Original Division Research Articles

MICHAL BIRAN, Qaidu and the Rise of the Independent Mongol State in Central Asia (Richmond, Surrey, U.K.: Curzon, 1997). Pp. 208. $75.00 cloth.

Michal Biran fills an important gap in research on the 13th-century Mongol empire with her recent study of Qaidu (1236–1301), a great-grandson of Chinggis Khan and champion of the house of Ögödei. Characterizing Qaidu as a pragmatist, not an “ideological warrior” (p. 107), she challenges the conventional view that he was one of the quintessential defenders of nomadic values against the sedentarizing ethos of other Mongol rulers, and that he claimed the office of qa⊂an (supreme Mongol overlord). The work argues that his long struggle with Qubilai and his ruling career in Central Asia had two main goals: to restore to the Ögödeid ulus its rightful territory according to the original division of the empire by Chinggis and to secure the political and economic viability of that territory. It concludes that Qaidu did not aspire to become the qa⊂an but played a crucial role in the emergence of an independent Chaghadaid khanate in the early 14th century.

The deep pectoral muscle flap in the cat: its vascular supply and potential use

SummaryThe vascular anatomy of the deep pectoral muscle in the cat was defined by contrast radiography of twelve deep pectoral muscles from six feline cadavers. The deep pectoral, muscle in the cat was found to have a type V vascular pattern with a dominant pedicle based on the lateral thoracic artery, with a contribution from the external thoracic artery, and secondary segmental pedicles arising from the internal thoracic artery, with numerous anastomoses between these two vascular fields. Following division of the sternal origin and elevation of the muscle flap, perfusion of the entire muscle from the dominant pedicle was identified. Transposition of the muscle flap within a wide arc of rotation was possible to include the chest wall, sternum, axilla and medial forelimb. This study demonstrates the potential suitability of the deep pectoral muscle flap for use in reconstructive surgery.The feline deep pectoral muscle has a type V vascular pattern, with a dominant pedicle based on the lateral thoracic artery, with a contribution from the external thoracic artery, and secondary segmental pedicles arising from the internal thoracic artery A clinically useful flap, supplied by the dominant pedicle, may be developed by incising the sternal origin of the muscle.

Linear ultrafilters

Let X be a k-vector space, and U a maximal proper filter of subspaces of X. Then the ring of endomorphisms of X that are “continuous” with respect to U modulo the ideal of those that are “trivial” with respect to U forms a division ring E(U). (These division rings can also be described as the endomorphism rings of the simple left End(X)-modules.) We study this and the dual construction, based on maximal cofiIters of subspaces of X, in particular, the relation between the constructed division rings and the original field or division ring k. We end by examining a more general construction in which X is a module over a general ring, given with both a filter and a cofilter of submodules.

THE USE OF MORPHOGENIC SUSPENSION CULTURES FOR THE DEVELOPMENT OF A PROTOPLAST REGENERATION SYSTEM IN LILY

The present study reports data on the development of a protoplast regeneration procedure in lily. Established morphogenic suspension cultures were obtained from callus cultures induced on mature embryos from crosses between cultivars of L. longiflorum. The effect on the frequency of protoplast division and microcolony formation of preculture conditions and origin of suspension cultures, composition of the protoplast isolation and culture media, anti-oxidants, an ethylene inhibitor, fetal calf serum, conditioned medium or a feeder culture and culture conditions are discussed.

Structural diversity in (vesicular)-arbuscular mycorrhizal symbioses.

This review describes diversity in the structure of (vesicular)-arbuscutar (VA) mycorrhizas, i.e. endomycorrhizas formed by Glomalean fungi. In particular, we consider the extent in the plant kingdom of the two classes first described by Gallaud (1905). These are: (1) the Arum-type, defined on the basis of an extensive intercellular phase of hyphai growth in the root cortex and development of terminal arbuscules on intracellular hyphai branches; (2) the Paris-type, defined by the absence of the intercellular phase and presence of extensive intracellular hyphai coils. Arbuscules are intercalary structures on the coils. However, there have been many reports that in Paris-types arbuscules are relatively few in numbers, small, or absent altogether. A survey of the literature has revealed that Paris-types occur more frequently in the plant kingdom than Arum-types and predominate in ferns, gymnosperms and many wild angiosperms. The cultivated herbs that are the subject of much experimental work are mostly Arum-types. Although evidence is still limited, there are differences at the family level. In 41 angiosperm families there are records of only Poris-type VA mycorrhizas and in 30 families records of only Arum-types. Another 21 families have examples of both classes, or intermediates between them. Accordingly, we consider whether the original division into two classes is still useful. We conclude that it is when considering the physiology of the symbiosis and especially the issue of whether different fungus/host interfaces have specialized roles in transfer of inorganic nutrients and organic carbon between the partners, if there is no such specialization between hyphai coils and arbuscules, then the latter might not be necessary1 for the function of Paris-types. This would account for reports of the infrequency or absence of arbuscules in this class. The control exerted on structures by the genomes of host and fungus, and possible reasons (anatomical and physiological) for the existence of the VA mycorrhizal structures, are discussed. The presence or absence of extensive intercellular spaces and differences in the wall structure of cortical cells might be particularly important in determining which type of VA mycorrhiza is formed. CONTENTS Summary 373 I. Introduction: Arum-types and Pom-types 374 II. Possible functional implications 375 III. Extent of the two classes in the plant kingdom 377 IV. Is the distinction between classes useful? 383 V. The structural basis 383 VI. The role of the fungal genome 384 VII. Physiology revisited 384 VIII. Conclusions 385 Acknowledgements 386 References 386.

Gendered Exclusion: Domesticity and Dependence in Bengal

In Western Europe, industrialization brought far-reaching changes in the family-household system by separating the household from the workplace. Factories, especially, took work away from home and eroded the integrity of the household. The spatial separation between the household and the workplace became the foundation for a conceptual separation between the community and the market. Families were separated from trades, consumption from production, women's activities from men's. These separations, often expressed in the generalized formula of a “private-public” divide, have underscored a thoroughgoing gender division of labour far beyond the original divisions supposed to be rooted in biological reproduction. In industrialized Europe, the working-class household's needs could not be met from the combined economic activities of its members: men, women and children. Rather, the daily bread was to be “won” by individual wage earners and clearly the breadwinners were to be men. In contrast, the home became the site of women's reproductive activities devoid of assignable exchange value. Wives' and daughters' unpaid work was increasingly underwritten by family ideology and was eventually to be covered by the “family wage” paid to husbands and fathers.

Formation of branched plasmodesmata in regenerating Solanum nigrum-protoplasts

During the early stages of culture, discontinuous branched half-plasmodesmata were found randomly scattered in the newly formed outer cell walls of regenerating Solanum nigrum L. protoplasts. During later culture stages, most of these “outer-wall plasmodesmata”, which had been exposed to the culture medium, disappeared, except for those near the periphery of division walls between daughter cells and those near non-division walls between secondarily associated unrelated cells. Moreover, in the peripheral parts of older division walls, there were continuous branched plasmodesmata which showed the typical morphological characteristics of secondary cell connections: several cytoplasmic strands joined in the median plane of the cell wall and were often linked by so-called median cavities. Evidence is presented that this type of continuous plasmodesma originates from the fusion of the half-plasmodesmata which persisted in the outer walls adjacent to the division wall. Due to growth of the cells after division, opposite parts of the outer walls of the daughter cells come into close contact and fuse, elongating the original division wall peripherally. Opposite half-plasmodesmata remaining in these parts of the outer wall may thereby also be brought into contact and fuse to form a continuous secondary cell connection in the secondarily coalesced wall part. Our assumption is supported by further experiments: (i) longterm video observations of living cells showed differences in the development of the shapes of regenerating cells and (ii) electron-microscopical investigations showed differences in the frequency of the, presumably secondary, cell connections in the peripheral parts of the division walls — both related to the firmness of the embedding medium. In the central parts of division walls, unbranched primary cell connections were found as well as a second type of continuous branched plasmodesma showing an entirely different branching pattern: the region of the middle lamella was always traversed by straight, unbranched parts of these plasmodesmata and the branches occurred exclusively within the younger wall layers. Evidence is given that these branches are modifications of originally unbranched primary plasmodesmata, developing during subsequent thickening of the division wall.

Trisomy of human chromosome 18: molecular studies on parental origin and cell stage of nondisjunction.

We investigated the parent and cell division of origin of the extra chromosome 18 in 62 aneuploids with a free trisomy 18 by using chromosome-18-specific pericentromeric short-sequence repeats. In 46 cases, DNA of patients was recovered from archival specimens, such as paraffin-embedded tissues and fixed chromosomal spreads. In 56 families, the supernumerary chromosome was maternal in origin; in six families, it was paternal. Among the 56 maternally derived aneuploids, we could exclude a postzygotic mitotic error in 52 cases. Among those in which the nondisjunction was attributable to an error at meiosis, 11 were the result of a meiosis I nondisjunction and 17 were caused by a meiosis II error. This result differs markedly from findings in acrocentric chromosomes where nondisjunction at maternal meiosis I predominates. Among the six paternally derived cases, two originated from a meiotic error, indicating that a nondisjunction in paternal meiosis is not as rare as previously suggested.

Neighborhood Diversity: Social Change, Ambiguity, and Fair Housing Since 1968

: More than a generation after the Civil Rights Act of 1968, fair housing remains an ambiguous and unattained goal in the United States. Entrenched opposition, weakness in the original legislation, racial preferences, and division among proponents help to explain this situation. The author examines the latter two factors and identifies the role of historical change in the persisting weakness of fair housing. Through an analysis of the prointegration movement, he argues that demographic and social change since 1968 have eroded support among both whites and blacks for integration and open housing and exacerbated divisions among proponents of fair housing.

Patterns of bud-site selection in the yeast Saccharomyces cerevisiae.

Cells of the yeast Saccharomyces cerevisiae select bud sites in either of two distinct spatial patterns, known as axial (expressed by a and alpha cells) and bipolar (expressed by a/alpha cells). Fluorescence, time-lapse, and scanning electron microscopy have been used to obtain more precise descriptions of these patterns. From these descriptions, we conclude that in the axial pattern, the new bud forms directly adjacent to the division site in daughter cells and directly adjacent to the immediately preceding division site (bud site) in mother cells, with little influence from earlier sites. Thus, the division site appears to be marked by a spatial signal(s) that specifies the location of the new bud site and is transient in that it only lasts from one budding event to the next. Consistent with this conclusion, starvation and refeeding of axially budding cells results in the formation of new buds at nonaxial sites. In contrast, in bipolar budding cells, both poles are specified persistently as potential bud sites, as shown by the observations that a pole remains competent for budding even after several generations of nonuse and that the poles continue to be used for budding after starvation and refeeding. It appears that the specification of the two poles as potential bud sites occurs before a daughter cell forms its first bud, as a daughter can form this bud near either pole. However, there is a bias towards use of the pole distal to the division site. The strength of this bias varies from strain to strain, is affected by growth conditions, and diminishes in successive cell cycles. The first bud that forms near the distal pole appears to form at the very tip of the cell, whereas the first bud that forms near the pole proximal to the original division site (as marked by the birth scar) is generally somewhat offset from the tip and adjacent to (or overlapping) the birth scar. Subsequent buds can form near either pole and appear almost always to be adjacent either to the birth scar or to a previous bud site. These observations suggest that the distal tip of the cell and each division site carry persistent signals that can direct the selection of a bud site in any subsequent cell cycle.

Endoscopic transaxillary subpectoral breast augmentation.

The transaxillary approach to breast augmentation is an established technique that offers the advantage of a remote incision in an aesthetically acceptable area. The main disadvantage to this approach is the lack of visualization of the implant pocket, necessitating blind, blunt dissection of the pectoral muscle origins. Occasionally, this limitation may result in improper implant placement and poor aesthetic results. In order to address this shortcoming, we have explored the use of minimally invasive endoscopic techniques in transaxillary augmentation to allow division of the pectoral muscle origin under direct visualization, effectively lowering the inframammary crease. Initial dissections and instrument development were performed in five unpreserved female cadavers. Subsequently, 103 implants have been placed in 53 patients utilizing the endoscopic transaxillary approach. Follow-up ranges from 2 weeks to 20 months. There have been no hematomas, infections, capsular contractures, or other complications. Aesthetic results have been good, and patient acceptance is high. By providing predictable and reproducible control of the inframammary crease, endoscopic dissection has allowed us to expand our indications for the transaxillary approach to breast augmentation. Surgical technique and brief clinical experience are described.

New PPM-CDMA hybrid for indoor diffuse infrared channels

An original hybrid pulse position modulation code division multiple access (PPM-CDMA) communication technique that uses optical orthogonal codes (OOCs) is proposed and studied in the context of the indoor infrared channel. At the optimum PPM order and over the range of parameters considered, the hybrid is shown to achieve more than five times the bit rate achievable using conventional on off keying (OOK) CDMA under bandwidth constraints. Original results are presented for the false alarm errors due to the OOC crosscorrelations, and the optimum system operating parameters that minimise these errors are specified.

The origin of 47,XXY and 47,XXX aneuploidy: heterogeneous mechanisms and role of aberrant recombination.

We investigated the parent and cell division of origin of the additional sex chromosome in 142 males with a 47,XXY constitution and 50 females with a 47,XXX constitution. In 66 of the 47,XXY males the additional chromosome was paternal in origin and in 76 it was maternal in origin, while among the 47,XXX females only 5 had an additional paternal X chromosome, the remaining 45 having an additional maternal chromosome. Among the 107 maternally derived aneuploids for whom it was possible to determine the cell division of origin, 73 were the result of a mat MI error, 24 the result of a mat MII error and 10 the result of a post zygotic mitotic (PZM) error involving the maternal X chromosome. Among those in which the non-disjunction was attributable to an error at the first meiotic division (MI) we observed three different mechanisms of origin. Approximately 30% were associated with complete absence of recombination (nullichiasmate); approximately 24% were associated with a normal number of recombinant events but an abnormal distribution of exchanges (perturbed recombination), while approximately 45% were associated with a normal number and distribution of recombinant events (normochiasmate). Nondisjunction due to an error at the second meiotic division (MII) was associated with a slight reduction in the total number of recombinant events and an abnormal distribution of exchanges. Thus of the four different meiotic mechanisms of origin, three were associated with an abnormal number and/or distribution of exchange events. There was no evidence of an increased paternal age in the aneuploids of paternal origin.(ABSTRACT TRUNCATED AT 250 WORDS)

The Determination of Spindle Polarity in Early Mitotic Stages of the Dividing Grasshopper Neuroblasts: (unequal cytokinesis/neuroblast/spindle axis/electron dense layer/microdissection).

Although the spindle body of the grasshopper neuroblasts at the early mitotic stages does not have any mechanical linkage to the surrounding cell cortex, a spindle axis is inevitably oriented in parallel with the original division axis. The present study analyzes how the definite orientation of spindle axis along the cap cell (CC)-ganglion cell (GC) axis of the neuroblast is maintained during these stages by use of the microdissection technique and electron microscopy. After removing a microneedle from the cell, metaphase spindles approximately 90°. rotated were able to return autonomously to the original axis. After the middle anaphase, however, the rotated spindle could not return at all. The electron microscopic observations revealed a characteristic behavior of an electron dense layer (EDL) in the CC-side cortex during neuroblast mitosis. The EDL first appeared at very late prophase and became most conspicuous at metaphase. It became discontinuous by the beginning of middle anaphase and then completely disappeared at middle anaphase. So long as an EDL existed in the CC-side polar cortex, 90° rotated spindle bodies were able to return autonomously to the original axis. After the disappearance of the EDL, the autonomous return of the rotated spindle no longer occurred. From these circumstantial evidence, it is conceivable that the orientation of the spindle body along the CC-GC axis is maintained by the interaction between the EDL and the spindle pole.

Functional division and reconstruction of a plasmid replication origin: molecular dissection of the oriV of the broad-host-range plasmid RSF1010.

Two single-stranded DNA initiation signals (designated ssi) present in the origin of vegetative DNA replication (oriV) of the broad-host-range plasmid RSF1010 are essential for the priming of replication of each complementary DNA strand of this plasmid in Escherichia coli. Each of the RSF1010 ssi signals, ssiA and ssiB, could be replaced by a primosome assembly site from plasmid pACY184 or from bacteriophage phi X174. In these chimeric origins, replication of the strand complementary to that containing the primosome assembly site was no longer dependent on the RSF1010 primase, protein RepB', but required the E. coli primase, DnaG. If both ssiA and ssiB sites of RSF1010 were replaced by primosome assembly sites, protein RepB' was no longer essential for the replication at this origin, whereas proteins RepA and RepC of RSF1010 were still required. These results strongly suggest that the two ssi sites and the RepB' protein actually direct the priming of DNA synthesis in the replication of RSF1010, and the proteins RepA and RepC are involved in the prepriming events--i.e., the opening of the DNA duplex at oriV. It is evident that the origin of RSF1010 can be separated into three functional domains and reconstructed by replacing the ssi sites with heterologous elements.

Microdissection Studies on the Polarity of Unequal Division in Grasshopper Neuroblasts: II. Cell Division in Binucleate Neuroblasts: (unequal division/grasshopper neuroblasts/binucleate cells).

The grasshopper neuroblast divides unequally to produce two types of cells: a large daughter neuroblast that contains a doughnut-shaped nucleus and repeats unequal division with definite polarity, and a small daughter ganglion cell that has a spherical nucleus with low mitotic activity. Binucleate neuroblasts were induced by preventing cytokinesis in the course of microdissection experiments, and subsequent divisions were traced to analyze the factors that determine the polarity of unequal division. In binucleate neuroblasts, both daughter chromosome groups developed into neuroblast-type nuclei. Mitosis of the two nuclei proceeded synchronously. Although the axes of the two mitotic apparatuses formed at late prophase were random in direction, they became parallel with the original division axis at metaphase. The two mitotic apparatuses shifted simultaneously toward the ganglion cell side during anaphase, just as in normal neuroblasts, and the binucleate cell divided unequally. These findings showed that the poearity of unequal division is strictly maintained in grasshpper neuroblasts, even when they contain two nuclei.

Equipment

Instantaneous measurement of ultraviolet radiation intensity during accelerated weather and light‐fastness testing is now said to be possible with the introduction by Heraeus (Original Hanau division) of a new UV meter.

From Exegesis to Hermeneutics: The Problem of the Contemporary Meaning of Scripture

AbstractPart I discusses the recent history of Roman Catholic biblical scholarship which has led to the emergence of the problem of how the results of scientific biblical research can and should be integrated into the pastoral project of the Church. It suggests that the original division of labor among biblical scholars, theologians, and pastors is no longer visible (if, indeed, it ever was).Part II describes three models of biblical research in terms of the conception of Scripture and the theory of interpretation operative in each. The three models are not proposed as equally adequate. Proof-texting, the model which was paradigmatic prior to Divino Afflante Spiritu (1943), is presented as seriously defective. Historical critical exegesis, the model which has been, and to a large extent remains, paradigmatic is shown to be considerably more adequate. However, a variety of forces is placing pressure on this model, revealing its inadequacies when it terminates in historical reconstruction. The third model, the hermeneutical, seems capable of integrating exegesis into a process of interpretation which will prove more adequate to the task of revealing both what the text meant in its own time and culture and what the text means today.Part III draws out the implications of each of the three models for the relationship between biblical research and pastoral practice.

Radial Growth in the Cycadales

The development of radial growth which leads to the pachycaulous form was investigated in eight of the 10 genera of the Cycadales; i.e., Ceratozamia, Cycas, Dioon, Encephalartos, Macrozamia, Microcycas, Stangeria, and Zamia. In all taxa, development of radial growth is essentially the same: a primary thickening meristem is differentiated in the stelar region of the cotyledonary node of the seedling at germination and produces derivatives mainly centrifugally. This primary thickening meristem (PTM) then differentiates acropetally and becomes continuous with the peripheral zone of the shoot apex. At first the PTM is a vertical cylinder, but as the seedling continues to grow into an adult plant, the PTM shows a more horizontal orientation (like an open umbrella) and produces the broad cortex. Secondary growth is by a vascular cambium which produces secondary xylem to the inside and secondary phloem to the outside. The broad pith originates from derivatives of the rib meristem of the massive shoot apex. The seedling and young plant is composed of a shortened shoot (i.e., no internodes) produced by the PTM and rib meristem, and a large fleshy primary root which results from a diffuse growth pattern. Individual cells in both the pith and cortex of the root divide. Their derivatives divide at right angles to the original division plane. Thus, quartets and even octets of cells are recognizable and can be traced to individual parent cells.

RADIAL GROWTH IN THE CYCADALES

The development of radial growth which leads to the pachycaulous form was investigated in eight of the 10 genera of the Cycadales; i.e., Ceratozamia, Cycas, Dioon, Encephalartos, Macrozamia, Microcycas, Stangeria, and Zamia. In all taxa, development of radial growth is essentially the same: a primary thickening meristem is differentiated in the stelar region of the cotyledonary node of the seedling at germination and produces derivatives mainly centrifugally. This primary thickening meristem (PTM) then differentiates acropetally and becomes continuous with the peripheral zone of the shoot apex. At first the PTM is a vertical cylinder, but as the seedling continues to grow into an adult plant, the PTM shows a more horizontal orientation (like an open umbrella) and produces the broad cortex. Secondary growth is by a vascular cambium which produces secondary xylem to the inside and secondary phloem to the outside. The broad pith originates from derivatives of the rib meristem of the massive shoot apex. The seedling and young plant is composed of a shortened shoot (i.e., no internodes) produced by the PTM and rib meristem, and a large fleshy primary root which results from a diffuse growth pattern. Individual cells in both the pith and cortex of the root divide. Their derivatives divide at right angles to the original division plane. Thus, quartets and even octets of cells are recognizable and can be traced to individual parent cells.