bluuebunny/crossref_metadata_2025_split huggingface dataset:
Macronuclear Regeneration in Epistylis Articulata
Authors: Seshachar B. R. , Dass C. M. S. 
Published: April 2021

ABSTRACT
The reorganization of the macronucleus from the vegetative micronucleus is described in Epistylis articulata (Ciliophora, Peritricha). Individuals which have accidentally been deprived of a macronucleus during binary fission develop a new one from the micronucleus. In such amacronucleate animals, the micronucleus divides into two, one of them growing into a macronucleus, the other remaining as the micronucleus. The phenomenon throws new light on the relative importance of the two parts of the ciliate nuclear apparatus and brings into greater emphasis the undifferentiated nature of the micronucleus. It also establishes the possibility of de novo synthesis of DNA in the developing macronuclear rudiment.
The Ligament of Pecten
Authors: Trueman E. R. 
Published: April 2021

ABSTRACT
The ligament of Pecten maximus consists of two layers, the outermost situated along the extensive dorsal margin of the valves, the inner between them at the umbo. The former, composed largely of tanned proteins, is laminated and is somewhat similar to the outer layer of other ligaments. The inner layer is divided into three parts, a large central non-calcified structure and two lateral calcified regions attaching the former to the valves. The lateral parts resemble the entire inner layer of the ligament of most other lamellibranchs, which is generally uniformly calcified. The central region, consisting mainly of a tanned protein complex, is gelatinous in appearance and is characteristic of P. maximus and associated species. This type of structure is particularly suitable for the rapid and frequent opening of the valves, and its relatively high efficiency may be largely attributed to the non-calcified region of the inner layer.
The Use of the Interference Microscope to Determine Dry Mass In Living Cells and as a Quantitative Cytochemical Method
Authors: Davies H. G. , Wilkins M. H. F. , Chayen J. , Cour L. F. La 
Published: April 2021

ABSTRACT
The total mass M of substances other than water (the dry mass) in the living cell can be obtained from the expression M = ϕA/χ, where ϕis the optical path difference (o.p.d.) due to the cell and A its projected area. The method makes use of the fact that the refractive increments α (χ=100α) of most substances in cells are approximately the same, and independent of concentration. Values for χ have been tabulated. Inaccuracies in the measurement of dry mass due to variations in χ (using y average = 0·18) will be less than ± 10 per cent, in cells containing nucleic acids, proteins, and lipoproteins. When appreciable quantities of other substances are present the inaccuracy may be somewhat greater. When the total dry mass of living cells is determined in a medium other than water (e.g. isotonic solution), a correction term involving the thickness must be determined; this correction is often small. Optical path differences have been measured with the Dyson interference microscope, and different methods for doing this, together with the interpretation of the image in interference contrast, are discussed. The total dry masses and, in some cases, the concentrations of dry substance in a variety of biological objects including Amoebae, pollen grains at various stages of development, nuclei of cells in tissue culture, and sperm heads have been determined. In Tradescantia bracteata, during development from the microspore to the mature pollen grain, the dry mass increases by about tenfold. The dry masses of mature pollen grains were measured before and after successive digestion with ribonuclease, which removed about 4 to 14 per cent, of the dry mass, and with trypsin, after which about 40 per cent, of the original dry mass remained. In living ram sperm heads the ratio of deoxyribose nucleic acid to total dry mass determined by ultra-violet and interference microscopy respectively is 40 per cent. This is in good agreement with the value 45 per cent, obtained by bulk biochemical methods. The interference microscope has been used to measure the refractive index of cells and, hence, the concentrations of dry substances in them, by immersing them in media of different known refractive indices. The application of this method to fixed cells is discussed theoretically. In experiments on fixed ram sperm heads the expected linear relationship between o.p.d. and refractive index of the immersion medium was obtained. Data on the average concentration of dry substance in ram sperm heads, the localized refractive index, and concentration in the denatured submicroscopic particles in the head, the percentage of the head volume occupied by them, and. the geometrical thickness of the head were’obtained. : ‘ Factors affecting the accuracy of the measurements of o.p.d., such as glare in the microscope, light scatter or absorption by the object, &c., are outlined.
Refractometry of living cells part I. basic principles
Authors: Barer R. , Joseph S. 
Published: April 2021

ABSTRACT
The principles underlying a new method of refractometry of living cells are discussed. The method was evolved from the chance observation that the amoebocytes of the blood of the earthworm, examined in their own blood, appeared bright instead of dark by positive phase-contrast microscopy. This was shown to be due to the presence of dissolved haemoglobin which raised the refractive index of the medium above that of the cytoplasm. In order to determine the refractive index of the latter it was only necessary to dilute the blood until the cytoplasm became virtually invisible. Non-pigmented proteins and other high molecular weight substances have now been substituted for haemoglobin.
The nature of the initial observations suggested that if the cell could be regarded to a first approximation as being composed entirely of proteins, the cytoplasmic protein concentration could be equated to the protein concentration of the immersion medium which made the cell appear with minimum contrast. This would only be true if equal concentrations of different proteins in solution had the same refractive index. The nature of refractive index and its relationship to density are discussed and it is shown that for nearly all unconjugated proteins so far investigated the specific refraction increments (i.e. the increase in refractive index per 1 per cent, increase in concentration) have almost the same values (00185±2 per cent.). The effects of many factors such as pH, salts, temperature, wavelength, concentration, and nature of the solvent are discussed. Since living cells contain substances other than proteins the specific refraction increments of protein derivatives, lipides, carbohydrates, and salts are considered and it is shown that the presence of moderate amounts of such substances is unlikely to affect the refractive index of cells to any great extent. It is suggested that the mean specific refraction increment of protoplasm should be taken as 0018 and that this value can be used in order to calculate the solid and water content of protoplasm from values of refractive index.
The Changes of Water Distribution in Cytoplasm and Nuclear Sap during Division as Indicated by Changes in their Refractive Indices
Authors: Ross K. F. A. 
Published: April 2021

ABSTRACT
The changes in refractive index of the cytoplasm and nuclear sap of the dividing spermatocytes of Locusta migratoria were measured by the refractometric technique first employed by Barer and Ross in 1952. It was found that, while certain restricted regions behaved slightly differently, the refractive index of the greater part of the cytoplasm fell during the first part of prophase from 1·354 in the resting cell to about 1·346, and rose again steadily after the beginning of metaphase until it approximated to its original value at the end of telophase. These results did not accord very closely with previous refractometric measurements, but showed a marked agreement with a previous record of changes in viscosity made by Carlson in 1946. It is suggested that this parallel behaviour is best explained by assuming that shifts in water distribution occur in the dividing cell, and that during prophase the cytoplasm and nuclear sap become correspondingly more aqueous as the chromosomes become denser.
The Effect of Diet on Egg Maturation and Resorption in Mormoniella vitripennis (Hymenoptera, Pteromalidae)
Authors: Edwards Roy L. 
Published: April 2021

ABSTRACT
M. vitripennis females have been treated in one of the following ways: (a) fed on honey, (b) starved, (c) fed on host blood. When fed on honey the ovaries contain 22 eggs after 2 days, then a slow cycle of maturation and resorption begins so that for 16 days their condition does not change. After 16 days resorption is more rapid and by 28 days there are only 1 or 2 mature eggs. When starved, the parasites die in 5 days. Rapid resorption occurs and at death there are only 3 eggs in the ovaries. When fed on host blood, eggs mature rapidly. After 5 days the ovaries contain 40 mature eggs even though 260 have been deposited. Parasites which are then starved, resorb eggs very rapidly and die in 48 hours, but those fed on honey live for at least 8 days and rapid resorption does not occur.
The Morphology of Peripheral Nerve Terminations in the Skin
Authors: Weddell G. , Pallie W. , Palmer Elisabeth 
Published: April 2021

ABSTRACT
An account is given of the innervation of the skin from selected regions of the body in man, the rhesus monkey, and the rabbit. It is based on a critical evaluation of methylene blue and silver preparations in skin which had been treated with the enzyme hyaluronidase before removal from the body and in skin which had not thus been treated. The nerve fibres and terminals in preparations treated with hyaluronidase resemble those seen in fresh specimens of cornea under phase contrast conditions. The numerous artifacts seen in the cornea following methylene blue staining or silver impregnation, the origin of which is known, resemble those seen in specimens of skin not treated with hyaluronidase. It is shown that cutaneous nerves ultimately terminate in an arborization of fine naked axoplasmic filaments. The naked filaments always arise from ensheathed stem fibres of varying diameters and they all end freely and extracellularly in relation to a variety of tissue elements in the skin. The actual terminal filaments wherever they end in relation to the epidermis, dermal connective tissue, blood-vessels, sweat glands, hair follicles, or within capsules of epithelial cells, cannot be distinguished from one another on the basis of inherent morphological differences. Terminal filaments from neighbouring stem fibres are always intimately related to one another and to the tissues in which they lie. The stem fibres and axoplasmic filaments to which they give rise in encapsulated endings and hair follicles are so arranged that the slightest deformation of capsule or of follicle will alter the relationship of the terminal filaments to their stem fibres. Encapsulated nerve-endings may be served by more than one stem fibre but none of the terminals of these fuse with one another. Likewise, the terminals derived from individual stem fibres ending in relation to hair follicles do not enter into protoplasmic continuity with one another. The number and length of the axoplasmic filaments varies greatly from stem fibre to stem fibre. Our observations on the behaviour of the cutaneous nerve fibres and their terminals under different histological conditions provides us with a standard by which we can distinguish artifacts and thus re-evaluate the observations on cutaneous innervation which have been reported in the literature. Evidence is brought forward which suggests that the naked axoplasmic filaments derived from sensory stem fibres may be responsible for ‘flare* and other ‘nocifensor reactions’ (Lewis), in addition to and apart from their sensory functions. The relationship of these observations to the mechanism of cutaneous sensibility is discussed.
Experiments on the Mechanism of Silver Staining: II. Development
Authors: Peters A. 
Published: April 2021

ABSTRACT
The effect of a series of photographic developers on the final silver-staining picture has been investigated. Ten common developers were used, but of these only hydroquinone, chloroquinol, pyrogallol, and p-aminophenol, were found to be of general use. The other developers were either so weak in their action that the final staining was light and incomplete, or so powerful that a differentiated nerve staining was not produced.
For silver staining to be effected nuclei of reduced silver should be present in the section. These nuclei act as centres for the deposition of additional silver reduced by the developer; the additional silver may either be derived from that combined with the sections during impregnation or from the developing solution itself. Whether or not the additional silver is deposited in such a way as to produce differentiated nerve staining depends on the properties of the developer and on the composition of the developing solution. The redox- and ‘bromide’-potentials, the sulphite and hydrogen ion concentrations in the developing solution, and the protective action of the tissue components of the section all play a part in determining the final staining picture.
A new glycine-containing physical developer and a gold thiocyanate physical developer are described.
The Significance of the Presence of Pollen in the Food of Worker Larvae of the Honey-bee
Authors: Simpson J. 
Published: April 2021

ABSTRACT
1. From a study of the quantity of undigested shells of pollen grains in the gut of worker honey-bee larvae it is concluded that the larvae receive a variable quantity of pollen in their food in summer and sometimes none at all in winter.
2. Probably less than one-tenth of the nitrogen requirements of growing larvae are obtained from the pollen in their food.
The Cytoplasmic Inclusions of a Mammalian Sympathetic Neurone: A Histochemical Study
Authors: Bruce Casselman W. G. , Baker John R. 
Published: April 2021

ABSTRACT
1. The neurones studied were those of the anterior mesenteric and coeliac ganglia of immature rabbits.
2. Ectoplasm and endoplasm can be distinguished in these cells.
3. Two kinds of cytoplasmic inclusions occur. These are (a) spherical or spheroid lipid globules or lipochondria, which are confined to the endoplasm; and (b) very minute threads and granules, regarded as mitochondria.
4. A wide variety of histochemical tests was used. The results indicate that the lipo-chondria consist of galactolipid (cerebrosid) and phospholipid, though the smallest ones may perhaps consist of galactolipid only.
5. The objects regarded as mitochondria are too small for accurate investigation by in situ histochemical methods, but they give positive reactions for phospholipid and protein.
The Cytochemistry of the Amoebocytes and Intestinal Epithelium of Venus mercenaria (Lamellibranchiata), with Remarks on a Pigment resembling Ceroid
Authors: Zacks Sumner I. 
Published: April 2021

ABSTRACT
The properties of the amoebocytes and intestinal epithelium of Venus mercenaria were studied by a variety of cytochemical procedures designed to demonstrate proteins, enzymes, carbohydrates, and lipids.
The cytoplasm of the amoebocytes contains specific granules which are constantly present and which are interpreted as being atypical mitochondria. Identification of their mitochondrial nature rests on their staining with Janus green B, their positive reaction for phospholipid by Baker’s test, and the presence of dehydrogenase activity. Unlike typical mitochondria, the specific granules are eosinophil. Protein-bound carbonyl groups and disulphide and sulphydryl groups are present in both the specific granules and the cytoplasm. The sulphydryl groups may in part be associated with the presence of dehydrogenase, lipase, and serum cholinesterase. Amoebocytes also contain glycogen and a material that is resistant to diastase and positive to the periodic acid /Schiff test; this material may be a neutral polysaccharide, unsaturated lipid, or mucoprotein.
Cytoplasmic structures which are inconstantly present in amoebocytes include sudanophil droplets, neutral red vacuoles, metachromatic granules, and granules of an excretory pigment resembling ceroid. The sudanophil droplets may be stored neutral fat or lipid associated with the Golgi apparatus. The neutral red vacuoles are not preformed inclusions, but form as the dye accumulates within the cells. Metachromatic granules, which are confined solely to the intestinal amoebocytes, consist of phagocytosed intestinal mucus liberated from goblet cells.
The histochemical reactions of the columnar intestinal epithelium suggest that these cells may be active in the digestion and absorption of nutrients, since eosinophil granules, lipid droplets, alkaline phosphatase, lipase, and serum cholinesterase are present in them.
Masses of a ceroid-like excretory pigment and goblet cells containing mucus are present between the columnar intestinal epithelial cells. The pigment contains phospholipid and apparently arises as an oxidized end-product of lipid metabolism.
Phylogenetic Plasticity of Crustacean Stomatogastric Circuits: I. Pyloric Patterns and Pyloric Circuit of the Shrimp Palaemon Serratus
Authors: Meyrand Pierre , Moulins Maurice 
Published: April 2021

ABSTRACT
Recordings from the muscles of the pyloric chamber of the shrimp Palaemon display a rhythmic pattern which is either monophasic or biphasic, and is different from the triphasic pyloric pattern of large decapods. Identification of the pyloric neurones in the stomatogastric ganglion and study of their synaptic relationships indicate that the pyloric circuit of Palaemon is very similar to the pyloric circuit of large decapods. It is concluded that homologous neuronal circuits in related species, although similar in terms of their ‘wiring diagram’, are able to produce significantly different patterned outputs.
Phylogenetic Plasticity of Crustacean Stomatogastric Circuits: II. Extrinsic Inputs to the Pyloric Circuit of the ShrimpPalaemon Serratus
Authors: Meyrand Pierre , Moulins Maurice 
Published: April 2021

ABSTRACTThe rhythmic motor patterns produced by the pyloric circuit of the shrimp Palaemon are substantially different from those of large decapods, although the homologous neuronal circuits are very similar (Meyrand & Moulins, 1988). The extrinsic inputs received by the Palaemon pyloric circuit were similar, at least qualitatively, to the extrinsic inputs known to impinge upon the pyloric circuit of large decapods. These include: rhythmic inputs that descend from another oscillator (the commissural pyloric oscillator, CPO) which appears to impose its own rhythm on neurones of the pyloric circuit; and inputs that have long-lasting effects and control the expression of endogenous burst-generating properties of individual neurones within the circuit via modulatory mechanisms.The AB-PD neurones were not observed to oscillate, and so do not appear to act as pacemakers for the pyloric circuit as they do in large decapods, probably because of differences in the organization of the modulatory extrinsic inputs.It is our conclusion that differences in the control of expression of intrinsic properties of neurones of homologous (and structurally similar) circuits belonging to related species can explain how such circuits produce widely different patterned motor outputs.
Ocular Tracking of Rapidly Moving Visual Targets by Stomatopod Crustaceans
Authors: Cronin Thomas W. , Nair Jaygopal N. , Doyle Robert D. , Caldwell Roy L. 
Published: April 2021

ABSTRACTOcular tracking in two species of stomatopod crustaceans, Squilla empusa (Say) and Gonodactylus oerstedii (Hansen), was studied by presenting animals with small targets moving to their right and left. Squilla empusa showed no indication of ocular movement responses synchronized with the target’s motion, whereas Gonodactylus oerstedii often tracked the target through large angular amplitudes. The region of visual fixation in G. oerstedii is probably the ommatidial patches in line with the eyecup axis. This is suggested by the arrangement of ommatidial axes on the eye’s circumference, and by the alignment of the eyes and the rotational motions they make as they observe an approaching target. Tracking is irregular, probably because the animal pays attention to the target only intermittently. Targets are most stimulatory as they move nearly in front of an animal. Eye tracking responses become larger, more frequent and more accurate with increasingly anterior target positions. During visual tracking, the eyes perform both smooth and saccadic tracking movements. Eye movements in the size range 7·5°-15° are made to near the position of the target at movement onset, but are less accurate relative to the target’s position at the end of the movement. During visual tracking, the two eyes apparently act with complete independence. Movements of one eye are uncorrelated with movements of the other, both for extreme and central locations of the moving target. The existence of ocular independence during smooth pursuit and saccadic tracking in G. oerstedii may be possible because of the redundancy of visual fields existing in each eye, which could permit monocular measurements of distance to a viewed object. If so, each eye is capable of providing a complete description of the location of a target in space.
Behavioural Thermoregulation in the Freeze-Tolerant Arctic Caterpillar, Gynaephora Groenlandica
Authors: Kukal Olga , Heinrich Bernd , Duman John G. 
Published: April 2021

ABSTRACT
Larvae of the high arctic caterpillar, Gynaephora groenlandica (Wöcke) (Lepidoptera: Lymantriidae) spent most (60%) of their time orienting towards the sun (i.e. basking) and only 20% feeding, primarily near midday. Larvae usually basked after feeding, then either fed again or moved to a new feeding site. Basking larvae reached their highest body temperatures (Tb) of ≈30°C (≈20°C in excess of the ambient temperature) when surrounded by snow on a calm day in the midday sun. Setae significantly decreased larval cooling rates. Maximal metabolic rates were attained in basking larvae, but at body temperatures below 10°C oxygen uptake was greatly reduced. Our studies indicate that G. groenlandica larvae are behaviourally adapted to utilize available solar radiation for growth and development.
Evidence That Histamine is a Neurotransmitter of Photoreceptors in the Locust Ocellus
Authors: Simmons Peter J. , Hardie Roger C. 
Published: April 2021

ABSTRACT
The results presented here are consistent with the hypothesis that histamine is the major neurotransmitter released by photoreceptors of locust ocelli.
When histamine is injected by ionophoresis into the locust ocellar neuropile, large second-order neurones (L-neurones) hyperpolarize in a dose-dependent manner, and responses to light in these neurones are diminished in amplitude. Both histamine and the illumination of ocellar photoreceptors caused an outward current across the membrane. Hyperpolarizing potentials in L-neurones evoked by histamine had the same reversal potential as hyperpolarizing potentials evoked by photoreceptor illumi-nation. When applied ionophoretically in the ocellus, other biogenic amines, including octopamine, dopamine and noradrenaline, had no effect on the L-neurones. Both gamma-aminobutyric acid and acetylcholine, however, depolar-ized L-neurones and diminished responses to light. Curare blocked the L-neurone’s responses to histamine and light. The histamine response recovered fully. The initial peak hyperpolarizing response to increased light recovered, but the more sustained plateau hyperpolarizing potential did not. hexamethonium bromide prolonged the response of an L-neurone to histamine, and increased the tonic component of the response to light.