bluuebunny/crossref_metadata_2025_split huggingface dataset:
BIOLOGICAL EFFECTS OF U.V. IRRADIATION IN CHAOS CHAOS*
Authors: Montgomery P. O'B. , Bonner W. A. , Hundley L. L. , Ashworth C. T. 
Published: November 2011

SYNOPSISContinuous ultraviolet irradiation of the amœgba, Chaos chaos, was accomplished by ultraviolet flying‐spot television microscopy, and the results were recorded by time‐lapse motion‐picture photography.A study of such motion‐picture films reveals that Chaos chaos progressively reacts to ultraviolet irradiation administered in this way by:(a) increased serration of the plasmalemma(b) increased gelation of the cytoplasm(c) decreased and spasmodic motion of the entire amœba(d) formation of plasmalemma blebs(e) portions of plasmalemma and endoplasm being pinched off into the surrounding medium, (f) sudden spasmodic contractile dissolution of the amœba into the medium.Electron micrographs of intact irradiated amœba show the major change to be one of increased accumulation of water in the cytoplasm, without apparent alteration of plasmalemma, mitochondria, or nuclear membrane.
A METHOD FOR THE ROUTINE EVALUATION OF DRY MASS FROM ELECTRON MICROGRAPHS
Authors: Silvester N. R. , Burge R. E. 
Published: November 2011

SYNOPSISUnder certain conditions the optical transmission of the negative of an electron micrograph is linearly related to the mass per unit area of the corresponding specimen. A polarizing microscope was modified so that the rotation of a polaroid in the system, which restored a photo‐multiplier current to a fixed value, was a measure of the transmission of a selected area of a micrograph placed on the stage. This null‐point method can be used in the routine evaluation of the dry mass of isolated specimens from their electron micrographs. The theory of the method is given and measurements on standard objects are described that demonstrate its validity of application. Optimum conditions for measurement are considered and experimental errors are discussed. The errors in the present measurements were estimated to be less than 6 p.c. The null‐point method was rapid and simple in operation and should be useful in statistical determinations of the mass of non‐homogeneous specimens.
A NEW HELIOSTAT FOR DARK‐GROUND MICROSCOPY
Authors: Pijper Adrianus 
Published: November 2011

SYNOPSISSunlight dark ground microscopy with a simple heliostat has revealed a straight tail as the origin of the flagella of most motile bacteria. This tail changes into helices (“flagella”). These show specific wavelengths, with “biplicity” and take part in agglutination. All this has also been recorded cinemicrographically on 16 mm film. Among other subjects studied and filmed with this sunlight technique were bacterial motility, other types of bacterial flagella, including those of Spirilla and Vibrios, and the effect of bacteriophage and penicillin on certain bacteria.A description is here given of a new more elaborate heliostat which will throw a brighter and steadier beam of sunlight into the microscope, thus improving and facilitating further observations of which preliminary results are given here.
APPARATUS FOR THE STUDY OF LIVING HUMAN CELLS
Authors: Dawson Mary 
Published: November 2011

SYNOPSISAn assembly of equipment for the study of living human cells is described. It is designed to keep the cells under study living, sterile, adequately nourished, at their optimum temperature and observable throughout an experiment, and to subject them to as little light as possible. The apparatus consists of a phase‐contrast microscope, a cine camera, a micro‐flash unit, a time‐lapse unit, and a warmed perfusion chamber. The microscope, camera, and flash unit are standard, commercially available items. The time‐lapse unit, its ancillary equipment, and the perfusion chamber are of the author's design.
THEORY OF ELECTRON AUTORADIOGRAPHY
Authors: Pelc S. R. 
Published: November 2011

So far autoradiography has mainly been used at the level of light microscopy and the theory of autoradiography was developed for this type of work. Whatever the intended application, the problems involved can be grouped under (a) resolving power, (b) sensitivity, and (c) technique.An autoradiograph is prepared by bringing a specimen containing some radioactive material in contact with a photographic emulsion and storing the preparation in the dark for exposure. During the time of exposure some of the radioactive material will decay and the ionizing radiations emitted will produce latent images in the emulsion. After photographic processing the developed image will appear as an accumulation of silver grains which are seen as round black spots under the light microscope and as filamentous structures in the electron microscope.
SOME EXPERIMENTS CONCERNING THE LIMITATIONS AND ERRORS IN SIZE MEASUREMENT OF SMALL OBJECTS BY VISUAL MICROSCOPY
Authors: Charman W. N. 
Published: November 2011

SYNOPSISThe systematic errors which arise in the measurement of small, non‐periodic objects by visual microscopy are discussed, together with a method for reducing these errors by calibration with objects of known size. Such a calibration is described for the case where the diameters of circular holes and opaque disks are measured using a filar micrometer eyepiece, an oil‐immersion objective, and full‐cone illumination. Examples are given showing the influence of the numerical apertures of the condenser and objective upon the sizing errors. The results are used to derive size correction factors applicable to the measurement of any thin, high contrast object when the same sizing technique is used. Values are also given for the useful lower limits of measurement. Further experimental evidence emphasizes the difficulty of accurate measurement where the objects are of finite thickness.
LYMPH NODE STRUCTURE IN DICEROS BICORNIS
Authors: Cave A. J. E. , Aumonier F. J. 
Published: November 2011

SYNOPSISThe lymph nodes of a second young specimen of the African Black Rhinoceros (Diceros bicornis) prove to be, like those of an earlier specimen, hæmolymph nodes. An unusual (and doubtless pathological) feature thereof is a metamorphosis of the endothelial lining of the precapillary arteries within all nodes examined. Histological evidence suggests that the ordinary lymph node may assume hæmolymph characters under appropriate physiological stimulus.
ON THE STRUCTURE OF THE RETINA OF MAN AND MONKEY
Authors: Leach E. H. 
Published: November 2011

SYNOPSISAfter formaldehyde fixation, three types of cone can be described in the retina of man and monkey. The differences are due to a fixation artifact but represent an inherent non‐identity, which is imperceptible after better fixation. There is no evidence to suggest that those three types perform different functions in colour vision and it is more likely that they represent different stages of activity or degeneration.The outer segment of the cones is composed of a uniform core surrounded by a cell membrane, which is discontinuously thickened to form a thread disposed as a series of rings or a spiral, which is myelin in nature and has a high refractive index. Some of the rods show a similar structure of the outer segment, particularly in man and the baboon. Although unpigmented, the thread appears opaque when sections are examined in a mountant of low refractive index.
EXPERIMENTAL MEASUREMENTS OF DIFFRACTION IMAGES IN AXIAL INCIDENT ILLUMINATION
Authors: Charman W. N. 
Published: November 2011

SYNOPSISThis paper discusses the relationship between the diffraction images formed by reflecting objects under axial incident illumination and those of transparent objects in axial transmitted illumination. Experiments to measure the diffraction images produced by the incident illumination of circular absorbing holes in an opaque reflecting film of aluminium are described; the results are compared with those reported earlier for the images of opaque disks of the same diameter illuminated by transmitted light. The differences between the two types of images are discussed, together with their effect on visual measurements.
THE ULTRASTRUCTURAL LOCALIZATION OF PHOSPHATASES IN THE NEURONES OF THE SNAIL, HELIX ASPERSA
Authors: Meek G. A. , Lane Nancy J. 
Published: November 2011

SYNOPSISThe lipid droplets and other cell organelles in the cytoplasm of the neurones of the common snail, Helix aspersa, have been studied with the electron microscope: (1) after fixation in the conventional osmium tetroxide media, without incubation; (2) after incubation for the localization of thiamine pyrophosphatase (TPP‐ase) and inosinc diphosphatase (IDP‐ase) by Novikoff and Goldfischer's method (1961); and (3) after incubation for acid phosphatase according to the technique of Holt and Hicks (1961a, b). The three types of lipid droplet described by Chou and Meek (1958) are readily identifiable after all the procedures used, and so is the lamellar Golgi apparatus. It is therefore concluded that the ultrastructure of the Golgi apparatus cannot be an artifact of fixation. TPP‐ase and IDP‐ase activity are found in the lamellæ of the Golgi apparatus and in the phospholipid droplets; less activity is found in the mixed lipid droplets and none in the triglyceride droplets. This evidence indicates that there are certain similarities between the lamellæ of the Golgi complex and the membranes of the phospholipid droplets. High levels of acid phosphatase activity are present in the mixed lipid droplets; these may therefore be the morphological counterparts in Helix neurones of the “lysosomes” defined biochemically by de Duve (1959). Some acid phosphatase activity is also found in the phospholipid droplets, and in the lamellæ and vesicles of the Golgi apparatus. The mixed lipid droplets appear to contain triglyceride inclusions, and it is suggested that their phospholipid content may be concerned with the metabolism or the transfer of neutral lipids in the cell.
The size of bacteria, as measured by interference microscopy
Authors: ROSS K. F. A. , GALAVAZI G. 
Published: November 2011

SYNOPSISBacteria were examined with a Smith interference microscope using a half‐shade eyepiece and photomicrographs of their images were prepared. Microdensitometer traces on the negatives demonstrated conclusively that the method developed by Ross in 1957 to measure the thickness of bacteria was subject to systematic error. This error was eliminated by modifying the half‐shade eyepiece so that its comparison area was no larger than the image of a single bacterium; a critical comparison of this new method of measurement of phase change through small microscopic objects demonstrated its advantages over the other well‐established methods.Measurements of bacterial thickness obtained by this new method are markedly lower than those obtained by other interferometric methods; they are, however, still slightly higher (by a maximum of 30 p.c.) than the values obtained by measuring the widths of similar bacteria directly from the mid‐points of the diffraction fringes visible at the boundaries of the image. The work of Wolter and of Charman is discussed in the light of these findings.
Silver iodate techniques for the histological demonstration of normal and pathological nervous tissue
Authors: DUCKETT SERGE , TRIGGS MARGARET 
Published: November 2011

SYNOPSISMethods are described for staining cells of the nervous system using sodium and potassium iodate instead of the carbonate salts as used in the classical Hortega techniques. The methods are quick and easy, the rate of success high, and tissues which have been fixed for a long time in formol can be used.
Stereologic techniques in microscopy
Authors: FREERE R. H. , WEIBEL E. R. 
Published: November 2011

SYNOPSISThe principal measuring methods employed in morphometry, generally known as stereology, allow information on volumes, surface areas, numbers of structures, and many other dimensions to be derived from simple counting operations. Until relatively recently these techniques have found only limited application in biology, although they have been used for many years in the inorganic sciences. With the development of reliable quantitative methods in physiology and biochemistry, however, stereologic techniques are becoming increasingly important and a number of interesting methods have been developed which are both rapid and simple. In this paper a number of practical techniques are presented which have proved useful in light and electron microscopy.
A fluorescence histochemical study of ketosteroids in gonadal and adrenal tissue of the rat
Authors: SMITH W. N. ADAMS , STOWARD P. J. 
Published: November 2011

SYNOPSISSections of formalin‐fixed gonads from normal rats, and adrenals and ovarian transplants from normal and castrated rats, were treated with salicylhydrazide (after pretreatment with methylhydrazine and sulphobenzaldehyde) and examined for fluorescence before and after mounting in alkali. Sites containing ketosteroids demonstrable in this way are described. Evidence is presented which suggests that luteinized thecal cells of non‐cyclic ovarian transplants may secrete androgens.Ovarian tissue which has been transplanted to male rats castrated at birth behaves as in the normal female (Pfeiffer, 1936; Yazaki, 1960; Harris, 1963, 1964). Its activity does not appear to depend on the adrenal, and castration of the newborn male rat does not lead to any obvious histological change in the adrenal (Adams Smith, 1966). However, production of androgen has been observed, using biological criteria, in ovaries grafted into the ears of castrated mice (Hill, 1937a, b) and rats (Deanesly, 1938). It therefore seemed worthwhile investigating the ketosteroid content of such tissues histochemically. In this paper the histological distribution of two different types of ketosteroid in gonads of normal rats, in adrenals of normal and castrated male rats and in ovarian transplants in the eyes of male rats (either castrated at birth or at two months of age, or with intact testes) will be described. The ketosteroids were detected histochemically by condensing them with salicylhydrazide (after pretreatment with methylhydrazine and sulphobenzaldehyde) and then observing the fluoresence they emit before and after treatment with alkali (Stoward & Adams Smith, 1964).
A tale of two mRNA degradation pathways mediated by RNase E
Authors: Bouvier Marie , Carpousis Agamemnon J. 
Published: November 2011

SummaryRNase E is an essential endoribonuclease with a preference for RNA substrates with 5′‐monophosphate ends. Primary transcripts, which have 5′ triphosphate ends, are thus protected from RNase E. Their conversion to 5′‐monophosphate transcripts by RppH is a prerequisite for RNase E‐mediated processing and degradation. 5′‐monophosphate recognition involves binding to a subdomain in the catalytic core of RNase E known as the 5′ sensor. There are, however, transcripts that can be attacked directly by RNase E in a 5′‐end‐independent pathway. Direct entry involves elements outside of the catalytic domain that are located in the carboxyl terminal half (CTH) of RNase E. Strains harbouring rne alleles that express variants of RNase E in which 5′ sensing (rneR169Q) or direct entry (rneΔCTH) are inactivated, are viable. However, the rneR169Q/rneΔCTH and ΔrppH/rneΔCTH combinations are synthetic lethal suggesting that the essential function(s) of RNase E requires at least one of these pathways to be active. A striking result is the demonstration that mutations affecting Rho‐dependent transcription termination can overcome synthetic lethality by a pathway that requires RNase H. It is hypothesized that R‐loop formation and RNase H cleavage substitute for RNase E‐dependent RNA processing and mRNA degradation.
Effects of Salinity and Soil–Drying on Radiation Use Efficiency, Water Productivity and Yield of Quinoa (Chenopodium quinoa Willd.)
Authors: Razzaghi F. , Ahmadi S. H. , Jacobsen S.‐E. , Jensen C. R. , Andersen M. N. 
Published: November 2011

AbstractDrought and salinity reduce crop productivity especially in arid and semi‐arid regions, and finding a crop which produces yield under these adverse conditions is therefore very important. Quinoa (Chenopodium quinoa Willd.) is such a crop. Hence, a study was conducted in field lysimeters to investigate the effect of salinity and soil–drying on radiation use efficiency, yield and water productivity of quinoa. Quinoa was exposed to five salinity levels (0, 10, 20, 30 and 40 dS m−1) of irrigation water from flower initiation onwards. During the seed‐filling phase the five salinity levels were divided between two levels of irrigation, either full irrigation (FI; 95 % of field capacity) or non‐irrigated progressive drought (PD). The intercepted photosynthetically active radiation was hardly affected by salinity (8 % decrease at 40 dS m−1) and did not differ significantly between FI and PD. Radiation use efficiency of dry matter was similar between salinity levels and between FI and PD. In line with this, no negative effect of severe salinity and soil–drying on total dry matter could be detected. Salinity levels between 20 and 40 dS m−1 significantly reduced the seed yield by ca. 33 % compared with 0 dS m−1 treatment owing to a 15–30 % reduction in seed number per m2, whereas the seed yield of PD was 8 % less than FI. Consequently, nitrogen harvested in seed was decreased by salinity although the total N‐uptake was increased. Both salinity and drought increased the water productivity of dry matter. Increasing salinity from 20 to 40 dS m−1 did not further decrease the seed number per m2 and seed yield, which shows that quinoa (cv. Titicaca) acclimated to saline conditions when exposed to salinity levels between 20 and 40 dS m−1.
Exotic species richness and native species endemism increase the impact of exotic species on islands
Authors: Walsh Jessica C. , Venter Oscar , Watson James E. M. , Fuller Richard A. , Blackburn Tim M. , Possingham Hugh P. 
Published: November 2011

ABSTRACTAim  Exotic species pose one of the most significant threats to biodiversity, especially on islands. The impacts of exotic species vary in severity among islands, yet little is known about what makes some islands more susceptible than others. Here we determine which characteristics of an island influence how severely exotic species affect its native biota.Location  We studied 65 islands and archipelagos from around the world, ranging from latitude 65° N to 54° S.Methods  We compiled a global database of 10 island characteristics for 65 islands and determined the relative importance of each characteristic in predicting the impact of exotic species using multivariate modelling and hierarchical partitioning. We defined the impact of exotic species as the number of bird, amphibian and mammal (BAM) species listed by the International Union for Conservation of Nature (IUCN) as threatened by exotics, relative to the total number of BAM species on that island.Results  We found that the impact of exotic species is more severe on islands with more exotic species and a greater proportion of native species that are endemic. Unexpectedly, the level of anthropogenic disturbance did not influence an island's susceptibility to the impacts of exotic species.Main conclusions  By coupling our results with studies on the introduction and establishment of exotic species, we conclude that colonization pressure, or invasion opportunities, influences all stages of the invasion process. However, species endemism, the other important factor determining the impact of exotic species, is not known to contribute to introduction and establishment success on islands. This demonstrates that different factors correlate with the initial stages of the invasion process and the subsequent impacts of those invaders, highlighting the importance of studying the impacts of exotic species directly. Our study helps identify islands that are at risk of impact by exotics and where investment should focus on preventing further invasions.
Free Trade in Agriculture and Global Poverty
Authors: Bussolo Maurizio , De Hoyos Rafael , Medvedev Denis 
Published: November 2011

AbstractThis paper assesses the potential impacts of the removal of agriculture trade distortions using a newly developed data set and methodological approach for evaluating the global poverty and inequality effects of policy reforms. It finds that liberalisation of agriculture and food could increase global extreme poverty by 0.2 per cent and lower moderate poverty by 0.3 per cent. Beneath these small aggregate changes, most countries witness a substantial reduction in poverty, while South Asia – where half of the world’s poor reside – experiences an increase in extreme poverty incidence owing to high rates of protection afforded to unskilled‐intensive agricultural sectors. The distributional changes are likely to be mild but exhibit a strong regional pattern. Inequality is likely to fall in regions such as Latin America, which are characterised by high initial inequality, and rise in regions like South Asia, characterised by low initial inequality.
Clonal diversity, population structure, and dispersal in the parthenogenetic moth Ectoedemia argyropeza
Authors: Menken Steph B. J. , Wiebosch‐Steeman Maria 
Published: November 2011

AbstractPopulations of the parthenogenetic moth Ectoedemia argyropeza (Lepidoptera, Nepticulidae) were studied for their clonal composition. Clones were characterized by 6 polymorphic enzyme loci. In a geographic survey 32 clones were observed among 812 individuals. Two clones were predominant, together they explained over 75% of the total variation. Relationships among clones hinted at a monophyletic origin of the species. Analysis of the life cycle and population structure indicated that E. argyropeza is a very sedentary species, with bottlenecks, drift, and passive migration as important population genetical factors moulding the variation.
Evaluation of compressive strength in the first premolars between young and elderly people: ex vivo study
Authors: de Noronha Fernando , Scelza Miriam F.Z. , da Silva Licinio E. , de Carvalho Waldimir R. 
Published: November 2011

doi: 10.1111/j.1741‐2358.2011.00583.xEvaluation of compressive strength in the first premolars between young and elderly people: ex vivo studyObjective:  This study evaluated the compressive strength of first maxillary premolars from young and elderly people.Background:  Findings have revealed that changes happening on dental structure lead to a higher susceptibility of tooth fracture.Materials and methods:  Thirty teeth were divided into four groups as follows: G I (n = 7) premolars of elderly patients with fused roots, G II (n = 8) premolars of elderly with separate roots, G III (n = 7) pre‐molars of young people with fused roots and G IV (n = 8) premolars of young people with roots separated. The roots were placed in polyvinyl chloride (PVC) cylinder and embedded in acrylic resin. Afterward, the samples were subjected to fracture by compressive strength in a universal testing machine. Loads were applied in continuous and progressive speed of 0.5 mm/min until the moment of fracture. The values found underwent statistical analysis (anovaα = 0.05).Results:  With regard to age, there was a statistical difference, the teeth of the elderly being more susceptible to fracture (p < 0.05). With regard to root morphology, no significant differences between both groups were observed (p > 0.05).Conclusion:  It was concluded that with the methodology employed, the age factor was important with regard to fracture resistance to compression.