bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the ejection properties of asters: astral microtubule turnover influences the oscillatory behavior and positioning of mono-oriented chromosomes
Authors: Ault Jeffrey G. , Demarco Anthony J. , Salmon Edward D. , Rieder Conly L. 
Published: April 2021

ABSTRACT
The position of a mono-oriented chromosome changes as it oscillates to and from the pole to which it is attached. Such oscillatory behavior reveals that the net force on a mono-oriented chromosome is constantly changing. Fluctuations may occur in both the polewardly directed force acting at the kinetochore and the opposing outwardly directed force associated with the aster. We have examined the ejection properties of the aster –as well as the oscillatory behavior and positioning of monooriented chromosomes –in relation to astral microtubule turnover. We treated cells containing monopolar spindles with drugs that affect microtubule turnover, either by promoting the depletion of dynamically unstable astral microtubules (nocodazole and colcemid) or by augmenting their numbers and stability (taxol). Both types of drugs stopped the oscillatory behavior of mono-oriented chromosomes within seconds. The final position of the chromosomes depended on how microtubule turnover was affected. In the case of nocodazole and colcemid, non-kinetochore astral microtubules were depleted first and the kinetochore-to-pole distance shortened. In these cells chromosome fragments generated bylaser microsurgery were no longer expelled from the center of the aster. By contrast, with taxol the number of non-kinetochore microtubules increased and the astral ejection force became stronger as shown by the finding that the chromosomes moved away from the pole to the periphery of the monaster. Moreover, arms severed from chromosomes at the periphery of the taxol monaster failed to move further away from the aster’s center. From these observations we conclude that the oscillatory movements and changing position of a mono-oriented chromosome relative to the pole are mediated by changes in the number of astral microtubules. The dynamic instability of astral microtubules that leads to a rapid turnover may contribute to the astral ejection force by allowing the continual growth of microtubules out from the aster. Growing astral microtubules may exert a pushing force that their rigidity maintains until their depolymerization.
The role of the flagellar transition region: inferences from the analysis of a Chlamydomonas mutant with defective transition region structures
Authors: Jarvik Jonathan W. , Suhan Joseph P. 
Published: April 2021

ABSTRACT
Thin-section electron microscopy of the Chlamydomonas reinhardtii mutant vfl-2 revealed striking defects in the transition region between basal body and flagellum. In place of the highly organized transition cylinders and stellate fibers characteristic of wild type, variable quantities of poorly organized electron-dense material were present. In many cases the transition region was penetrated by central pair microtubules that passed from the axoneme into the basal body. On the basis of these observations we propose that an important function of the structures present in the normal transition region is to physically exclude the central pair microtubules from the basal body.
The transition region is the site of flagellarautotomy –the process by which doublet microtubules are severed and flagella are released from the cell. It has been claimed that autotomy is caused by contraction of the centrin-containing stellate fibers, resulting in the mechanical severing of the doublet microtubules and a concomitant reduction of the diameter of the axoneme adjacent to the abscission point. Our observations do not support this claim in that vfl-2 cells, which lack organized stellate fibers, display effective autotomy unaccompanied by detectable narrowing of the axoneme.
Binding of latent and high M
r active forms of stromelysin to collagen is mediated by the C-terminal domain
Authors: Allan J. A. , Hembry R. M. , Angal S. , Reynolds J. J. , Murphy G. 
Published: April 2021

ABSTRACT
A specific high-titre polyclonal antiserum to recombinant human prostromelysin was raised in a sheep and shown by immunoblotting to detect latent prostromelysin, high and low Mr active forms and the C-terminal domain. This antiserum was used to demonstrate by indirect immunofluorescence that latent and active high Mr prostromelysin bind to reconstituted collagen fibrils, and to other extracellular matrix components in tissues ex vivo but that active low Mr stromelysin does not Isolation of the C-terminal domain was carried out to demonstrate that stromelysin binding was through this domain.
By use of an antiserum to the tissue inhibitor of metalloproteinases (TIMP) it was shown that TIMP is unable to bind to reconstituted collagen fibrils. TIMP, however, will bind when active high Mr stromelysin is present but not if latent prostromelysin is bound.
We conclude that stromelysin has different binding specificities from those previously documented for collagenase; only active collagenase binds to reconstituted collagen fibrils. However, TIMP binds to the active forms of both stromelysin and collagenase when these are bound to the collagen fibrils. These results have important implications for the interpretation of immunolocalization data in establishing the roles of metalloproteinases and their inhibitors in vivo.
Structural analysis and expression of human desmoglein: a cadherin-like component of the desmosome
Authors: Nilles Laura A. , Parry David A. D. , Powers Eric E. , Angst Brigitt D. , Wagner Rita M. , Green Kathleen J. 
Published: April 2021

ABSTRACT
Desmosomes are adhesive cell junctions found in great abondance in tissues that experience mechanical stress. The transmembrane desmosomal glycoproteine have been proposed to play a role in cell adhesion; desmoglein I (DGI) is a major member of this class of desmosomal molecules. However, evidence supporting a role for DGI in cell adhesion or in the plaque is lacking. In order to begin to understand DGI function we have identified human cDNA clones encoding the entire mature polypeptide of 1000 amino acids. Our data suggest that like the bovine DGI molecule human DGI is highly related to the calcium-dependent class of cell adhesion molecules known as cadherins. Four related extracellular domains located in the amino-terminal domain of the molecule contain putative calcium binding sites originally identified in the cadherins. The highest degree of similarity between human N-cadherin and human DGI, and likewise between bovine DGI and human DGI, is greatest in the most amino-terminal extracellular domain. This suggests a conserved functional role for the extracellular domains, perhaps in calcium-mediated cell adhesion. The cyto-plasmic portion of the molecule contains a cadherinlike region and, like bovine DGI, a carboxy-terminal tail that is not present in the cadherins, comprising three additional domains. One of these contains a novel repeating motif of 29±1 residues, first identified in bovine DGI. Each of the highly homologous repeating units is likely to consist of two β-strands and two tums with special characteristics. Five amino acids that are identical in bovine and human DGI lie in the second of the two predicted β-strands, and intriguingly contain putative target sites for protein kinase C. On the basis of structural analysis, a model predicting the disposition of human DGI domains in the desmosome is proposed.
Northern analysis suggests that unlike bovine epidermis, which expresses a single mRNA of reported size ∼7.6kb, human foreskin and cultured keratinocytes display a complex pattern with bands of —7.2, 4.0 and 3.0 kb. Each of these cross-hybridizing mRNAs is coordinately expressed in normal human keratinocytes in response to long-term culture and increased calcium.
Notes on the structure of oscillatortæ, with a description of a new species, possessing a most remarkable locomotive power, not cilia
Authors: D’Alquen F. 
Published: April 2021

ABSTRACT
The study of the structure of the Oscillatoriœ is particularly interesting, from the fact that we may not unreasonably expect to find in it a key to the singular motion from which they have received their generic name, and which now, for more than a century,* has formed an object of curiosity and interest to the microscopist without having received as yet a satisfactory explanation. In one species at least, I think, I have been able to make out the leading features of its structure and the mechanism of its locomotion. The description of this, to me, new species I wish to preface by a few observations, containing some new facts regarding the structure of Oscillatoria in general, which may, perhaps, interest some of your readers ; in doing so, it will, however, not be necessary to refer to the general character of these interesting organisms, as they must be familiarly known to every one who is in the habit of using the microscope, and therefore I plunge at once in medias res.
On the ossification of the primordial cartilage
Authors: Baur A. 
Published: April 2021

ABSTRACT
A Microscopical analysis of the changes which take place in the ossification of cartilage has two questions to resolve: First, in what way does the peculiar structure of osseous substance arise from the so widely different structure of cartilage ? and, secondly, in this process, in what relation do the elements of the cartilage stand towards those of the bone? The latter question especially, since it has become known that bone may be formed without any pre-existing cartilage, has acquired redoubled interest.
A monograph of the fresh-water polyzoa
Authors: Allman Geo. J. 
Published: April 2021

ABSTRACT
To the well-known and invaluable series of Monographs by Alder and Hancock, Forbes, Baird, and Darwin, published under the auspices of the Ray Society, we have to announce the addition of the long-expected work of Professor Allman, on the ‘Fresh-water Polyzoa, including all the known species, both British and Foreign.’
Catalogue of Desmidiacece
Authors: Ball R. , Archer Wm. 
Published: April 2021

ABSTRACT
The following list of the Desmidiaceæ which I have found about the “Feather-bed” and “Seechon” mountains, near Dublin, is not, of course assumed to be a complete list. It is, however, a perfect one (with, perhaps, the exception of the genus Pediastrum) of the species I have met with in my limited experience; and I have no doubt but subsequent search will very much extend it. I have ventured to append to each species an opinion as to its frequency or rarity, which, I need hardly state, is to be interpreted as the result of my own experience only in a limited district. Some of those I have marked as rare may ultimately prove frequent. I am inclined to corroborate an observation made in Mr. Ralfs’ beautiful f Monograph,’ as to the non-occurrence of the same species in the same pools from year to year. For instance, in the year 1855, a certain pool produced Didymoprium Borreri in great abundance. During 1856 I could not find a single specimen of that species; but its place was taken by a considerably less abundant development’ of Hyalotheca mucosa.
Note on the Distribution of Nerves to the Vessels of the Connective Tissue in the Hilus of the Pio’s Kidney, and on the Ganglia Found in Connection With These Nerves
Authors: Tyson James 
Published: April 2021

ABSTRACT
Premising that these observations are incomplete, though, I believe, accurate as far as they go, my excuse for bringing them under the notice of the Section at this stage is, that its members may have the opportunity of examining the preparations before they become altered. Having been mounted quite two months, they are still in good keeping, though it is impossible to state how long they will remain thus. The observations, when complete, will also have for their object to determine whether these nerves and ganglia are also distributed to the vessels and tubules in the secreting structure of the kidney, as the labours of Beale appear to have shown; failure to demonstrate this latter point being attributed to want of success in the injecting process—a matter of no inconsiderable difficulty, as the entire organ (that of the young pig) was but an inch in length, and the artery, therefore, exceedingly small. It is hoped that further attempts will accomplish this, though Dr. Beale himself, of whose observations these are a repetition, makes no allusion to having found the nerves Upon the tubules and vessels of the pig’s kidney, but has demonstrated them most satisfactorily in this portion of the kidney of the frog and newt, as will be learned later.
On Microscopic Illumination
Authors: Higgins John F. 
Published: April 2021

ABSTRACT
The subject of illumination in the use of the microscope is one upon which much has been written, especially in connection with the merits of various accessories, and yet one the understanding of which is far from general, and, moreover, in reference to which microscopists of acknowledged ability and attainments hold most opposite opinions. In endeavouring to ascertain what are really the facts in the case, and by what rule or rules we should be guided, it becomes necessary, laying aside all previous bias or hitherto conceived opinions, to commence de novo with first principles, and guided by known and absolute laws of light and vision, in conjunction with a careful, complete, and unwearied series of experiments, work out the much desired end.
The Cell Doctrine; its History and Present State
Authors: Tyson James 
Published: April 2021

ABSTRACT
Whilst America is perhaps not doing her share of the work of original observation in the various branches of natural science, we have from time to time abundant proof that her scientific teachers are keeping abreast of the knowledge of the day. Dr. Tyson, who lectures on the microscope and physiology in Philadelphia, has produced in this book an admirable résumé of the history of the various theories and observations on the ultimate structure of organic beings. Whilst giving credit to the earlier observers with the microscope, for their views and observations, he rightly speaks of the researches of Schleiden and Schwann as having introduced a new era into the history of our knowledge of animal and vegetable structure. He passes successively in review the observations of Henle, von Mohl, von Baer, Beale, Bennett, and the views of Huxley. Without going into elaborate detail, he presents the subject in such a way that the student can-not fail to understand the exact bearing of the views of each particular writer, on the subject of what is called “cell-doctrine,” or the “cell-theory.” The author sums up his own views in the following passage.
Notes on Diatomaceæ
Authors: Edwards Arthur Mead 
Published: April 2021

ABSTRACT
I AM one of those who have always strongly advocated the keeping of written and drawn notes by observers of nature. However crude and imperfect the drawings may be, however incomplete the written descriptions, yet, if made conscientiously and with due regard to facts, stating what the observer thinks he sees, they always possess the value of truth, and at the same time serve to place upon record and impress upon the mind many things that would otherwise pass unheeded, and those often of great value. So by following Out such a plan, the mind of the student is drilled in System, the great secret of success in all scientific observations, as well as in other matters. For a long time I have kept a book in which, from day to day, and immediately as observations are made, memoranda are jotted down, often accompanied by sketches, coloured or not, as the subject requires. And on looking back, I frequently find in my older notes the key to some puzzling phenomenon undergoing investigation at a later time. Let not the observer plead the excuse that he cannot draw; I believe that everybody can learn to draw sufficiently well to give a truthful, if not artistic representation of what appears before his eyes. Every one can write well enough to say what he sees when required, and drawing is but a short-hand system of writing.
Notes on Amphidotus cordatos (penn)
Authors: Robertson David 
Published: April 2021

ABSTRACT
In the early part of 1868, on the shores at Cumbrae, my attention was attracted to many holes occurring in the sand. In tracing them to a depth of four or five inches, I found an Amphidotus cordatus under each hole. The diameter of the hole was about equal to that of a crowquill, and often irregular, and rose straight over the long spines surrounding the dorsal impression of the test. By placing one of the animals in a glass jar with two or three inches of sand below and over it, and covering the whole with water, an opportunity was afforded of seeing how the holes were produced and kept open. Long contractile processes, with tentaculated heads— described by Forbes as “long ringed worm-like suckers,” and by John Johannes Müller as “locomotive feet”—were thrust up through the sand, and were seen slowly, and apparently searchingly, wandering over its surface, then grasping particles of the sandy matter in their tentacles, and finally dragging them rapidly down into the hole. As these holes extend from four to five inches into the sand, and I have seen these prehensile tentacles stretch between two and three inches over its surface, the length of these instruments cannot be less than six or seven inches.
On some Freshwater Rhizopoda, New or Little-Known. Fasciculus II. On Amphizonella Vestita (Sp. Nov.), Acanthocystis Spinifera (Greeff) and Plagiophrys Sphærica (Clap, et Lachm)1
Authors: Archer William 
Published: April 2021

ABSTRACT
On a former occasion,2 I brought before the notice of those interested in types of existence so lowly, a series of forms in certain groups of Rhizopoda, at once novel to our freshwaters, as well as some of them possessing in themselves a considerable interest as connecting links, leading on to their more complex and structurally more differentiated marine relatives. Having, since then, continued to bestow some attention to the subject, I venture to propose to bring forward from time to time, as opportunity may offer, such casual jottings, or accounts of any few additional new forms, as good fortune may enable me.
On the Structure and Origin of the Spermatophors, or Sperm-Ropes, of two Species of Tubifex
Authors: Lankester E. Ray 
Published: April 2021

ABSTRACT
In the April number of this Journal last year I called attention to the fact that the so-called opalinoid parasite Pachydermon of M. Claparède,found in the copulatory pouches of certain Oligochœtous Annelids, is in reality a felted mass of spermatozoa, i.e. a spermatophor.
On the Colour of Leaves at Different Seasons of the Year
Authors: Sorby H. C. 
Published: April 2021

ABSTRACT
The number of distinct vegetable colouring matters is so great, and there are so many plants which merit careful examination, that any general conclusions I might now form would probably be considerably modified by further inquiry. This makes me hesitate in giving a decided opinion on many questions connected with my subject; but, at the same time, 1 feel that it is better to run the risk of making some errors than to describe the facts without uniting them by such an amount of theory as may serve to lead to intelligible general principles. I shall, therefore, endeavour to draw such conclusions as the present state of the subject admits, and beg my readers to place no more value on them than I do myself, and to look upon them as provisional, to be modified as our knowledge increases.
Some Remarks on the Nerves of the Cornea of the Rabbit and Frog
Authors: Moseley H. N. 
Published: April 2021

ABSTRACT
Gold preparations of the cornea after they have been in the cabinet for five or six months in a glycerine mount, generally turn dark and very often lose their transparency so thoroughly as to become apparently spoiled. It will be found, however, that from such specimens really beautiful preparations can often be obtained. After this long maceration in glycerine, the cornea can readily be torn into a series of extremely fine layers, so fine, indeed, as in the case of the frog, to be only one cornea-corpuscle thick. As the nerves continually get darker and darker by the further reduction of the gold chloride, these thin layers are extremely instructive with regard to these nerves generally, and especially with regard to their relation to the corpuscles, which it is extremely difficult if not impossible to determine when several layers of corpuscles with the surrounding nerves are in the field at once. Although so much has been written on the subject of the nerves of the cornea, it is hoped that the following remarks and accompanying drawings may not be without interest.
Recent Researches in the DiatomaceÆ.
Authors: O’meara Eugene 
Published: April 2021

ABSTRACT
The second of a series of treatises in course of publication under the direction of Dr. Johannes Hanstein, under the title of ‘Botanische Abhandlungen aus dem Gebiet der Morphologie und Physiologie,’ is eminently calculated to interest such as are engaged in the study of the Diatoms, and promote their knowledge of these interesting and ornamental organisms. These benefits, however, must be confined to those students who are acquainted with German, unless some one undertake to remove the obstruction, and present the treatise in an English dress. ‘
A Résumé of Recent Views respecting the Nature of Lichens
Authors: Archer W. 
Published: April 2021

ABSTRACT
A Novel hypothesis respecting the nature of Lichens, which was first propounded by Prof. Schwendener of Basel, and has since to a greater or less extent been adopted by other experienced observers, has for some time past been a subject of controversy between them and botanists of the older school. The “gonidia question,” as it is called, has been discussed in several of the continental journals, and a résumé of some of the papers on both sides will probably possess some interest for English readers. Briefly Schwendener’s view is that the growths which we know as “Lichens” are not independent plants, but ascomycetous fungi, to which certain unicellular or filamentous algæ serve as host-plants, and, therefore, that these latter have hitherto been erroneously regarded, under the name of “gonidia,” as special organs of “Lichens.” Hence each representative of the class is a compound organism made up of two primarily distinct elements.
Review: The Anatomy of the Lymphatic System
Authors: Klein E. 
Published: April 2021

ABSTRACT
This valuable memoir is doubtless one of the most important contributions made to histology within the past year. We are, however, relieved from the necessity of giving a very elaborate notice of the contents, since a portion of the work has already appeared in our journal (‘Quar. Jour. Micro. Sci.,’ 1872, p. 142). ‘