bluuebunny/crossref_metadata_2025 huggingface dataset:
THE SIZE, SHAPE AND DENSITY OF MARINE PHYTOPLANKTON CONCENTRATIONS
Authors: BAINBRIDGE RICHARD
Published: January 2008

Data concerning the size, shape and density of concentrations of marine phytoplankton are considered.

It is shown that patches of many shapes may occur, but that those most frequently encountered are elliptical, having the major axis four times the minor.

The patches vary in size in a continuous series from a few feet across to as much as 30 or 40 miles by 120 or 180 miles, but the mean seems about 10 by 40 miles.

Very long narrow bands or streaks are common and should be distinguished from the patches considered above. They are only a few feet in width and may form a pattern superimposed on the latter.

Diatoms at concentrations of 10 cells/mm.3 and flagellates at 50 cells/mm.3 may be found in all these patches. Much higher concentrations have been reported but more common ones are 0–5 cell/mm.3 of diatoms and 2–5 cells/mm.3 of flagellates.

Some possible origins of this pattern of distribution are briefly discussed. It seems likely that two different mechanisms are involved: the long narrow bands or streaks resulting from the aggregation of dispersed organisms under the influence of wind‐induced water movements, and the larger patches resulting from spatially restricted upwelling of nutrient rich water into the photic zone.
RESPIRATORY EVAPORATION IN BIRDS
Authors: SALT GEORGE WILLIAM
Published: January 2008

1. Many birds are capable of varying the rate of evaporative heat loss during respiration as a means of temperature regulation.

2. Respiratory heat loss becomes increasingly important as air temperatures rise. Above the body temperature of the bird it is the only means of heat loss.

3. The rate of respiratory heat loss varies from one species of bird to another. The rate is also dependent on environmental atmospheric humidity.

4. The rate of heat loss by respiratory evaporation is dependent on the difference in vapour pressure between that of the respiratory surface and of the inspired air, on the degree of saturation of the expired air, and on the volume of air expired per breath and per unit time.

5. There is a constant relation between breathing rate and heat production in the House Sparrow above the upper critical temperature.

6. Other things being equal, there is a constant relation between evaporative rate and the vapour pressure difference between the air and the evaporative surface, if one assumes that the vapour pressure of the respiratory surface is equal to that of water at the rectal temperature of the bird.

7. When variations due to differences in respiration rate, metabolic rate, atmospheric humidity and body size are excluded, in some species of birds the rate of evaporative heat loss is essentially constant at air temperatures above the upper critical temperature (the upper limit of the thermo‐neutral zone, see p. 114, footnote). In other species the rate of respiratory evaporation increases as air temperatures rise above the upper critical temperature.

8. From this evidence and other data in the literature, there appear to be four classes of species: one in which respiratory evaporation as a temperature‐regulating mechanism is unimportant or non‐existent; a second in which respiratory evaporation takes place in the lungs and air sacs and in which, at air temperatures above the upper critical temperature, increased evaporation is achieved only by an increased respiratory rate; a third in which respiratory evaporation takes place in the lungs and air sacs but the evaporative rate can be enhanced without an increase in respiratory rate; and a fourth in which evaporation takes place in the more anterior regions of the respiratory tract such as the trachea or buccal cavity.

9. These four groups are interpreted as representing various stages between two extremes of specialization. One extreme is represented by species of cold arid regions in which all or most of the tidal air passes through the lung parenchyma. Respiratory evaporation and hence heat loss is thus minimized. The other extreme is represented by species of hot humid regions in which the major function of ventilation is to provide evaporative heat loss. Respiratory gas exchange is a minor purpose and only a small fraction of the tidal air traverses the lung passages.
A QUANTITATIVE BALANCE BETWEEN SUBSTRATES AND METABOLIC PRODUCTS OF THE MAMMARY GLAND
Authors: BARRY J. M.
Published: January 2008

1. An attempt has been made to assess from published experiments, and largely for the goat, the principal compounds that are absorbed from the blood by the lactating mammary gland, the quantities of each that are absorbed during the formation of 100 ml. of milk, and the proportion of each of the major components of milk, and of the carbon dioxide expired by the gland, which is derived from each of the components of blood.

2. An assessment has first been made of which compounds of blood could, and which could not, be quantitatively significant metabolites of the gland. This has been done by calculating the maximum amount of each compound which would be available to the gland during the formation of 100 ml. of milk, from its concentration in blood together with the rate of blood flow through the gland.

3. For components of blood which could be quantitatively significant metabolites of the gland, it should be possible to discover whether or not they are absorbed in significant amounts by making arterio‐venous measurements. Those measurements which have been made are considered, and rough calculations have been made of the quantity of each compound which is absorbed from the blood of the goat during the formation of 100 ml. of milk.

4. From this information, and from the results of experiments with isotopic tracers, an attempt has then been made to assess the proportion of each of the major components of milk, and of the carbon dioxide expired by the lactating gland, which is derived from each of the components of blood.

5. It is realized that the calculations made in this article are approximate. In conclusion, possible improvements in technique are briefly considered which would enable a balance of this kind to be made accurately.
THE ONTOGENY OF THE VASCULAR CAMBIUM IN THE STEM OF SEED PLANTS
Authors: PHILIPSON W. R. , WARD JOSEPHINE M.
Published: January 2008

1. A striking characteristic of the vascular cambium is its plasticity. It may arise in any position in any tissue except the epidermis. It may function in a variety of ways, giving rise to xylem or phloem alone, or to both tissues. If both xylem and phloem are formed from the same cambium, they may be derived from opposite faces of the meristem or be combined as bundles or be mixed less regularly. One cambium may be succeeded by another and the method of functioning of successive cambia may vary. A number of these possibilities may be combined in one plant either simultaneously or at different stages of growth.

2. The mode of operation of the cambium in monocotyledons is so different from that of most dicotyledons, that it is unlikely that they can be homologous. It is probable that a cambium has been acquired independently in several lines of mono‐cotyledonous evolution, although the virtual identity of the cambium wherever it occurs in monocotyledons is remarkable. Some dicotyledonous cambia are almost equally distinctive. To distinguish these from the usual bi‐directional cambium, the term uni‐directional cambium is applied to them in this account. A uni‐directional cambium may be a primitive feature of the families Chenopodiaceae, Amarantaceae, and Nyctaginaceae, but essentially identical cambia have been acquired in the Styli‐diaceae, the Phytolaccaceae and in several independent lines within the Compositae.

3. Another feature of the cambium is the pressure of competition between its cells. This is especially evident during the early growth of a stem, when increase of circumference is relatively great. Many cells are produced by pseudo‐transverse divisions within the initial layer. These cells increase in size by intrusive growth, and many are lost. Survival has been shown to be influenced by a wide variety of factors.

4. A large number of investigations has established a pattern of variation in size of xylem elements within the tree. This reflects a similar pattern of size variation in the cambium. In broad outline this pattern is found in most trees which have been investigated, although considerably modified in timbers derived from storeyed cambia. Groups of woody plants showing other modifications of the pattern have been described.

5. The transformation of fusiform initials into ray initials and vice versa is another example of the plasticity of the cambium. The maintenance of the proportion of ray to fusiform initials characteristic of a species indicates that cambial activity is a well‐co‐ordinated and orderly process. The importance of a correct proportion of ray tissue among the longitudinal elements of the xylem is evident.
GLYCOPROTEINS IN MEMBRANES
Authors: COOK G. M. W.
Published: January 2008

1. Although the classical models of biomembranes have emphasized the lipid and protein nature of these structures, a small quantity of carbohydrate is present as glycoprotein and glycolipid in animal cell membranes. In this article an attempt has been made to indicate that such carbohydrate materials should be considered in any complete model of animal cell membranes.

2. Various techniques that have demonstrated the presence of glycoproteins in animal cell membranes have been discussed here. In particular, cell electrophoresis, especially when the measurements are combined with specific enzyme treatments of the cells, has indicated that the net negative surface charge on intact viable cells is mainly due to sialic acid‐containing glycoproteins and not as previously thought to ionizable phosphate groups associated with a complex phospholipid system.

3. Membrane‐bound antigens are complex carbohydrate‐containing macro‐molecules whose antigenic activity is principally associated with the configuration at terminal positions on the carbohydrate chains. Enzymic degradation of the glycoproteins of the intact plasma membrane of cells, especially erythrocytes, causes profound changes in the immunological behaviour of the cell.

4. Histology and electron microscopy have indicated the presence of carbohydrate at the periphery of many mammalian cells. Some workers consider that such materials are present in a ‘cell coat’ covering the plasma membrane, rather than in the membrane itself.

5. Studies on the isolation and characterization of membrane glycoproteins have indicated that small oligosaccharide units linked to O‐seryl or glutamyl residues in proteins are important structural units in plasma membranes.

6. The glycosylation of proteins takes place within the membranes of the endo‐plasmic reticulum. Studies of glycoprotein biosynthesis suggest that the cell is able to synthesize a diversity of cell‐surface structures from a relatively small number of monosaccharides.

7. Modification of the sialic acid‐containing glycoproteins of the plasma membrane affects the transport of materials in and out of cells. Glycoproteins are present in membranes other than the plasma membrane, and are therefore considered to be integral components of membranes; hence the designation ‘cell coat’, whilst useful as a descriptive term, should not be taken to indicate that glycoproteins are constituents of a functional entity separate from that of the membrane.

8. Evidence that membrane glycoproteins may act as sites of interaction between cells is discussed. The involvement of glycoproteins in such a role would explain why the cell had developed a biosynthetic process capable of producing varied surface oligosaccharide structures from monosaccharides.
THE SUBLETHAL EFFECTS OF SYNTHETIC INSECTICIDES ON INSECTS
Authors: MORIARTY F.
Published: January 2008

The synthetic insecticides have been used in steadily increasing quantities since the Second World War and are non‐specific poisons, and so pose the possibility of sublethal effects on wild populations of animals.

The organochlorine insecticides in general, and some of the cyclodienes in particular, are usually much more persistent than the organophosphorus and carbamate insecticides, both in the environment and within individual insects.

Analyses of samples suggest that traces of the organochlorines are widely dispersed over the entire globe.

Although the evidence is incomplete, all of these synthetic insecticides appear to exert their primary toxic lesion by interference with the conduction of impulses in the nervous system.

The complete pattern of events that ends in death includes the release of secondary toxins into the blood. These are probably physiologically active compounds, normally present, but liberated in excessive amounts by excessive nervous stimulation.

A condition similar to the late, paralytic, stage of insecticidal poisoning can also be produced, in Periplaneta americana, by excessive physical stimulation and there are similarities in the physiological changes caused by both types of stimuli. This suggests that a generalized stress syndrome develops after excessive nervous stimulation. However, this similarity has so far only been demonstrated for this one insect species.

Sublethal effects have so far only been looked for cursorily. Interpretation of sublethal effects is sometimes difficult; apparent differences between dosed and control individuals may sometimes be caused by selective mortality of the dosed individuals. Four main types of effect have been found.

Latent toxicity, which is evident as a reduction of longevity or of death at particular developmental stages, has been found only with organochlorines, appears to be linked with fat metabolism, and shows clearly that sublethal effects may be produced a long time after acquiring a dose of a persistent insecticide.

All types of synthetic insecticide can affect reproductive potential, and may increase or decrease the number of eggs produced. Egg fertility or development of offspring may also be affected. Reductions are sometimes caused directly by inhibition or distortion of ovary development, sometimes indirectly by reduced feeding.

The few studies on behaviour have shown that activity may increase, feeding decrease, and the acceptance threshold of sucrose be lowered.

DDT induces the formation of more detoxifying microsomal enzyme in Triatoma infestans.

I suggest that latent toxicity and some behavioural changes are probably caused by direct effects on the nervous system, but that some of the other results may be secondary effects associated with the stress syndrome. There is also the possibility of direct insecticidal action on other systems.

It is a pleasure to thank our librarian, Mrs Jean King, for her unfailing help in tracing references.
A SURVEY OF NEUROENDOCRINE PHENOMENA IN NON‐ARTHROPOD INVERTEBRATES
Authors: GOLDING D. W.
Published: January 2008

Neurosecretory phenomena are apparently ubiquitous among Metazoa.

In Hydra, neurosecretory products are probably involved in the control of growth and reproduction.

Secretory elements in the central nervous system of turbellarians probably promote fission, regeneration and reproduction.

The cerebral ganglia of nemertines are the source of a hormone which exercises an inhibitory influence on maturation of the gonads and the development of somatic sexual characteristics. A principle secreted by the ganglia and/or the associated cerebral organs controls weight regulation. A sex hormone controls sexual differentiation.

Secretory neurons may influence the production of exsheathing fluid and ecdysis in nematodes.

In nereid polychaetes, a single hormone which originates from the cerebral neuroendocrine system apparently promotes segment proliferation and inhibits maturation. However, in certain other polychaetes, contrasting endocrine mechanisms seem to operate.

In lumbricid oligochaetes, a hormone secreted by the cerebral ganglion (and possibly by other nervous centres also) promotes gonadal activity and the differentiation of somatic sexual characters. In some species the ganglion exerts an inhibitory influence on the associated processes of ‘diapause’ and posterior regeneration. The cerebral and suboesophageal ganglia are implicated in the control of osmoregulation. Cerebral neurosecretory cells in limicolous oligochaetes may influence regenerative growth and osmoregulation.

The cerebral ganglia of leeches secrete a gonadotrophic hormone.

In gastropod molluscs, hormones secreted by the cerebral ganglia, glandular ‘dorsal bodies’ and/or optic tentacles are responsible for the control of the development of the reproductive tract, and the activity of the gonads. Contrasting mechanisms are thought to operate in the different gastropod groups and there is conflicting evidence particularly with respect to the endocrine functions of the optic tentacles and the gonads. The ‘bag cells’ of the abdominal ganglion of ApZysiu secrete a hormone which induces egg‐laying. Cells in the pleural and parietal ganglia probably control osmoregulation in Lymnaea.

The optic glands of cephalopods secrete a gonadotrophic hormone, but sex hormones are apparently absent. The functional significance of the neurovenous tissues (presumptive neurosecretory complexes of unusual character) is obscure in most cases.

The radial nerves of starfish are the source of a hormone which induces the production of I‐methyl adenine by the follicle cells of the gonad. This second principle stimulates oocyte maturation and the shedding of male and female gametes.

The relevance of such information to the development of certain biological concepts and to various aspects of comparative physiology is briefly discussed.
CONVERSION EFFICIENCIES IN HETEROTROPHIC ORGANISMS
Authors: CALOW P.
Published: January 2008

1. The maximum possible efficiency at which living systems are able to convert input nutrients to their own biomass is between 70 and 80 %.

2. Conversion efficiency in bacteria, protozoa and metazoan cells in culture approximates more closely to 60%.

3. Conversion efficiency during embryonic development begins below 60% and rises above this level in the later stages.

4. Very young, post‐natal organisms have high net efficiencies; 50 to 70% in homeotherms and 50 to 80 % in poikilotherms.

5. In cellular systems, capable of proliferation, conversion efficiency is independent of food supply. This means that conversion is directly dependent on nutrient supply.

6. Control of growth at the tissue level may occur through the control of the supply of nutrients to the tissues and its entry into the cells.

7. Compensatory growth, after and during undernutrition, involves increased absorption efficiency and reduced metabolic costs.
PRODUCTION AND ROLE OF INTERFERON IN PHYSIOLOGICAL CONDITIONS
Authors: BOCCI VELIO
Published: January 2008

1. There is convincing evidence that a number of agents such as bacteria, viruses, endotoxins, foreign proteins, smokes and chemicals come into contact under physiological conditions with the lymphoid tissue associated with the gut and/or bronchial systems. Endogenous lectins and proteases may also act as mitogens on the central and peripheral immune system.

2. It is suggested that these agents act as inducers of interferon (and some also as immunogens), so that local production of interferon is turned on successively from cell to cell depending upon their responsiveness and upon the periodic inflow of inducers.

3. On the basis of a number of different features, it is proposed to distinguish between an ‘acute’ and a ‘physiological’ interferon response. In the latter, the interferon‐producing cell influences the neighbouring cells by short‐range humoral transmission (paracrine control) and possibly by cellular interaction, while the route of the general circulation is preferentially used in the former response.

4. It is suggested that the physiological interferon response, although previously overlooked, has great biological importance because production of interferon at strategic sites can maintain active defence systems essential for survival.

5. It is to be expected that the physiological interferon response, although amenable to experimental verification, may be difficult to detect. On the basis that interferon is normally absent from serum, it is suggested that most of the released immune‐type interferon is either bound by cells surrounding the site of its synthesis or catabolized locally.

6. It is postulated that the progressive decline of the physiological interferon response with increasing age may represent one of the factors favouring the insurgence of autoimmune diseases and tumours in the process of ageing. It is also suggested that the involution of the thymus may in part be due to intrathymic production of interferon induced by proteases released from macrophages.
PHYCOLOGY AND HEAVY‐METAL POLLUTION
Authors: RAI L. C. , GAUR J. P. , KUMAR H. D.
Published: January 2008

1. All heavy metals, including those that are essential micronutrients (e.g. copper, zinc, etc.), are toxic to algae at high concentrations.

2. One characteristic feature of heavy‐metal toxicity is the poisoning and inactivation of enzyme systems. Many of the physiological and biochemical processes, viz., photosynthesis, respiration, protein synthesis and chlorophyll synthesis, etc., are severely affected at high metal concentrations.

3. Some algae inhabit waters chronically polluted with heavy‐metal‐laden wastes from mining and smelting operations; Nodularia sp., Oscillatoria sp., Cladophora sp., Hormidium sp., Fucus sp. and Laminaria sp., etc., occur in metal‐rich waters. These algal forms are probably more capable of combating the toxic levels of heavy metals and this attribute is a result of physiological and/or genetic adaptations. The sensitivity or tolerance to heavy metals varies amongst different algae. The phenomena of multiple tolerance and co‐tolerance may be exhibited by some algae.

4. Heavy‐metal pollution causes reduction in species diversity leading to the dominance of a few tolerant algal forms. The primary productivity also decreases after metal supplementation.

5. The uptake and accumulation of heavy metals can be active (energy‐dependent), passive (energy‐independent), or both.

6. Heavy metals can be safely stored as intranuclear complexes by some algae. Notwithstanding this, some changes in the cell wall can enable the algae to tolerate heavy metals by checking the entry of the metals (exclusion mechanism).

7. The metal content of algae growing in a waterbody may yield valuable information for simulating heavy metal pollution: several species of Cladophora and Fucus have been extensively used for this purpose.

8. Several factors affect and determine toxicity of heavy metals to algae. At low pH, the availability of heavy metals to algae is greatly increased, as a consequence of which pronounced toxicity is evident. Hard waters decrease metal toxicity. Some ions, e.g., calcium, magnesium and phosphorus, can alleviate toxicity of metals.

9. The presence of other metals can influence toxicity of a heavy metal through simple additive effect or by synergistic and antagonistic interactions. Similarly, other pollutants can influence heavy‐metal toxicity.

10. The toxicity of heavy metals depends upon their chemical speciation. Various ionic forms of a metal characterized by different valency states, may be differentially toxic to a test alga.

11. Amino acids, organic matter, humic acids, fulvic acid, EDTA, NTA, etc. can complex with heavy metals and render them unavailable. This may eventually lead to less toxicity.

12. Heavy‐metal toxicity largely depends upon algal population density: the denser the population the more numerous the cellular sites available, leading to decreased toxicity.
THE MECHANISM OF LYMPHOCYTE‐MEDIATED CYTOTOXICITY
Authors: SANDERSON COLIN J.
Published: January 2008

1. Three classes of cytotoxic lymphocyte are discussed: thymus‐derived T cells, antibody‐dependent K cells and NK (natural killer) cells. Each of these cytotoxic lymphocytes has receptors allowing the formation of adhesions (contact) with a target cell (the cell to be killed). The type of receptor and the corresponding ligand on the target cell is different in each class. Cytotoxic T cells (and probably NK cells) react with a target cell antigen, in a manner rather like antibody‐antigen reactions (although not involving classical serum antibody). K cells have a receptor for the Fc part of immunoglobulin (IgG) and hence can make contact with antibody‐coated target cells.

2. It seems likely that all three classes of cytotoxic lymphocyte have a similar basic mechanism of killing, which is different from the membrane leakage occurring in complement‐mediated lysis. Much more information is available on cytotoxic T cells than on the other types of cell.

3. Cytotoxic T cell killing can be divided into two phases. A reversible phase in which the T cell is in contact with the target cell, but causes no apparent damage. This phase can vary from a few minutes up to several hours, when a single T cell interacts with a single target cell. If the T cell detaches or is inactivated the target cell survives. The second phase is irreversible, once the lethal event has occurred, and the target cell will progress to eventual lysis in the absence of the Tc cells.

4. The lethal event initiates a period of zeiosis (membrane blebbing) in the target cell, which is accompanied by increased effiux of 86rubidium. Cell lysis occurs at a variable time after the initiation of zeiosis, when the soluble contents of the cytoplasm burst out of the target cell. The fact that both these phases are of variable length leads to the accumulation of cytoplasmic markers (such as 51chromium) in the medium in an approximately linear fashion.

5. The nature of the lethal event is unknown, but it is suggested that it involves changes inside the target cell rather than at the target cell membrane. Remarkable long projections from the T cell (and also seen from K cells and NK cells), apparently arising as a result of the receptor‐ligand interaction, may be involved in the delivery of the lethal event.
EGG ACTIVATION AND PARTHENOGENETIC REPRODUCTION IN INSECTS
Authors: Went Dirk F.
Published: January 2008

1. Many insects reproduce by parthenogenesis. In one of the largest orders of the animal kingdom, the Hymenoptera, most of its members reproduce by arrhenotokous parthenogenesis. Egg activation in parthenogenetic animals obviously cannot be caused by fertilization of the egg. The question of what initiates egg development in parthenogenetically reproducing animals has been studied for a few insect species and is discussed in this article.

2. The grasshopper Melanoplus differentialis is one of several Orthoptera displaying accidental parthenogenesis. In this species, egg laying provides the stimulus to the completion of meiosis and start of embryonic development in unfertilized and probably also in fertilized eggs. The same holds true for the dipteran insect Drosophila melanogaster which exhibits rudimentary parthenogenesis, and for D. mercatorum showing accidental parthenogenesis. The precise way in which oviposition affects the egg is unknown.

3. The stick insect Carausius morosus reproduces by obligatory thelytoky. The triggering factor for removal of the meiotic block and initiation of embryonic development is oxygen from the air which penetrates to the egg through the micropyle immediately after oviposition. The oviposition act itself is not necessary for activation of the egg.

4. Comparative studies of the different types of oogenesis in the dipteran insect Heteropeza pygmaea show that in paedogenetically developing follicles meiotic arrest in prophase is of very short duration and a meiotic block at the end of oogenesis is absent. It is suggested that in this case triggering events for egg development are dispensable. On the other hand, under certain experimental conditions a meiotic block can be established in some of these follicles.

5. Investigations on the Ichneumonid wasp Pimpla turionellae have shown that unfertilized, male‐determined eggs ‐ and most likely also fertilized, femaledetermined eggs ‐ are activated by mechanical stress exerted on the eggs during natural or imitated oviposition. This mechanical stress, in addition, activates a streaming system which is independent of meiotic completion and nuclear multiplication. Egg activation by egg distortion is also found in the Pteromalid species Nasonia vitripennis and occurs presumably in many other Hymenoptera.

6. Carausius morosus, Pimpla turionellae and Nasonia vitripennis are species with parthenogenetic reproduction for which the natural factors responsible for the initiation of egg development have been identified. The cases of Pimpla turionellae and Nasonia vitripennis are of particular interest because of the feasibility of artificially imitating the natural activating mechanism.

7. It is concluded that apart from fertilization various events at oviposition may trigger egg development. In addition, the occurrence of rudimentary parthenogenesis in many sexually reproducing animal species suggests that sperm entry and fertilization may frequently be necessary for the continuation of egg development rather than for its initiation.
SOUND AND ITS SIGNIFICANCE FOR LABORATORY ANIMALS
Authors: GAMBLE MALCOLM R.
Published: January 2008

1. Several methods of varying accuracy have been used to assess what sounds small laboratory animals such as rodents are capable of hearing. Most rodents can detect sounds from 1000 Hz (the frequency of the Greenwich Time Signal) up to 100000 Hz, depending on the strain, with usually one or more commonly two peaks of sensitivity within this range. Dogs can detect sound most easily from 500 Hz to 55000 Hz, depending on the breed.

2. Rodents also produce sound signals as a behavioural response and for communication in a variety of situations. Ultrasonic calls in the range 22000–70000 Hz are the main communicating pathway during aggressive encounters, mating, and mothering. Similar calls have also been recorded from isolated animals associated with inactivity, rest and possibly even sleep.

3. Very loud sounds cause seizures in rats and mice, or can make them more susceptible to other sounds later in life. This effect is possible even when animals are fully anaesthetized. Sound tends to startle and reduce activity in several species of animal. Even offspring of mice that have been sound‐stressed exhibit abnormal behaviour patterns. Sounds also elicit various responses in rats from increasing aggression to making them more tolerant to electric shocks.

4. Levels of sound above 100 dB are teratogenic in several species of animals and several hormonal, haematological and reproductive parameters are disturbed by sounds above 80 dB. When rats are chemically deafened the disturbance to their fertility disappears. Lipid metabolism is disrupted in rats when exposed to over 95 dB of sounds, leading to increases in plasma triglycerides. Atherosclerosis can be produced in rabbits by similar levels of sound.

5. It has also been shown in guinea pigs and cats that hearing damage is governed by the duration as well as the intensity of the sound and is irreversible. Work on chinchillas hs demonstrated that sounds above 95 dB lead to this injury, but that sounds of 80 dB have no permanent effect on hearing sensitivity.
GASTROPOD CHEMORECEPTION
Authors: CROLL ROGER P.
Published: January 2008

(I). Gastropods use chemoreception for a wide variety of behaviours including feeding, homing, escape from predators and a variety of social and reproductive behaviours. Chemoreception is used to locate distant food sources, and to discriminate between potential foods. Responses to chemical food stimuli result from a combination of innate and experiential factors. Gastropods use chemical cues in mucus trails to home. They also home by direct olfactory orientation. Reproductive behaviour in a variety of gastropods appears to involve chemical cues. Evidence exists for pheromones controlling aggregation and mating. Numerous gastropods use chemical cues to avoid or escape from predators.

(2). Amino acids appear as likely candidates for attractants and phagostimulants for gastropod feeding. Macromolecules are probably also involved. Amino acids have also been shown to stimulate reproductive behaviours in certain gastropods, thus suggesting a pheromonal function. However, the significance of this finding to the behaviour of the organisms in the field has yet to be evaluated. Saponins have been implicated as the active substances found in sea stars that elicit escape responses of marine gastropods. Choline esters may play a homologous role in gastropod—prey and gastropod‐predator interactions.

(3). Gastropods can apparently use a number of different methods to orient to olfactory cues. These include anemotaxis or rheotaxis, klinotaxis and tropotaxis.

(4). The major chemosensory organs of gastropods have been identified. They include the anterior and posterior tentacles and lips of terrestrial pulmonates; the cephalic tentacles, the lips and buccal cavity lining, and possibly the osphradium of aquatic pulmonates; the cephalic and mantle tentacles, the anterior margin of the foot, the siphon tip, and the osphradium of prosobranchs; and the rhinophores, tentacles, oral veil and osphradium of opisthobranchs.

(5). Many of the organs named above have been examined by both light and electron microscopy. The most common anatomical organization includes bipolar primary sensory cells with cell bodies located subepithelially, and a distal dendrite extending to the free surface. Often a peripheral ganglion is located deep to the sensory epithelium. It is unclear whether axons of the sensory cells project directly to the central ganglion or by way of interneurones located in the peripheral ganglia.

(6). The dendritic specializations of the sensory cells vary considerably. Most bear cilia or a combination of cilia and microvilli. The functional significance of the variation in the types of sensory endings is unknown, although the chemosensory epithelia also respond to other sensory modalities, and it is often difficult to ascribe any one cell type to any one modality. Species‐specific variations may also complicate the picture.

(7). Prospects for and importance of future studies on gastropod chemoreception are discussed.
CONNECTIVE TISSUE CATCH IN ECHINODERMS
Authors: MOTOKAWA TATSUO
Published: January 2008

(1) Catch connective tissue is defined as the collagenous connective tissue whose mechanical properties can be changed rapidly (in seconds or minutes) under nervous control.

(2) Catch connective tissues are found in all five classes of Echinodermata. They function in tone control of the tissues and in autotomy.

(3) The change in mechanical properties occurs in viscosity.

(4) Muscle cells are not responsible for the viscosity change.

(5) The viscosity change is controlled by nervous activities. Neurosecretory‐like cells with large electron‐dense granules are found in all the catch connective tissues so far studied.

(6) The viscosity change is quite likely caused by the change in the ionic environment in the connective tissues, which alters the weak (non‐covalent) interactions between extracellular macromolecules in the tissue.
NON‐HORMONAL STIMULATORS AND INHIBITORS OF PLANT GROWTH AND DEVELOPMENT
Authors: KEFELI V. I. , DASHEK W. V.
Published: January 2008

1. Plants contain growth regulators that are non‐hormonal in nature. These regulators change in concentration during ontogeny and when applied exogenously, can either stimulate or depress growth. While the bulk of either the phenolic or terpenoid regulators are localized within the vacuole, they can also be found within other cellular compartments where they may act upon metabolic pathways, modifying either cell multiplication or elongation.

2. Non‐hormonal growth regulators may affect the synthesis and/or destruction of phytohormones, mainly indole‐3‐acetic acid (IAA). These regulators behave non‐specifically, modifying the actions of auxins, gibberellins and cytokinins upon growth.

3. A variety of both uncertainties and unresolved contradictions exist that have prevented a thorough elucidation of the mechanisms of actions of both phenolic and terpenoid regulators. These uncertainties and unresolved contradictions include lack of data regarding compartmentalization of many of the inhibitors. This raises the question of whether their intracellular concentrations become elevated sufficiently to affect metabolic pathways in vivo. Exogenously applied regulators of non‐hormonal nature usually interfere with growth only at high concentrations. Therefore, the possibility cannot be excluded that under these conditions, reactions occur within the cell that are absent in vivo.

4. The specific properties of natural non‐hormonal regulators are similar in certain respects to phytohormones. For example, both of them may be biogenetically bound within metabolic centres: shikimate (phenolics, indoles, alkaloids), bi‐benzi (coumarins) or acetate‐mevalonate (terpenoids, fluorens, sesquiterpenes, cytokinins). In addition, both non‐hormonal regulators and phytohormones exhibit biological activity in growth bioassays.

5. Non‐hormonal regulators may possess a number of useful purposes, e.g. test substances such as fusicoccin permit the investigation of the mode of action of phytohormones, specific inhibitors blocking special forms of growth and protectors of phytohormone activity in culture.
HOMING AND OLFACTION IN SALMONIDS: A CRITICAL REVIEW WITH SPECIAL REFERENCE TO THE ATLANTIC SALMON
Authors: STABELL OLE B.
Published: January 2008

(1) Based on data from the literature, the phenomenon of homing in salmonids is examined with special reference to the Atlantic salmon. Wild, native fish demonstrate an excellent homing ability, judged from percent return to the home river (1–3 %) and straying to non‐native watersheds (less than 3 % of returning fish).

(2) The homing ability in wild fish is shown to be closely related to the existence of reproductively isolated populations between and within watersheds, as demonstrated by data from salmonid ecology and biochemical genetics.

(3) Two main hypotheses have dominated the literature on salmonid homing during recent years: (a) An ‘imprinting’ hypothesis based on a process of learning of stream odours during seaward migration, coupled with sun‐orientation for open sea navigation, (b) A ‘pheromone’ hypothesis related to odours from fish and based on inheritance and the seasonal migrating schedules of discrete populations.

(4) The olfactory sense has been demonstrated as mandatory for salmonids, both in near range and open sea navigation. According to genetic, sensory and ecological aspects of homing, the pheromone hypothesis is therefore concluded to be the most appropriate.

(5) Fish produced from artificially fertilized eggs, released within native systems or transplanted, demonstrate a reduced homing ability. Since hatchery‐raised fish demonstrate a survival in sea equivalent to that of wild fish, a genetic disturbance of navigational ability has been suggested, resulting from the production of population hybrids by man.

(6) Studies made in the fields of behaviour, electrophysiology and chemistry strongly suggest that population‐specific fish odours are involved in home‐stream recognition by salmonids.

(7) An evaluation of ‘imprinting’ experiments related to artificial organic compounds reveals that: (a) the odorant properties of the applied chemicals must be questioned, (b) imprinting related to olfaction may be based on a weak theoretical foundation, (c) returns obtained in census experiments may be adequately explained through ecological interpretations, and (d) behavioural preferences obtained from exposure to non‐natural compounds may be founded on mechanisms not associated with homing.

(8) A logical link between the use of olfaction and the role of genetics in salmonid homing is emphasized, together with its practical implications for salmonid management.
Species–area curves
Authors: McGuinness K. A.
Published: January 2008

1. The species‐area curve has been studied now for more than one hundred years. In this time four hypotheses have been proposed to account for this pattern ‐ the Random Placement (or Passive Sampling) Hypothesis, the Habitat Diversity Hypothesis, the Equilibrium Theory (or Area Per Se Hypothesis), and the Disturbance Hypothesis. The Random Placement Hypothesis was the first of these and is the simplest, proposing that nothing other than a random placement of species and individuals over area is occurring. This should be considered the Null Hypothesis for species‐area studies and must be tested and rejected before any other hypothesis can be considered viable.

2. The Habitat Diversity Hypothesis explains the species‐area curve via the addition of new habitats with increasing area. It is supposed to result in a Power Function curve. It has been invoked a number of times but has not yet been shown experimentally to give rise to a species‐area curve.

3. The Equilibrium Theory proposes that species become extinct faster on small islands as a result of the lower population sizes on such islands. This is probably the hypothesis most frequently invoked to account for the species–area curve. It is also said to result in a species‐area curve of the Power Function form. Many of the tests of this hypothesis have, however, been inadequate and on only two occasions has the null hypothesis been tested.

4. The Disturbance Hypothesis also proposes that species become extinct faster on small islands, but in this case it is supposed to occur because disturbances are more frequent and more intense on these islands. This hypothesis has only rarely been considered yet it is consistent with many of the observations used to support the Equilibrium Theory. Furthermore, it has been shown experimentally, in one situation at least, to give rise to a species‐area curve.

5. Two methods exist by which the null hypothesis of Random Placement can be tested. One is based on probability calculations; the other on sampling in the field. Both methods have been successfully used to test the null hypothesis, and to demonstrate biologically interesting and meaningful patterns.

6. The existence of a Power Function curve has been taken to indicate that the Equilibrium Theory is correct. Likewise, an Exponential curve has been taken by some as indicating that Random Placement is occurring. These views can be shown, theoretically and empirically, to be invalid. The fitting of a particular type of curve does not test any of the hypotheses described.

7. Species‐area curves can be meaningfully used to measure the relative species diversity of a community, and biologically interesting patterns can be found by comparing communities in this way.

8. More intensive studies, testing the null hypothesis and performing manipulative experiments, are necessary if the processes underlying the species–area curve are to be understood.
NON‐PHOTOSYNTHETIC FIXATION OF CARBON DIOXIDE AND POSSIBLE BIOLOGICAL ROLES IN HIGHER PLANTS
Authors: BASRA AMARJIT S. , MALIK C. P.
Published: January 2008

1. Non‐photosynthetic fixation of CO2/HCO3‐ occurs both under light and dark conditions and involve the addition of carbon to substrates which in higher plants are derived originally from carbon reduced to carbohydrates during photosynthesis. Despite the endergonic nature of these carboxylations, the advantages offered seem to be sufficient to outweigh the disadvantages of energy loss.

2. Non‐photosynthetic carbon incorporation into metabolism is dealt mainly in relation to PEP carboxylase, acetyl‐CoA carboxylase, carbamoyl phosphate synthetase and phosphoribosylaminoimidazole carboxylase while other carboxylases await further characterization or discovery. The extent to which a carboxylase participates depends upon the need for products of its activity in metabolism.

3. Non‐photosynthetic carbon fixation is intricately involved in several pathways of metabolism throughout the ontogeny of plants. The roles in relation to leaf carbon metabolism, respiratory metabolism, nitrogen metabolism, lipid and isoprenoid biosynthesis, purine and pyrimidine metabolism and metabolism associated with the action of growth regulators have been described. The fixation reactions appear to be largely concerned with the production of intermediary metabolites, circumvention of energy barriers in metabolism and regulation of plant metabolism. In addition, the activity of PEP carboxylase is involved in ionic balance and pH‐stat.

4. Malate derived by way of PEP carboxylase and NAD‐malate dehydrogenase acts as an effective osmoticum and a counter‐ion for K+ accumulation in actively growing plant cells. In addition, malate may enter the TCA cycle or can be decarboxylated by cytoplasmic NADP‐malic enzyme converting NADH to NADPH. Wherever it has been sought in different plant tissues, some evidence for PEP carboxylase and metabolism of malate has always been found.

5. Almost every plant process spanning from seed development and germination to flowering and fruit‐set requires the essential participation of non‐photosynthetic carbon fixation in regulating certain metabolic and cellular functions but it does not contribute in a major way to the carbon nutrition of plants. It is largely the tissue type that appears to determine which of the roles is predominant at any one time.