bluuebunny/crossref_metadata_2025 huggingface dataset:
Nucleolar changes in differentiating myoblasts
Authors: Ross K. F. A.
Published: April 2021

Unlike most embryonic cells, myoblasts do not normally divide when they undergo differentiation to form ‘muscle straps’ and subsequently muscle fibres. Their nuclei retain their individuality, and consequently this material is particularly suitable for studying the fate of nucleolar material during a process of cell differentiation.

Measurements were therefore made with an interference microscope on the nucleoli of living chick myoblasts in tissue culture preparations ; and values for their volume, dry mass, and % solid content were obtained at three distinct stages of the differentiation process, the uninucleate stage, the binucleate stage, and the multinucleate stage. It was found that the nucleoli of binucleate myoblasts had, on the average, less than half the dry mass and less than half the volume of the nucleoli of the uninucleate cells. The changes in the volumes of the nucleoli were especially striking, and it was subsequently demonstrated, by means of sequences of photomicrographs of myoblasts in developing cultures, that, during the process of association and probable fusion of two uninucleate myoblasts to form a binucleate cell, one or more of the nucleoli can be observed to shrink visibly in their linear dimensions.

As an explanation of these results it is suggested that, during the process of differentiation and tissue building characterized by the association and apparent fusion of two myoblasts, relatively large amounts of RNA or RNP may pass from the nucleoli into the cytoplasm so that the nucleolar material becomes temporarily depleted ; and that subsequently, after the cells have joined, this regains its former level. Some support for this suggestion was provided by the finding that the mean values for the dry mass and volume of the nucleoli in the multinucleate myoblasts were intermediate between those of the uninucleate and binucleate myoblasts, because the multinucleate cells are the product of both recent and less recent fusions of cells.
Chitin lamellogenesis in locust cuticle
Authors: NEVILLE A. C.
Published: April 2021

The organization and functions of cuticular lamellae, a structural feature common to all arthropod skeletons, have been studied by growth experiments analysed with the polarizing light microscope. Use has been made of the daily incremental growth of locust solid endocuticle, in which morphogenesis of chitin lamellae (lamellogenesis) can be experimentally altered by varying light and temperature at the time of deposition. Locust endocuticle is all deposited after ecdysis and is composed of alternating night zones (lamellate) and day zones (non-lamellate), distinguishable morphologically, histochemically, mechanically, and morphogenetically. Chitosan tests, confirmed by chromatography, show that the lamellae contain chitin. Endocuticle grown in constant light at constant temperature is non-lamellate; it still contains the same proportion of chitin as normally lamellate cuticle, indicating that lamellogenesis is mainly a periodic process of permanent change in organization of chitin crystallites, occurring at deposition.

Lamellogenesis in solid cuticle is independent of chitin synthesis and of chitin pore-canal fibril formation. Swelling, mechanical, and form-birefringence tests combined with histological observations show that lamellate cuticle is structurally more highly organized but less well oriented than non-lamellate cuticle. One possible function of lamellae is in stabilizing the three-dimensional chitin framework. Normally in night conditions each chitin lamella is individually determined within about 30 min, and lamellae are continuous over large areas of cuticle. The structure and formation of chitin lamellae in locust solid and rubber-like cuticles are compared. Threedimensional birefringence analysis of the locust hind tibia has revealed three chitin components: (1) chitin lamellae with the chitin crystallites oriented predominantly parallel to the plane of the cuticle surface ; (2) chitin pore-canal fibrils, running radially through the cuticle; (3) chitin fibrils oriented longitudinally along the leg axis. Of these, the lamellae and longitudinal fibrils can be morphogenetically altered by suitable techniques.
The Phylogeny of the Stomach-Infusorians of Ruminants in the Light of palaeontological and parasitological Data
Authors: Dogiel V.
Published: April 2021

1. The members of the family Ophryoscolecidae exhibit several (5) grades of progressive evolution.

2. An analysis of distribution of different species and genera of Ophryoscolecidae indicates the course of evolution of the family in the several branches of Ruminants where these Infusorians have been sufficiently studied; these branches are: family Camelidae and families Cervidae and Bovidae.

3. A comparison of the distribution of different Ophryoscolecidae with the palaeontological occurrence of their hosts leads to the conclusion that the genera of Ophryoscolecidae arose at different periods, the more complicated ones appearing later than the simpler.

4. The genera Entodinium and Anoplodinium seem to date from the Eocene, while Eudiplodinium and Epidinium appeared only in the Oligocene; the genus Ostracodinium is of a still later descent, and may have arisen in the Miocene. The latest of all to differentiate were the genera Opisthotrichum, Polyplastron, Ophryoscolex, and Caloscolex, belonging to the fourth and fifth, that is, to the highest grades of morphological complexity. Their origin cannot be traced farther back than the end of the Miocene or the beginning of Pliocene.

5. These conclusions are supported by the differences in feeding habits of different Ophryoscolecidae. The more specialized feeding on cellulose-particles has been developed in the higher Ophryoscolecidae, the lower members of the group (Entodinium and Anoplodinium) exhibiting a more diversified diet, combined sometimes with predaceous habits.

6. The need for a study of the yet unknown Infusorian fauna of Lama, and especially of Giraffidae, is emphasized, and some suggestions as to the origin of an aberrant genus of Ophryoscolecidae (Troglodytella from anthropoid apes) are given.
The Use of Basic Dyes and Ribonuclease for the Cytochemical Detection of Ribonucleic Acid
Authors: BRACHET J.
Published: April 2021

1. Basic dyes (methyl green/pyronin, and toluidin blue), in conjunction with ribonuclease, may be used to detect the cytochemical localization of ribonucleic acid. This technique has been examined critically.

2. The fixative used is important and results vary with different materials. It is suggested that Zenker and Serra fixation should be compared in preliminary investigations. Unexplained anomalies arise in the use of frozen-dried material.

3. Details are given of the methods of use of ribonuclease and of the dyes, and a general technique is given for preliminary investigations.

4. It is concluded that there is a general parallelism between intensity of staining with basic dyes and content of ribonucleic acid, but there is no evidence yet available to justify the use of such staining for the quantitative estimation of ribonucleic acid.
A Note on the Nematocysts of Corynactis viridis
Authors: PICKEN L.E. R.
Published: April 2021

A study of the change in arrangement of the barbs on the thread of the large holotrichous glutinant nematocysts of Corynactis viridis during discharge shows that the wall of the tubular thread undergoes anisometric dilatation. Together with observations on the dilatation of the thread in capsules ruptured in an aqueous medium, this strongly suggests that discharge of the thread is due to an intrinsic swelling mechanism: the tubular thread itself swells anisometrically. Though the intrinsic mechanism of discharge operates at the tip only of the discharging thread, swelling of the capsular fluid and elasticity of the capsule-wall must also play a part in normal discharge. While it has not as yet been possible to determine the optical characteristics of the wall of the undischarged thread (because of the strong birefringence of the barbs), the observed birefringence of the discharged thread indicates an anisotropy of structure such as anisometric swelling would lead us to expect.
Nuclear Transplantation in Amoebae. II: The immediate results of transfer of nuclei between Amoeba proteus and Amoeba discoides
Authors: Lorch I. J. , Danielli J. F.
Published: April 2021

1. A description is given of a method for replacing the original nucleus of an amoeba by a nucleus from another amoeba. This method has been used to study transfers of nuclei within a species (homotransfers) and between species (heterotransfers). The species used were A. proteus and A. discoides.

2. Removal of the nucleus from an amoeba inactivates the animal, so that movement is sporadic and unco-ordinated, digestion ineffective, and death results after 10—20 days.

3. Renucleation results in reactivation with both homo-and heterotransfers. Reactivated homotransfers normally are able to divide and form mass cultures. Heterotransfers are less often able to divide and very seldom form mass cultures.

4. Amoebae taken at random from a mass culture divide after an interval which appears to be composed of a lag t; in which the processes leading to division are inactive, followed by an interdivision period id during which preparation for division is active. Experiments are given showing the effect of nuclear transfer on Z; and td.

5. After heterotransfer nuclei of either species may grow and divide in foreign cytoplasm. Before the first division after heterotransfer a cytoplasmic effect on nuclear size is observable, and after the first division the cytoplasm has a dominant effect in determining nuclear diameter.

6. When curves are plotted of the frequency of occurrence of nuclei of various diameters in pure cultures, maxima are found in the curves characteristic of the species. After nuclear transfer the cytoplasm and nucleus both have a strong influence in determining the position of the maxima.

7. Studies of the form assumed by heterotransfers show that, although there is a measurable influence of the nucleus on the form soon after transfer, this influence disappears almost entirely in 6-12 days, after which the determination of form is almost entirely cytoplasmic.

8. The results given under points 4, 5, 6, and 7 are based on the study of animals immediately after transfer and for the subsequent two divisions only. Longer-term effects will be discussed in another paper.
The Tinctorial Behaviour of Human Mast Cells
Authors: Montagna William , Eisen Arthur Z. , Goldman Allen S.
Published: April 2021

Mast cells in the skin differentiate from perivascular fibroblasts. The cells nearest the walls of the blood-vessels contain mostly sparse and small mast granules; in those farther removed from the blood-vessels the granules are more numerous and coarse. With weak solutions of toluidine blue, mast granules reveal maximal chromotropy at pH 5·0. At lower pH values not all of the granules stain; at higher ones the granules and the intergranular cytoplasm stain progressively more orthochromatically. After digestion with ribonuclease and staining with toluidine blue buffered to pH 4·0 or 5·0 the mast granules are cherry red and all traces of orthochromatic staining are abolished; when stained at pH 6·0 or above, however, the cytoplasm and the granules attain a strong blue stain as if they had not been digested in the enzyme. Preparations fixed in Helly’s fluid may be washed in running water overnight and the mast granules show no diminution in chromotropy. The same sections may be stained, destained, and stained again at any desired pH with excellent results. Both the cytoplasm and the granules are Schiff-reactive, but the granules stain more intensely than the background. Sections stained with the periodic acid/Schiff technique and subsequently stained with toluidine blue reveal the mast granules brilliantly metachromatic, suggesting that the metachromatic and the Schiff-reactive substances, although co-existent, may be in fact separate elements. Mast granules, according to these tinctorial reactions, then, may contain 4 substances: (a) a protein cytoskeleton stainable with toluidine blue buffered to pH 6·0 or above; (b) some ribonucleic acid removable with ribonuclease and stainable with toluidine blue buffered to pH 5·0 or below; (c) an acid mucopolysaccharide which stains metachromatically ; and (d) a Schiff-reactive substance.
Dermal Nerve-endings in Rana and Bufo
Authors: Whitear Mary
Published: April 2021

In the skin of Rana and of Bufo there are certain coarse medullated nerve-fibres which give off unmyelinated branches dividing repeatedly to form richly varicose endings at various levels, but mainly in the stratum spongiosum of the dermis. There is no capsule. These fibres are of a type distinct from those medullated fibres which end freely in the epidermis. Their function is discussed: it is possible that they are fast nociceptive fibres.
Refractometry of Living Cells: Part III. Technical and Optical Methods
Authors: Barer R. , Joseph S.
Published: April 2021

Full details are given in this paper for carrying out the measurement of the refractive index of living cells by the method already discussed in Parts I and II of this series (Barer and Joseph, 1954, 1955). The method of preparing and storing immersion media is described as well as the dialysis technique used for adjusting pH, and in certain cases salt concentration. Methods of measurement applicable to single cells and to cell populations are discussed. It is shown that the numerical results can be used to obtain the concentration of solids, concentration of water, total wet mass and density, and concentrations in terms of wet weight of tissue. The underlying optical principles are discussed in some detail.
The structure of the germinal epithelium of the fowl testis with special reference to the presence of multinuclear cells
Authors: Lake P. E.
Published: April 2021

The effects of histological fluids on the cells of the germinal epithelium of the fowl testis have been studied with a view to confirming the fact, evident from studies of living cells, that the formation of multinuclear cells in the process of spermatogenesis is a normal occurrence. It is considered that in the most rapidly dividing germ-cells the cytoplasm is not in a very concentrated state and the usual methods of fixation, by diffusing fluids into the testis, result in disruption of the cytoplasm, especially in multinuclear cells. Methods of fixation were selected which preserved the latter in sufficient numbers to follow their development. It appears that the two secondary spermatocyte nuclei, produced after the first meiotic division of the primary spermatocyte, tend to remain together forming a binucleate cell, which becomes four-nuclear after the second meiotic division. These nuclei, now haploid, are capable of frequent multiplication within the cell before each, then designated a spermatid, eventually becomes transformed into a spermatozoon. The significance of post-meiotic multiplication is discussed.
Muscle Receptor Organs in Grasshoppers and Locusts (Orthoptera, Acrididae)
Authors: Slifer E. H. , Finlayson L. H.
Published: April 2021

A pair of muscle receptor organs is present in each of the abdominal segments from the first to the tenth in the Acrididae. They are associated with the dorsal longitudinal muscles and each consists of a single, heavily encapsulated sensory neurone with numerous dendrites which end on a long, slender muscle-fibre which has its origin near the anterior end of the segment and is inserted on the anterior border of the segment next posterior to it.
Internal Structure of Avian Melanin Granules : An Electron Microscope Study
Authors: Carr J. G.
Published: April 2021

The black melanin granule of the Brown Leghorn male is a separate particle of complex structure, differing from the brown granules of the female, chick down, and Rhode Island Red.

It is feasible to study the granules in the electron microscope directly in the intact feather.
A Perfusion Chamber for Cinemicrographic Studies
Authors: Paul John
Published: April 2021

A perfusion chamber is described which eliminates most of the difficulties encountered with other chambers.
Properties of Slime-Mould Amoebae of Significance for Aggregation
Authors: Shaffer B. M.
Published: April 2021

When all available food has been consumed, the amoebae of Dictyostelium and Polysphondylium aggregate towards collecting centres; this movement involves chemotaxis. Just after they have finished feeding, the amoebae adhere little or not at all to one another if they come in contact; they do not secrete the chemotactic agent acrasin, and cannot orient in an acrasin gradient. Later they become able to respond to an acrasin gradient, if this is great enough. In the absence of one, they may be sufficiently adhesive to form loose amorphous associations, or, depending on the species and the environment, still be quite separate. Amoebae with similar properties may be released by the spontaneous break-up of aggregated masses. In some species, amoebae that are unaggregated may lose their sensitivity to acrasin after a few hours. The elongated amoebae attracted to a source of acrasin may condense into streams. Stream amoebae move at varying speeds; they adhere strongly to others of the same species and to a variable extent to those of different species. They secrete the acrasin characteristic of their own species. Along a stream, there is often no continuous centrifugal decrement in secretion, as far as can be detected. The amoebae in it can be guided by the direction in which their adherent neighbours are flowing, though if they are exposed to an adequate acrasin gradient they will respond to it. Commonly, an adjacent stream or a centre planted beside them is not strong enough to attract them, unless they are freed to some extent from the influence of their neighbours, especially those ahead of them. Except for their being effectively non-motile and more nearly isodiametric, the amoebae in a centre are similar to those in a stream and may secrete acrasin at much the same concentrations as these do. With both types, there may be short-term fluctuations in secretion, and in at least one species a long-lasting decrease. The dimensions and gross appearance of an aggregation at the population densities used are partly determined by the time intervals over which the amoebae become acrasin-sensitive and centres are initiated, and by the relationship between these.
The Size of Living Bacteria
Authors: Ross K. F. A.
Published: April 2021

The difficulties involved in the direct measurement, by eyepiece-micrometer or from photomicrographs, of small microscopic objects such as living bacteria are discussed. The accuracy with which this can be done is limited by the numerical aperture of the optical system and the wavelength of light used. With visible light it is scarcely possible to determine the dimensions of an object more accurately than to the nearest O’4 μ. It also seems probable, from the nature of the diffraction pattern at the edges of images of objects of circular cross-section such as bacteria, that direct measurement of the width of the image will tend to give an underestimate of the true width of the object.

An interference microscope enables thickness measurements to be made that are not subject to these particular limitations, because with it, the phase-change in the light passing through the middle of a bacterium can be measured very accurately. This phase-change is proportional to the product of the refractive index of the bacterium minus that of the mounting medium, and its true thickness.

Two methods were used to determine the mean thickness of the living bacilli in a number of different cultures of Lactobacillus bulgaricus. With the first, the mean refractive index of the bacilli was measured directly by the method of immersion refractometry first used by Barer and Ross (1952), and phase-change measurements were made on the bacilli mounted in dilute saline. Their mean thickness was calculated from these measurements. With the second method, phase-change measurements were made on the bacilli mounted in saline and also mounted in protein solutions with refractive indices ranging from 1·365 to 1·376; and, from these, both their mean thickness and their mean refractive index were calculated.

The phase-change measurements were made with a Smith interference microscope and half-shade eyepiece (manufactured by Messrs. Charles Baker).

The values for the mean thickness of the living L. bulgaricus from 14 different cultures obtained by the first method ranged from 1-13 μ to i·23 μ·, and those from 9 different cultures obtained by the second method ranged from 1 ·02 μ to 1 · 14 μ. The mean refractive indices of the latter calculated by the second method agreed very closely with that obtained by immersion refractometry, and differed by a maximum of o·oo9 in all the cultures measured. It therefore seems unlikely that the mean thickness measurements obtained by either method are wrong by more than about ±o·1 μ.
The Origin of the Metazoa and the Stigma of the Phytoflagellates
Authors: Fauré-Fremiet E.
Published: April 2021

It is well known that in various phytoflagellates one of the flagella is connected with the eye-spot or stigma. In the case of Chromulina psammobia the more differentiated structure of the eye-spot+flagellum complex seems analogous to that of a retinal rod with its connective cilium binding the external segment and the cell-body.

It is tempting to draw a parallel between this finding of comparative cytology and a hypothesis on the origin of Metazoa proposed first by J. R. Baker, and subsequently by A. C. Hardy.
A Simultaneous Coupling Azo Dye Technique Suitable for Whole Mounts
Authors: Lewis P.R.
Published: April 2021

A method based on the familiar coupling azo dye technique has been devised for the study of enzyme distribution in thick specimens. Its application to the study of esterase distribution in whole tadpoles of Xenopus laevis is described in detail. It can also be used to show the distribution of alkaline phosphatase, both in Xenopus tadpoles and in limbs dissected from chick embryos. It has proved useful in embryological studies both for teaching and for research.
Observations on the Developmental Cytology of the Fundic Region of the Rabbit’s Stomach, with Particular Reference to the Peptic Cells
Authors: Menzies Gordon
Published: April 2021

1. The first oxyntic cells, differentiating from a non-mucoid cell, appear on the 23 rd day of the foetal life of the rabbit.

2. Bowie-positive granules appear in most epithelial cells during foetal life, reach a maximum on the 27th day, and then almost disappear before birth.

3. The first peptic cells containing Bowie-positive granules appear a few hours after birth. They increase after the end of the first week until the adult condition is reached.

4. During the first 4 weeks of postnatal life the pepsinogen granules contain a mucinogen component. This is lost between the fourth and sixth weeks. The loss starts in cells at the base of the glands and proceeds up the tubules towards the crypts.

5. Pepsinogen granules containing a mucinogen component are strongly eosinophil.

6. The first ‘mature’ peptic granules, that is ones that are Bowie-positive, PAS-negative and non-eosinophil, appear at the fourth week of postnatal life.

7. Mucous neck-cells (of Bensley) begin to appear at the end of the sixth week of postnatal life. Their development is being further investigated.
The Cytoplasmic Inclusions of Nyctotherus macropharyngeus: Histochemical Studies
Authors: Dutta G. P.
Published: April 2021

The cytoplasm of Nyctotherus macropharyngeus contains lipid bodies, mitochondria, and carbohydrate bodies. The lipid bodies consist of neutral lipids, most probably triglycerides, and protein. The mitochondria are rod-shaped. The carbohydrate bodies are formed by the coalescence of smaller spheres, which appear to arise in close association with the mitochondria. The external part of the smaller spheres is PAS-positive.
The osmotic pressure and saline content of the blood of Petromyzon Fluviatilis
Authors: Galloway T. McL.
Published: April 2021

The composition of the body fluids of the most primitive Craniata, namely the cyclostomes, is of considerable general interest in relation to the theory advanced by Bunge in 1894 and by Macallum in 1904 that the saline composition of vertebrate blood is related to the saline composition of the primitive sea from which they originally emerged. This theory has recently been criticised by Pantin (1931), who has reviewed the literature of the subject.
Stimulation of Neuritic Outgrowth in an Undamaged Molluscan Interneurone
Authors: Allison P. , Benjamin P. R.
Published: April 2021

Axotomy of neurones from a variety of invertebrate groups induces sprouting and regrowth of neuritic processes (reviewed by Anderson, Edwards & Palka, 1980). However, direct surgical damage is not a necessary prerequisite for inducing sprouting. For instance, Altrup & Kolde (1982) and Bulloch (1984) showed that damage to non-neural tissue could induce sprouting and Pitman & Rand (1981) showed that neural lesions can cause dendritic outgrowth of an undamaged insect neurone. We report here that a similar phenomenon to the latter occurs in the gastropod mollusc Lymnaea stagnalis. We have previously shown that lesioning the axon of the giant pedal interneurone (RPeDl) induces sprouting and subsequent recovery of synaptic connectivity (Allison & Benjamin, 1985; Benjamin & Allison, 1985). Here similar techniques were used to lesion the Lymnaea CNS, but instead of crushing connectives containing the axon of RPeDl, we lesioned a part of the CNS not occupied by RPeDl processes. This induced limited, but statistically significant, increases in the number of processes in the posterior three ganglia of the CNS, when normal and lesioned preparations were compared.
Control of Rectal Gland Secretion in the Dogfish (Squalus Acanthias) : Steps in the Sequence of Activation
Authors: Erlij D. , Rubio R.
Published: April 2021

We measured the venous and arterial pressure, as well as the rate of secretion and content of cyclic AMP and high energy phosphate compounds, of the rectal gland of the anaesthetized dogfish, Squalus acantinas (L.). Intravenous infusion of isotonic solutions produced a very large increase in the rate of secretion by the rectal gland. The increase in secretion was preceded by an increase in venous blood pressure, but arterial blood pressure was not modified. Injections of small doses of veratridine stimulated gland secretion when given in the vicinity of the heart but not when given in the dorsal aorta. During volume expansion the creatine phosphate and ATP content of the gland were markedly reduced, while ADP and AMP as well as cyclic AMP content were increased. We conclude that: (a) volume expansion leads to the release of a message that activates adenyl cyclase in the gland; (b) the increased venous pressure may be the initial signal in the sequence that leads to the release of the activating messenger; (c) there is a receptor mechanism in the atrial and cardiac region that triggers the sequence that activates glandular secretion; (d) the reduction in the content of high energy phosphate compounds during volume expansion is caused by an increase in energy expenditure, probably due to gland secretion.
Exoskeletal Strain: Evidence for a Trot–Gallop Transition in Rapidly Running Ghost Crabs
Authors: Blickhan R. , Full R. J. , Ting L.
Published: April 2021

Equivalent gaits may be present in pedestrians that differ greatly in leg number, leg design and skeletal type. Previous studies on ghost crabs found that the transition from a slow to a fast run may resemble the change from a trot to a gallop in quadrupedal mammals. One indication of the trot–gallop gait change in quadrupedal mammals is a distinct alteration in bone strain. To test the hypothesis that ghost crabs (Ocypode quadrata) change from a trot to a gallop, we measured in vivo strains of the meropodite of the second trailing leg with miniature strain gauges. Exoskeletal strains changed significantly (increased fivefold) during treadmill locomotion at the proposed trot–gallop transition. Maximum strains attained during galloping and jumping (1000×10−6–3000×10−6) were similar to the values reported for mammals. Comparison of the maximum load possible on the leg segment (caused by muscular tension) with the strength of the segment under axial loading revealed a safety factor of 2.7, which is similar to values measured for jumping and running mammals. Equivalent gaits may result from similarities in the operation of pedestrian locomotory systems.
The Physiology of Bottlenose Dolphins (Tursiops Truncatus): Heart Rate, Metabolic Rate and Plasma Lactate Concentration During Exercise
Authors: Williams Terrie M. , Friedl W. A. , Haun J. E.
Published: April 2021

Despite speculation about the swimming efficiency of cetaceans, few studies have investigated the exercise physiology of these mammals. In view of this, we examined the physiological responses and locomotor energetics of two exercising adult Tursiops truncatus. Oxygen consumption, heart rate, respiratory rate and post-exercise blood lactate concentration were determined for animals either pushing against a load cell or swimming next to a boat. Many of the energetic and cardiorespiratory responses of exercising dolphins were similar to those of terrestrial mammals. Average heart rate, respiratory rate and oxygen consumption for dolphins pushing against a load cell increased linearly with exercise levels up to 58kg for a female dolphin and 85kg for a male. Oxygen consumption did not increase with higher loads. Maximum rate of oxygen consumption ranged from 19.8 to 29.4 ml O2 kg−1 min−1, which was 7–11 times the calculated standard metabolic rate of the dolphins. Blood lactate concentration increased with exercise loads that exceeded . The maximum lactate concentration was 101.4 mgdl−1 (11.3mmol l−1) for the male, and 120.6 mgdl−1 (13.6mmol l−1) for the female. When swimming at 2.1ms−1, heart rate, respiratory rate and post-exercise blood lactate concentration of the dolphins were not significantly different from values at rest. The cost of transport at this speed was 1.29±0.05J kg−1 min−1. The energetic profile of the exercising bottlenose dolphin resembles that of a relatively sedentary mammal if the exercise variables defined for terrestrial mammals are used. However, the energetic cost of swimming for this cetacean is low in comparison to that of other aquatic and semi-aquatic mammals.
Dihydropyridine and Ryanodine Binding in Ventricles From Rat, Trout, Dogfish And Hagfish
Authors: Thomas Marion J. , Hamman Brian N. , Tibbits Glen F.
Published: April 2021

In the adult mammalian heart, the majority of Ca2+ required for contraction is released from the sarcoplasmic reticulum (SR) via the Ca2+-release channel or ryanodine receptor (RyR). Such release is dependent upon a relatively small influx of Ca2+ entering the cell across the sarcolemma (SL) by means of the L-type Ca2+ channel or the dihydropyridine receptor (DHPR). In lower vertebrates, there is indirect evidence suggesting that Ca2+ influx across the SL may be sufficient to support contraction in the absence of Ca2+ release from the SR. This apparent difference in myocardial excitation–contraction (E–C) coupling was investigated further by determining DHPR and RyR densities in ventricular homogenate preparations from rat, trout, dogfish and hagfish. DHPR Bmax values (means ± S.E.M.) were highest in rat (0.30±0.01 pmol mg−1), lower in trout (0.16±0.01 pmol mg−1) and dogfish (0.27±0.03 pmol mg−1), and slightly above the level of detection in hagfish (0.03±0.01 pmol mg−1). The DHPR dissociation constants (Kd) of 40–70 pmol l−1 in these three species were of similar magnitude. RyR binding revealed both high-and low-affinity sites in all species. RyR Bmax for the high-affinity site was greatest in the rat (0.68 pmol mg−1), lower in trout (0.19 pmol mg−1) and dogfish (0.07 pmol mg−1) and lowest in hagfish (0.01 pmol mg−1). The RyR Kd1 values for the high-affinity sites were comparable in all preparations (range 12–87 nmol l−1). The quantitative expression of RyRs in these species is consistent with the relative amount of SR present as indicated in physiological experiments and electron micrographs. Taking into consideration myocyte morphology of teleost and elasmobranch species, the data are consistent with a greater reliance on Ca2+ influx across the SL during E–C coupling in lower vertebrates, although a functional role for Ca2+ release from the SR in the more active species awaits further investigation.
Performance limits of labriform propulsion and correlates with fin shape and motion
Authors: Walker Jeffrey A. , Westneat Mark W.
Published: April 2021

Labriform locomotion, which is powered by oscillating the paired pectoral fins, varies along a continuum from rowing the fins back and forth to flapping the fins up and down. It has generally been assumed (i) that flapping is more mechanically efficient than rowing, a hypothesis confirmed by a recent simulation experiment, and (ii) that flapping should be associated with wing-shaped fins while rowing should be associated with paddle-shaped fins. To determine whether these hypotheses and the results of the simulation experiment are consistent with natural variation, we compared the steady swimming performance (critical swimming speed) of four species of labrid fish (Cirrhilabrus rubripinnis, Pseudocheilinus octotaenia, Gomphosus varius and Halichoeres bivittatus) selected to form two pairs of closely related species that vary in fin shape and in the direction of fin motion. The results were consistent with expectations. Within each pair, the species with the best swimming performance also had (i) a fin shape characterized by a higher aspect ratio, a longer leading edge relative to the trailing edge fin rays and the center of fin area located closer to the fin base, and (ii) a steeper (more dorsoventral) stroke plane.
Two swimming modes in Trachymedusae; bell kinematics and the role of giant axons
Authors: Meech Matthew E. , Mills Claudia E. , Haddock Steven H. D. , Meech Robert W.
Published: April 2021

Although members of the Rhopalonematidae family (Cnidaria, Hydrozoa, Trachymedusae) are known to exhibit unusually powerful jet swimming in addition to their more normal slow swimming behaviour, for the most part, reports are rare and anecdotal. Many species are found globally at depths of 600–2000 m, and so observation and collection depend on using remotely operated submersible vehicles. With a combination of in situ video footage and laboratory measurements, we have quantified kinematic aspects of this dual swimming motion and its electrophysiology. The species included are from two Rhopalonematidae clades; they are Colobonema sericeum, Pantachogon haeckeli, Crossota millsae and two species of Benthocodon. Comparison is made with Aglantha digitale, a species from a third Rhopalonematidae clade brought to the surface by natural water movement. We find that although all Rhopalonematidae appear to have two swimming modes, there are marked differences in their neural anatomy, kinematics and physiology. Giant motor axons, known to conduct impulses during fast swimming in A. digitale, are absent from C. sericeum and P. haeckeli. Slow swimming is also different; in C. sericeum and its relatives it is driven by contractions restricted to the base of the bell, whereas in A. digitale it is driven by contractions in the mid-bell region. These behavioural differences are related to the position of the different clades on a ribosomal DNA-based phylogenetic tree. This finding allows us to pinpoint the phylogenetic branch point leading to the appearance of giant motor axons and escape swimming. They place the remarkable dual swimming behaviour of members of the Rhopalonematidae family into an evolutionary context.
Studies on the Feeding and Nutrition of Tuberolachnus Salignus (Gmelin) (Homoptera, Aphididae)
Authors: Mittler T. E.
Published: April 2021

It has generally been supposed that the uptake of large quantities of plant sap by aphids is the direct result of suction. Zweigelt (1914) has questioned this concept, and Kennedy & Mittler (1953) have thrown further doubt on the supposition that aphids are typical ‘sucking’ insects. The present paper sets out results, obtained in a study of the uptake of phloem sap by Tuberolachnus salignus (Gmelin), which may help to clarify this question.
Polarized Light and the Orientation of Two Marine Crustacea*
Authors: Bainbridge Richard , Waterman Talbot H.
Published: April 2021

Quantitative experiments are described, designed to test the hypothesis that underwater polarized light is used for orientation by aquatic animals as that of the blue sky is by terrestrial arthropods. Studied in the laboratory the littoral mysid, Mysidium gracile, was found capable of orientation relative to the e vector in a vertical beam of linearly polarized light. Statistically significant preference was shown by this animal for aligning its longitudinal axis at right angles to the plane of polarization. A secondary slight preference was shown for swimming parallel with the plane and the degree of random orientation was often high (40% mean). The littoral prawn, Palaemon northropi, when released in quiet water far enough from the bottom and the shore to prevent visual contact, was found to swim on relatively straight horizontal courses for appreciable distances in forty-one out of sixty-one tests. The mean length of these runs was 24 · 5 m., the maximum 119 m.; swimming velocities up to about 1 km./hr. were measured. The sun’s position seems to be the only directional clue not controlled in these tests, and the general direction of the runs is significantly correlated with the direction of the sun, being at right angles to it. It is thus concluded that this animal can use the sun, either directly or through the polarization pattern, as a celestial compass.
The Absorption Of Water By Plant Tissue In Relation To External Hydrogen-Ion Concentration
Authors: Pearsall W. H. , Ewing J.
Published: April 2021

In previous papers we have considered in some detail the properties of plant tissues in relation to the hydrogen-ion concentration of the external medium, and our observations have led us to regard some of those properties as being due to the behaviour of the proteins present in the tissues, and in particular to the positions of the isoelectric points of those predominant in the tissues. It is now proposed to consider the water absorption of plant tissues from a similar point of view, and to correlate the results of such a study with the data obtained when the swelling and precipitation of proteins over a pertinent range of hydrogen-ion concentration are investigated.
Nitrogen Excretion in Ascidiacea
Authors: Goodbody Ivan
Published: April 2021

The evidence for the occurrence of storage excretion in ascidians is reviewed. Most species probably store uric acid or purine bases in some form. The renal concretions of Ascidia nigra and Phallusia mammillata contain 50-60 % uric acid, the remainder of the concretion is unidentified but is non-nitrogenous and is not calcium carbonate. In Ascidiella aspersa the concretion is predominantly composed of calcium carbonate and there is no significant quantity of uric acid or purine base. Uric acid is also identified in Molgula manhattensis, Polycarpa obtecta, Pyura vittata and Herdmania momus. Storage excretion probably results from a deficiency in the uricolytic enzyme system. It is concluded that while protein metabolism is ammonotelic, purine meta-bolism is uricotelic or xanthotelic.
Studies on Salt and Water Balance inMyxine Glutinosa(L.)
Authors: Morris R.
Published: April 2021

The myxinoids are a marine group of cyclostomes whose blood shows some similarities to the sea water in Which they live, even when they are moved to more dilute environments. Reviews by Morris (1960) and more recently by Robertson (1963) emphasize that the plasma is slightly hypertonic to the environment and that during the course of ionic regulation divalent ions are reduced in the plasma relative to sea water (Smith in Cole, 1940; Robertson, 1954; Bellamy & Chester Jones, 1961). Thus the main work of ionic regulation seems to fall on the tissues themselves. Here, potassium partly replaces sodium, whilst phosphate and perhaps amino acids take the place of chlorides (Robertson, i960; Bellamy & Chester Jones, 1961). The osmotic deficit between the plasma and the tissues seems to be made up in part by unidentified organic acids and by large amounts of trimethylamine oxide which, according to Bellamy & Chester Jones, reaches concentrations comparable with those found in marine elasmobranchs.
Lateral Interaction and Transfer in the Tactile Memory of the Octopus
Authors: Wells M. J. , Young J. Z.
Published: April 2021

Blinded octopuses were trained to discriminate by touch between rough and smooth spheres, using the arms on one side only. Intact octopuses learned more rapidly than animals with the supraoesophageal brain split by a longitudinal cut. With the brain split before training no side-to-side transfer occurred. Animals operated upon in this way did not discriminate when tested on the untrained side. When intact octopuses were trained on both sides each side appeared to benefit from the experience gained by the other. The effect was difficult to evaluate because most of the errors in the experiments were due to taking the ‘negative’ object, with the result that raising the rate of training itself tends to improve performance by lowering the proportion of takes. Animals trained on one side and then split continued to discriminate on the trained side, though at a reduced level of accuracy. When tested on the untrained side the performance of these animals was variable, depending upon the exact position of the split. The best scores were made by octopuses with some trained-side tissue left in contact with the test side. Animals with exactly medial cuts continued to discriminate, though at a reduced level of accuracy. Octopuses with the untrained side damaged did not discriminate at all. Side-to-side transfer of the effects of tactile training can occur within the inferior frontal system. It can also be demonstrated to occur elsewhere in the supraoeso-phageal brain if the inferior frontal system has been split. Presumably this other pathway passes through the superior frontal/vertical lobe system. These results are considered in relation to visual experiments on interocular transfer and it is concluded that memory traces are established on both sides of the brain as a result of unilateral training.
Monosynaptic connexions between wing stretch receptors and flight motoneurones of the locust
Authors: Burrows M.
Published: April 2021

The connexions between stretch receptors of the wings and moto-neurones innervating flight muscles have been studied anatomically and physiologically. Filling with cobaltous chloride shows that the single neurone of a forewing stretch receptor has a complex pattern of branches within the mesothoracic ganglion and branches which extend into the pro- and metathoracic ganglia. The single neurone of a hindwing stretch receptor has extensive branches in the metathoracic ganglion and branches in the mesothoracic ganglion. The branches of both receptors are confined to the ipsilateral halves of the ganglia. A stretch receptor gives information about the velocity and extent of elevation of a wing. Each spike of a forewing stretch receptor causes an EPSP in ipsilateral mesothoracic depressor motoneurones and an IPSP in elevators. The connexions are thought to be monosynaptic for the following reasons. The EPSPs in the first basalar (depressor) motoneurone follow each spike of the stretch receptor at a frequency of 125 Hz and with a constant latency of about 1 msec. In a Ringer solution containing 20 mm-Mg2+ the amplitude EPSP declines gradually. The IPSPs upon elevators have similar properties but occur with a latency of 4–6 msec. The connexions therefore comprise a monosynaptic negative feed-back loop ; elevation of the wing excites the stretch receptor which then inhibits the elevator motoneurones and excites the depressors. A hindwing stretch receptor synapses upon metathoracic flight motoneurones in the same way, causing EPSPs in depressor and IPSPs in elevator motoneurones. No connexions of either fore- or hindwing stretch receptors have been found with contralateral flight motoneurones. Interganglionic connexions are made by both receptors. For example, both fore- and hindwing stretch receptors cause EPSPs upon the meso- and metathoracic first basalar motoneurones. Stimulation of the axon of a stretch receptor with groups of three stimuli repeated every 50–100 msec thus simulating the pattern which it shows during flight, causes subthreshold waves of depolarization in depressor motoneurones. When summed with an unpatterned input, the stretch receptor is able to influence the production of spikes in motoneurones on each cycle. During flight, it is expected that the stretch receptor will influence the time at which a motoneurone will spike and hence have an effect on the amplitude of the upstroke and upon the phase relationship between spikes of motoneurones.
Electronic magazine with rating system of an estimation of individual and collective work of students
Authors: Gaponenko Artiom , Golovin Andrey
Published: April 2021

«The electronic magazine with rating system of an estimation of individual and collective work of students» (EM) is developed in document Microsoft Excel with use of macros. EM allows to automate all the calculated operations connected with estimation of amount scored by students in each form of the current control. EM provides automatic calculation of rating of the student with reflection of a maximum quantity of the points received in given educational group. The rating equal to “1” is assigned to the student who has got a maximum quantity of points for the certain date. For the other students the share of their points in this maximum size is indicated. The choice of an estimation is made in an alphabetic format according to requirements of the European translation system of test units for the international recognition of results of educational outcomes (ECTS - European Credit Transfer System), by use of a corresponding scale of an estimation. The list of students is placed on the first page of magazine and automatically displayed on all subsequent pages. For each page of magazine the optimal size of document printing is set with automatic enter of current date and time. Owing to accounting rate of complexity of task EM is the universal technical tool which can be used for any subject matter.