On the influence of fixations on the normal hydration of rabbit cornea and the total amount of acid mucopolysaccharides in the stroma

Summary The authors studied the influence of fixations on the normal hydration of the rabbit cornea and the total amount of acid mucopolysaccharides (AMPS) in the stroma. The following fixatives were used: formol-calcium chloride at 19° C for 24 hours, formolcetylpyridinium chloride (CPC) at 19 and 28° C for 48 hours, Lillie's fixation at 19° C for 24 hours and Carnoy's fluid at 19° C for 30 minutes. The sections of the corneae were stained with Alcian blue, colloidal Fe³⁺ in the modification according to Rinehart and Abu'l Haj and with toluidine and methylene blue. The amount of AMPS was determined with the method of Rondle and Morgan and the total hydration of the stroma by weighing the corneae before and after using different fixative fluids and by calculation of obtained values on dry weight.The best results were obtained by using formol-CPC at 28° C. At the ordinary room temperature (±19° C) it was the poorest fixation, however, as the corneae in this solution became hydrated. Formol-calcium chloride was the second in the row and it was much better than Lillie's and Carnoy's fluid.The amount of AMPS in the stroma was not essentially changed by the effect of fixatives. Within 24–48 hours formol-CPC at 28° C retained the normal content and formol-calcium chloride caused the 11% decrease of AMPS maximally. The loss of AMPS after other fixatives was minimal.The intensity of staining with cationic dyes in paraffin sections was different after individual fixatives and after the kind of their application and was dependent chiefly on the state of hydration of the corneal stroma: It is impossible to interpret the results of staining reactions in terms of the quantity of AMPS as it was hitherto done.     

不同水氮条件下骆驼刺幼苗生长及氮效率变化特征

在荒漠生态系统氮沉降背景下,研究退化植被幼苗对水分和氮素变化的响应特征,对实现植被恢复和重建具有重要意义。在塔里木盆地南缘对骆驼刺（Alhagi sparsifolia）幼苗通过2年的水分（干旱、中水和湿润）和氮素（不施氮、低氮（51 mg/kg）、中氮（102 mg/kg）和高氮（306 mg/kg））添加试验,研究骆驼刺幼苗干物质累积、生物固氮和氮效率对水氮条件变化的响应。结果表明,骆驼刺幼苗不同器官的干物质累积和吸氮效率对水氮条件变化的响应因生长年份而异,但幼苗整株干物质累积和吸氮效率在2个生长年份的变化趋势却相似。在干旱条件下,骆驼刺幼苗的干物质量、吸氮效率和生物固氮量均在低氮处理下显著增加,之后随施氮量增加而降低。水氮交互可显著提高幼苗干物质累积、吸氮效率和生物固氮量,其中以中水中氮处理的效果最好。水氮添加有降低骆驼刺幼苗氮素利用效率（NUE）的趋势,但在干旱和中水条件下施氮可显著提高幼苗的生物固氮比例,然而生物固氮比例与NUE仅在第2个生长年份呈显著负相关。在2个生长年份,骆驼刺幼苗干物质量与吸氮效率和生物固氮量呈极显著正相关关系,但与NUE和生物固氮比例并无明显相关性。这表明骆驼刺幼苗主要是通过调节吸氮效率和生物固氮量来适应水氮条件变化,进而影响幼苗干物质累积。     

土壤特性对棉铃虫(Helicoverpa armigera Hübner)发生的影响及发生程度分区

统计分析表明,土壤的多种理化性质与棉铃虫的发生程度间存在着密切的关系,其中起主要作用的是土壤容重、砂粒含量和粘粒含量3个因子,其直接通径系数依次为-0.6521、0.6735和0.3456.这些因子使土壤表现出不同的粘性,决定了土壤的透气性、持水量和板结程度等,从而影响到棉铃虫幼虫人土后蛹的存活率.用上述3个因子进行聚类分析,可将通州市划分为3个棉铃虫发生区,各区域在测报和防治上应进行区别对待.     

The efficiency of aldehyde fixation for electron microscopy: Stabilization of rat brain tissue to withstand osmotic stress

Synopsis Rat brains were fixed either with glutaraldehyde (GA) or formaldehyde (FA). After 20 min or 24 h fixation the osmotic sensitivity of the tissue was tested by immersion in (a) distilled water (b) 0.15m or (c) 0.3m cacodylate buffer. GA-fixed material retained some sensitivity to osmotic stress after 20 min fixation but was entirely resistant after 24 h fixation. Ultrastructural preservation was good after only 20 min GA-fixation, provided that the subsequent treatment was with isotonic solutions. The fixation with FA was less efficient and slower. Dark neurons and other artifacts were commonly seen after the 20 min fixation with FA. Prolongation of the FA-fixation overnight gave markedly better preservation, but however, never equivalent to that with GA.     

Spatial remapping in the primate visual system

Summary The lateral geniculate body performs a spatial remapping operation. This remapping may help to preserve the apparent distance of objects under symmetrical eye movements, thereby stabilizing the appearance of visual space. In addition, a related, and perhaps more basic function of the geniculate remapping may be to increase the efficiency of the neural matrix which encodes depth information. For distant fixation, the majority of cells in this cortical matrix would be responsive to crossed disparities, but for near fixation, many of these same cells might be converted into uncrossed disparity detectors. Two types of models for the geniculate are presented, together with supporting evidence: (1) a quantitative psychophysical model describing its steady-state properties, and (2) a qualitative neurophysiological model describing the function of the geniculate laminae.This work was supported by the U.S. Air Force under contract No. AFORSR-F 44620-67-C0085. Supplementary funding was received from NASA and NIMH under grants Ns G 496 and MH 05673 awarded to Prof. H.-L. Teuber, Chairman, Dept. of Psychology, M. I. T., Cambridge, Mass.     

Non-exchangeable binding of ammonium and amino nitrogen by Norway spruce raw humus

Summary The capacity of an originally acid Norway spruce raw humus to fix isotopically labelled ammonium and amino nitrogen in a form resistant to cold 1N HCl treatment was studied. The amount fixed was determined after a reaction period of 24 hours (the humus pretreated with propylene oxide), using the amount of labelled N in the HCl-leached humus residue as a basis for calculating the amount of added N fixed. The nitrogen sources used were ammonium chloride, glycine and cyanamide. It was found that the fixation of added ammonium and glycine N was exceedingly low in the H⁺-saturated raw humus (pH 3.3–3.4), but the fixation rate was rapidly increased by increasing the pH during the aerobic incubation. Maximum fixation was obtained at a final pH of 10–11. Within the acid range the fixation was constantly higher for added glycine-N than ammonium-N. On the alkaline side of the neutral point the amount of fixation tended to be similar for ammonium and glycine. In treatments with N¹⁵-labelled ammonium, it was shown that small but fully detectable amount of added N were present in the soluble organic N fraction of the HCl extract, the quantities increasing with increasing soil pH during the incubation. The fixation was increased by increasing temperature and decreased by oxidative pretreatment of the humus before the addition of N. In the nitrogen gas atmosphere the fixation figures were 40 to 50 per cent lower than for corresponding treatments in air atmosphere. When various N compounds were added in equimolar concentrations the highest fixation was recorded for cyanamide. In studying the stability of fixed N to acid hydrolysis, it was found that 54 per cent of the fixed N resisted eight hours' refluxing with 6N HCl, the corresponding figure for the native raw humus N being 19 per cent. About one third of the fixed N was liberated as ammonia during the acid hydrolysis.     

Distribution of extracellular polymeric substances in aerobic granules

Extracellular matrix provides an architectural structure and mechanical stability for aerobic granules. Distributions of cells and extracellular polymeric substances (EPS), including proteins, α- and β-d-glucopyranose polysaccharides, in acetate-fed granules and phenol-fed granules were probed using a novel quadruple staining scheme. In acetate-fed granules, protein and β-d-glucopyranose polysaccharides formed the core, whereas, the cells and α-d-glucopyranose polysaccharides accumulated in the granule outer layers. Based on these experimental findings, this study indicated that different conclusions can be obtained regarding EPS distributions when granules were stained differently. The core of phenol-fed granules, conversely, was formed principally by proteins; whereas, the cells and α- and β-d-glucopyranose polysaccharides were accumulated at an outer filamentous layer. Using a series of confocal laser scanning microscope (CLSM) images whose threshold values were determined via Otsu’s scheme, the three-dimensional distributions of cells and EPS were produced using a polygonal surface model. Structural information extracted can be applied in further development of comprehensive granule models.     

Concerted evolution of light satellite DNA in genus Mus implies amplification and homogenization of large blocks of repeats

Light satellite DNA components present in species belonging to the genus Mus and to related murids were studied using the Southern blot technique. The results show species variations in both the amount and periodic structure of the repeating units, which suggests that families of related higher-order repeats developed in a common ancestor and were then amplified and/or deleted to different extents during the subsequent evolutionary period. Although the patterns generated by a series of type B enzymes (restriction enzymes that possess sites in a limited number of segments making up the total satellite DNA) in the species closely related to the M. musculus complex were very similar, sequence analysis of cloned unit repeats in two of these species (M. musculus domesticus and M. spretoides) showed near fixation of species-diagnostic variant nucleotides. This suggests that the important amplification and homogenization events that occurred after the divergence of M. spretus must have involved large blocks of sequences.     

Zur mikroskopischen Darstellung komplementbindender Antigen-Antikörper-Komplexe mit fluoreszeinmarkiertem Antikomplement

Zusammenfassung Die vonKlein undBurkholder angegebene Methode zur fluoreszenzoptischen Darstellung gewebsgebundener Antigen-Antikörper-Komplexe mit fluoreszeingekoppeltem Antikomplement wurde in verschiedenen Punkten des Untersuchungsganges abgewandelt, um die Gewebs- und Zellstrukturen besser zu erhalten. Nach Prüfung verschiedener Verfahren der Schnittherstellung, der Schnittbehandlung mit Fixierungsflüssigkeiten und mit unterkühlten Reagenzien sowie der Wirkung autolysehemmender Stoffe, wird das Gefriertrocknungsverfahren als die geeignetste Methode für feinere morphologische Untersuchungen herausgestellt und in das vonKlein undBurkholder angegebene Verfahren unter Abänderung verschiedener Arbeitsgänge eingebaut. Das Gefriertrocknungsverfahren läßt die Fähigkeit des Antigen-Antikörperkomplexes Komplement zu binden unbeeinträchtigt; das gleiche gilt für die Fixierung von Frischschnitten mit wasserfreiem Aceton und wasserfreiem reinen Äthylalkohol.

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Summary The microscopic demonstration of complement fixation by means of a fluorescent anti-complement according to the technique ofKlein andBurkholder has been investigated from standpoint of its applicability to morphological studies. A series of modifications are tested some of which proved to be suitable for a better preservation of delicate morphological structures. Several experimental circumstances have been investigated in detail such as temperature of the labelled and unlabelled reagents, fixation of slices with different agents and several modifications with respect to the technique of cutting sections. It was found that the best results are obtained when the tissue is first lyophylized and then embedded in paraffin, cut and finally deparaffinizid by xylol. This procedure does not affected the capacitiy of the antigen-antibody-complexes to fix complement. Also fixation of fresh unfixed sections by aceton and ethylalcohol both free of water preserves the capacity to fix complement.

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Rapid cytofluorimetric determination of leaf nuclear DNA content in the polyploid seriesRanunculus marsicus (R. auricomus agg.,Ranunculaceae)

A cytofluorimetric method for DNA amount determination on nuclei released from fixed leaves has been successfully tested on samples belonging to the polyploid series ofRanunculus marsicus Guss & Ten. (sect.Auricomus). The procedure was devised to screen rapidly for different ploidy levels within topodemes and progenies.     

Quantitative assessment of symbiotic nitrogen fixation in diverse mutant lines of field bean (Vicia faba minor)

Summary Homozygous mutant lines of field bean selected for (a) improved yielding potential and (b) altered plant architecture and/or physiological response were tested for symbiotic nitrogen fixing ability under field conditions in comparison with their parent cultivar.¹⁵N-tracer techniques were applied to determine %N derived from atmosphere. Data were collected on assimilate and nitrogen accumulation and distribution among various plant parts during two stages of reproductive growth.Symbiotic nitrogen fixation was closely correlated with total plant top biomass and nitrogen yield. A similar close association was found between crop yield and nitrogen harvest index. Both harvest indices tended to be negatively correlated with stage of maturity and with the amount of N derived from air per unit of area. The generally high %N derived from symbiotic N₂ fixation and its comparatively small variability implies that this parameter may be difficult to improve inVicia faba under field conditions.It is concluded, that the main genetic potential for improving the amount of biological nitrogen fixation in this crop depends upon factors that promote high photosynthetic productivity and efficient N-use under appropriate agronomic conditions and with effective rhizobial associations. The establishment of rational ideotypes with a possitive impact on yield appears to be of practical significance for increasing the amount of symbiotically fixed nitrogen.     

Analogue of aspartate and glutamate active at synapses are attractants forEscherichia coli

Summary 1. This research was carried out to compareEscherichia coli bacteria with animals in their response tol-aspartate andl-glutamate and their analogues.2. Various analogues of aspartate and glutamate known to be neurotransmitters at synapses were shown to be attractants forE. coli.3. The amino acid sequences of the animal receptors and the bacterial receptor, however, have no detectable relationship. Based on the amino acid sequence, evolutionarily the two systems appear not to be related.     

Ultrastructure of globule leucocyte inclusions in the rat and mouse

Summary The fine structure of the globules in globule leucocytes of rat and mouse infected with various parasites has been studied. Best preservation was obtained with glutaraldehyde and subsequent osmium fixation. It is concluded that the structure of the globules is host specific. In rat, the structure is not parasite specific, but in mouse slight differences in the structure of the globules of the globule leucocyte in different experimental conditions suggest a small change in the packing of the sub-units.The authors are grateful to Professor G. M. Wyburn and Mr. R. N. C. Aitken for research facilities and advice. The work was partially financed by Agricultural Research Council Grant No. AG 17/49.     

Tyndallblau-Struktur von Federn im Elektronenmikroskop

Summary The normal development and cytology of the pineal organ in the newt, Taricha torosa has been described in detail. Particular emphasis has been placed on the origin of the initial pineal bud in the embryonic diencephalic roof, and the manner in which new pineal cells are proliferated in a zone surrounding the orifice of the developing pineal vesicle. These new cells apparently migrate into the walls of the enlarging vesicle and a certain number undergo progressive differentiation to become photoreceptor-like pineal sensory cells; the highest degree of this differentiation being obtained by cells whose processes protrude into the anterior, posterior, and lateral margins of the vesicle lumen.The well-formed, wide-lumened vesicle typical of early larval stages has thusfar not demonstrated any detectable cytological alterations under the influence of light, dark, pressure, or chemical stimulating agents we have employed. Within a few weeks, this young larval vesicle becomes flattened to assume the appearance of a more glial vascularized organ. In adult pineal organs it has been possible to observe aldehyde fuchsin-positive accumulations in the processes of supportive cells terminating near capillary walls. Other aspects of adult pineal cytology and innervation have also been considered in this report.A series of implants of embryonic pineal primordia into older larval host eye chambers and tailfins has given information on the development of vesicles in these sites under the influence of varying amounts of diencephalic roof tissue included with the grafts. A tentative hypothesis has been formulated to account for the tendency of a single primordium to differentiate into a larger than normal pineal mass when implanted into the tail mesenchyme with a moderate amount of diencephalic roof tissue. This hypothesis brings into focus the normal growth characteristics of the young organ developing from a broad initial pineal field and their possible modification under the influence of surrounding tissues during normal ontogeny.Incidental to the main purposes of the study, observations have been made on the pigment behavior of larvae carrying supernumerary pineal implants. These observations are discussed in the light of recent proposals by other authors.With technical assistance of Mr. Charles Cintron, Mr. Gary Clark, Miss Jean Ewalt, and Mr. Paul Johnson. The author has also been fortunate to have the interest and suggestions of Dr. Stuart Smith. Since a portion of this study was accomplished at the Zoological Laboratory, Utrecht, Holland, special thanks are due the members of that organization for their hospitality and technical advice.Portions of this research were supported by a post-doctoral fellowship (BF7283-C) from the United States Public Health Service, a research grant (G-14423) from the National Science Foundation, and grants from the University of Colorado Council on Research and Creative Work.     

Rank and age related feeding strategy observed through field experiments in the Koshima group of Japanese macaques

The feeding process of Japanese monkeys on soy beans which were scattered over a sandy beach on Koshima islet was studied. Younger monkeys were able to pick up more beans when 8 kg of beans were divided and given two times (“two times feeding”) than when the whole amount (8 kg) of beans was given at one time (“one time feeding”). The effect of saturation of the food intake capacity in younger monkeys at the first feeding in “two times feeding” did not appear at the second feeding one hour later. The minutely intake of soy beans (feeding speed) for each age class was analyzed. The decline of feeding speed in adult females after the peak in “one time feeding” was not related to the decline in density of beans on the ground, and this decline was caused by saturation of their food intake capacity. Adult females were divided into four classes according to their dominance rank order: high, lower-high, higher-low, and low classes. The total amount of intake in “one time feeding” was far larger in the high class than in any of the other classes. The total amount of feeding in the first feeding of “two times feeding” increased in accordance with rise in the dominance rank class, and there was no relation to rank and total feeding amount in the second feeding of “two times feeding.” Differences existed in the process of feeding between the rank classes. The feeding speed of the low class was as high as that of the high class on the curve of minutely intake, while the low class stopped feeding much earlier than the high class. The lower-high class displayed a low feeding speed, and stopped feeding the latest. The order of the duration to stay and to feed in the feeding area was lower-high > high > higher-low > low, and this order did not change under the three different feeding conditions, “one time feeding,” and the first and second feedings of “two times feeding.” Adolescent females tended to stay the longest duration in the feeding area among all age classes. Both the lower-high class females and adolescent females had an unstable social status in the Koshima group, and their social status affected their feeding behaviors. The feeding behaviors were similar in attitude depending on social status, and are considered to be maintained for a fairly long time. The feeding strategy of the lower-high class, in staying a longer duration in the artificial feeding area, and departing later, may be effective under the artificial feeding conditions, but it may be a bad strategy in a natural habitat where the food is not so clumped as in artificial feeding, and where choice of other food patches is possible. The above results agree well with previous reports for the Koshima group, indicating that the rank of the lower-high class females was unstable (Mori et al., 1989), and that their reproductive success was low (Watanabe et al., 1992).     

A new nitrogen-fixing bacterium: Derxia gummosa nov. gen. nov. spec.

Summary A vigorously nitrogen-fixing bacterium was isolated from a West Bengal soil. Cells from young cultures on nitrogen-deficient agar medium appear as rods measuring approx. 3–6x1.0–1.2 ., with rounded ends and homogeneous cytoplasm. Older cells contain big refractile bodies representing vacuoles and fat deposits and show a wide variation in shape. Short motile cells with a single polar flagellum arise in liquid medium with combined (ammonia) nitrogen. The Gram reation is negative and endospores are not formed.The organism is aerobic but catalase-negative. It grows rather feebly in sugar-free protein media, but in nitrogen-deficient media it produces ah heavy and extremely tenacious growth, of a characteristic uneven appearance on agar and changing from white to dark red-brown. Glucose, fructose, ethanol, glycerol, mannitol and sorbitol are the best sources of carbon. Acid but no gas is formed from several carbohydrates. Nitrogen fixation is slow but may amount to 20–25 mg. per gram glucose or mannitol supplied. Molybdenum stimulates nitrogen fixation strongly and cannot be replaced by vanadium.Various forms of combined nitrogen, especially glutamic acid, are assimilated more readily than free nitrogen. Growth can be initiated within aPh-interval from approx. 5 to 9; growing cultures may be acidified to Ph 4.5 or less.The organism is morphologically, culturally and serologically different from Azotobacter and Beijerinckia and is regarded as representing a new genus.     

Scanning electron microscopic studies of cilia

Summary A simple method for the preparation of ciliated epithelia for study with the scanning electron microscope is described. Ciliary groups are well preserved and it is possible to discern individual cilia and work out their numbers and orientation. Following scanning electron microscopical study some of the material was prepared for transmission electron microscopy and the ultrastructure of the tissue was found to be surprisingly well preserved. The tracheal epithelium of the rabbit, the olfactory epithelia of the goldfish and the rabbit, and the sensory epithelia in the statocyst of a cephalopod mollusc were examined with the scanning electron microscope to demonstrate the possibilities of the method. Acknowledgements. We would like to thank Professor J. Z. Young for his continued interest and support. The scanning electron microscope was purchased with a grant provided by the Science Research Council to Dr. Boyde, Mr. R. Willis helped in the initial stages of the study, Mr. G. Savage provided help with the goldfish material, Mr. S. Waterman provided much photographic assistance, and Mrs. N. Finney the secretarial assistance.     

Frequent duplication and deletion events in the 5S RNA genes and the associated spacer regions of theTriticeae

The 5 S DNA units from 15 grasses in theTriticeae were analysed at the DNA sequence level. Four units carried duplications near the 3-end of the 5 S RNA gene with 3 of the duplications centred on the same base pairs as a duplication previously reported byGerlach & Dyer. The fourth duplication was located 3 downstream from the gene, in the spacer region. Apparent deletions were very frequent when units of the different grasses were compared and it was clear that these deletions did not extend into a 75 bp spacer region upstream from the 5 S RNA gene. This 75 bp region also tended to be more conserved between the grasses as compared to the high level of sequence change in the rest of the spacer region. — Phenetic relationships were established between the grasses using the sequence data. The relationships were generally consistent with the data from other parameters and, in addition, showed that two Australian grasses were closely related to the other Northern hemisphere genera examined. The data concerning the Australian grasses is discussed in relation to the isolated nature of Australia.     

Growth inhibition ofMicrococcus pyogenes by manganese and riboflavin

Summary Riboflavin, in the presence of manganese, inhibited the growth ofMicrococcus pyogenes var.aureus. The inhibitory action was shown to be dependent upon aerobiosis, and was characterized predominately as a prolongation of the lag phase. Increasing concentrations of either manaanese or riboflavin, in the presence of a constant quantity of the other, enhanced the inhibitory effect. Ultra-violet irradiation of riboflavin reduced its toxic capacity in proportion to the amount of riboflavin degraded. Riboflavin-5-phosphate was equally as inhibitory as riboflavin. Ferrous iron was capable of a non-stoichiometric antagonism at low concentrations of riboflavin and/or manganese. Suported, in part, by a research grant (E-605) from the National Institutes of Health, U.S. Public Health Service. A preliminary report has appeared (Ramsey andWilson, 1956).     

Development of the acrosomic system of the spermatozoon in the Norwegian lemming (Lemmus lemmus)

Summary An electronmicroscopic study on the development of the acrosome system of the spermatozoon in the Norwegian lemming (Lemmus lemmus) has been performed. The proacrosomal granules were found to be few and to consist of a dense center and a less dense periphery, and the acrosomal vesicle to contain stainable material of the same structure but of lower density than that of the acrosomal granule. Like in the guinea pig, two zones of different density exist throughout acrosome development and are visible also in mature spermatozoa. A large osmiophilic formation consisting of saccular, tubular, and lamellar structures, was found between the apex of the condensed nucleus and the acrosome and was identified as perforatorium.We are greatly thankful to Dr. Antti Telkkä, and Mr. Mauri Nyholm, M. Sc. for expert advise in electronmicroscopy and Mr. P. Lehtimäki for photographic help. For the supply of the lemmings we are indebted to Prof. K. Lagerspetz, and Mr. O. Hissa, M. Sc. This work is related to a series of studies on the biology of the Norwegian lemming (for previous works see Asp et al.).