory bulb of adult opossums

To test the hypothesis that differential addition of new cells occurs in the two functionally distinct divisions of the accessory olfactory bulb (AOB), the addition of bromodeoxyuridine-labeled cells was analyzed in the anterior and posterior subdivisions of the AOB as a function of post-injection survival time (0–11 days). One week postinjection, an increase of cells was detected in the granule layer but not in the glomerular or mitral/tufted cell layers. No evidence for differential addition of cells to the anterior and posterior divisions was observed.

Unique nucleoid structure during cell division of Thermococcus kodakaraensis KOD1

The nucleoid structure and the partition in the hyperthermophilic archaeon Thermococcus kodakaraensis KOD1 were observed by a combination of phase-contrast microscopy and fluorescence microscopy. The nucleoids occurred as rounded fluorescent foci centrally located in the cells and as differences in fluorescence intensity between exponential and stationary phases. The cellular space occupied by the nucleoid in the stationary phase was larger than that in the exponential phase. Various shapes of nucleoid in the exponential-phase cells were observed, indicating that nucleoid separation was processed under cell cycle control. The number of cells which showed distinctive division stages was counted and the proportions of dividing cells were determined. About half of the observed cells were in the replication stage. More than 40% of the counted cells possessed a fully replicated but not separated form of nucleoid. Only 8% of the total cells clearly showed visible constriction. These results suggested that the post-replication period before cell division was relatively as long as the eucaryal gap period (G2); however, the period of visible cell constriction was almost the same as that of the bacteria.

Unique Nucleoid Structure during Cell Division of Thermococcus kodakaraensis KOD1.

The nucleoid structure and the partition in the hyperthermophilic archaeon Thermococcus kodakaraensis KOD1 were observed by a combination of phase-contrast microscopy and fluorescence microscopy. The nucleoids occurred as rounded fluorescent foci centrally located in the cells and as differences in fluorescence intensity between exponential and stationary phases. The cellular space occupied by the nucleoid in the stationary phase was larger than that in the exponential phase. Various shapes of nucleoid in the exponential-phase cells were observed, indicating that nucleoid separation was processed under cell cycle control. The number of cells which showed distinctive division stages was counted and the proportions of dividing cells were determined. About half of the observed cells were in the replication stage. More than 40% of the counted cells possessed a fully replicated but not separated form of nucleoid. Only 8% of the total cells clearly showed visible constriction. These results suggested that the post-replication period before cell division was relatively as long as the eucaryal gap period (G2); however, the period of visible cell constriction was almost the same as that of the bacteria.

Crustal structure of central and northern Iceland from analysis of teleseismic receiver functions

We present results from a teleseismic receiver function study of central and northern Iceland, carried out during the period 1995–1998. Data from eight broad-band seismometers installed in the SIL network operated by the Icelandic Meteorological Office were used for analysis. Receiver functions for each station were generated from events for a wide range of backazimuths and a combination of inversion and forward modelling was used to infer the crustal structure below each station. The models generated show a considerable variation in the nature and thickness of the crust across Iceland. The thinnest crust (20–21 km) is found in the northern half of the Northern Volcanic Zone approximately 120 km north of the centre of the Iceland mantle plume. Thicker crust (24–30 km) is found elsewhere in northern and central Iceland and the thickest crust (37 km) is found close to the plume centre. Velocity–depth profiles show a distinct division of the crust into two main sections, an upper high-velocity-gradient section of thickness 2–8 km and a lower crustal section with small or zero overall velocity gradient. The thickness of the upper crust correlates with the tectonic structure of Iceland; the upper crust is thickest on the flanks of the northern and central volcanic rift zones and thinnest close to active or extinct central volcanoes. Below the Krafla central volcano in northeastern Iceland the receiver function models show a prominent low-velocity zone at 10–15 km depth with minimum shear wave velocities of 2.0–2.5 km s−1. We suggest that this feature results from the presence of partially molten sills in the lower crust. Less prominent low-velocity zones found in other regions of Iceland may arise from locally high temperatures in the crust or from acidic intrusive bodies at depth. A combination of the receiver function results and seismic refraction results constrains the crustal thickness across a large part of Iceland. Melting by passive decompression of the hot mantle below the rift zone in northern Iceland forms a crust of thickness ∼20 km. In contrast, the larger crustal thickness below central Iceland probably arises from enhanced melt production due to active upwelling in the plume core.

Craft versus industry: the division of labour in European housing construction

Two distinct divisions and concepts of labour are apparent from an analysis of social housebuilding sites in the UK, Germany and the Netherlands: the craft form, based on controlling the output of labour; and the industry form, based on the quality of labour input. These are associated with different work processes, skills and training, and also different levels of mechanization and component prefabrication. In the UK, which is craft-based, low levels of mechanization and prefabrication were found compared with Germany and the Netherlands, and the range of activities for the separate trades in assembling superstructure elements was simpler. Labourers are distinct from craftsmen and remain a significant group. Skills are narrow and training provision low. A high proportion of the labour force remains self-employed, under labour-only subcontractors, working to price or output. In comparison, in Germany and the Netherlands labour is employed directly and work processes are more complex, with more specialisms at the interfaces. The division of labour is industry-wide, training provision is extensive, and skills are broad and integrated into the grading structure. Greater speed, higher productivity and lower levels of supervision are associated with industry-wide systems compared with traditional craft forms.