Showing papers by "University of Maine published in 1976"

The role of calcium in the acrosome reaction: An analysis using ionophore A23187

Abstract: The role of Ca+2 in the acrosome reaction of echinoid and mammalian sperm was investigated using the Ca+2 transporting ionophore A23187. The ionophore induced morphologically normal acrosome reactions in both types of sperm (as assessed by electron microscopic observation of echinoid sperm and phase contrast microscopic observation of mammalian sperm). In echinoids, these reactions were immediate. In the guinea pig and hamster, ionophore significantly decreased the capacitation interval; early reactions were accompanied by activation of motility. Ionophore induced reactions were affected by sperm, ionophore and Ca+2 concentrations. Since both ionophore induced and natural reactions require extracellular Ca+2, it is suggested that an influx of Ca+2 represents the initial step of the acrosome reaction. Under natural conditions, the permeability change which results in Ca+2 influx may be induced in echinoid sperm by egg jelly and may occur in mammalian sperm during capacitation. Ionophore A23187 should prove an experimentally useful drug for further study of the acrosome reaction since its effect on cells is understood, it induces synchronous reactions in a high percentage of sperm, and it conveniently reduces the capacitation interval in mammalian sperm.

Scaling of stimulus duration by pigeons

Abstract: Pigeons were presented with a series of key-illumination time periods. During these periods two response keys were lit, one by white light and the other by red or green. White-key responses changed the color on the other key and green- and red-key responses intermittently produced food. Choice responses were reinforced at either of two intervals timed from the onset of the stimulus period. Food was scheduled for green responses during the shorter interval in some stimulus periods and food was scheduled for red-key responses at the longer interval during alternate stimulus periods. The temporal location of food in the stimulus periods was varied across conditions. Across conditions, the pigeons responded on the green key until the time at which green-key responses might be reinforced had passed; then, the probability of red-key responses increased as the time approached at which red-key responses might be reinforced. In all conditions, the pigeons, changed from green-key to red-key responses at the time that was an equal relative temporal distance from the two intervals where these responses were reinforced.

Higher Education in the United States (1985-2000).

Abstract: The object of this paper is to illustrate an application of hierarchies and eigenvalues developed by the first author to the area of planning in higher education. We start with a brief discussion of the role of scenario construction in planning and follow it with a discussion of the role of hierarchies in system planning. We then summarize the eigenvalue procedure in measurement and use it to study impacts in a hierarchy. We illustrate its use in elementary examples by way of validation. Finally, we use all the fore-going ideas to construct a composite and likely future for higher education in the United States around 1985.

Annual growth patterns in the inner shell layer of Mytilus edulis L.

Abstract: INTRODUCTIONMolluscan age determination has long been the subject of both biological and paleonto-logical research (Mossop, 1922 a, b; Haskin, 1954; Merrill, Posgay & Nichy, 1965; Andrews, 1972). Several workers have listed difficulties associated with traditional methods of determining the age of an organism based upon surface shell morphology (Pannella & MacClintock, 1968; Farrow, 1971, 1972; Berry, 1971). Others, such as Craig & Hallum (1963) have attempted, with moderate success, to circumvent these problems statistically by using size-frequency relationships, but such methods are of little value in age analysis of isolated individuals. The principal difficulty encountered in shell surface analyses arises from an inability to distinguish spawning and disturbance lines from annual marks. Problems associated with this separation have been reduced over the past decade by the discovery of daily and tidal periodicity structures within the shells of numerous Recent and fossil species of pelecypods (Barker, 1964,1970; Pannella & MacClintock, 1968; Clark, 1968; House & Farrow, 1968; Farrow, 1971, 1972). The biological and paleontological significance of such growth increments have been discussed at length by Pannella & MacClintock (1968), Barker (1970), and Clark (1974). When present in continuous sequences, these periodicity structures facilitate an accurate age determination of individual specimens.

Response bias and the discrimination of stimulus duration.

Abstract: Pigeons discriminated stimulus duration in a psychophysical choice situation. Following presentation of any duration from a set of short duration (11 to 15 sec), responses on a red key were reinforced intermittently. Following presentation of any duration from a set of long durations (16 to 22 sec), responses on a green key were reinforced intermittently. Relative reinforcement rates were manipulated for choice responses across conditions. As relative reinforcement rates were varied, psychometric functions showed shifts in green-key responses at all durations. A signal-detection analysis showed that sensitivity remained roughly constant across conditions while response bias changed as a function of changes in relative reinforcement rate. Relative error rates tended to match relative reinforcement rates.

Ionophore A23187 induces acrosome reactions in sea urchin and guinea pig spermatozoa.

Abstract: Ionophore A23187, in the presence of extracellular Ca+2, induces a morphologically normal acrosome reaction in sperm of the sea urchin and precocious acrosome reaction and activation of guinea pig sperm. Increased membrane permeability to Ca+2 is responsible for initiating the acrosome reaction in both sea urchin and guinea pig sperm. In sea urchin sperm, the permeability change is brought about by egg jelly, whereas in the guinea pig sperm it accompanies capacitation.

The ultrastructure of the integument of the American eel, Anguilla rostrata.

Abstract: The morphology and ultrastructure of the lateral body integument of the leptocephalus, glass eel, pigmented elver, and adult stages of the American eel, Anguilla rostrata, were examined with light and electron microscopy. The integument consists of an epidermis separated by a basal lamina from the underlying dermis. Three cell types are present in the epidermis in all stages. Filament-containing cells, which are the principal structural cell type, are increasingly numerous at each stage. Mucous cells, which secrete the mucous that compose the mucous surface coat, are also more numerous in each subsequent stage and are more numerous in the anterior lateral body epidermis than in the posterior lateral body epidermis of the adult. Club cells, whose function is unknown, are most numerous in the glass eel and pigmented elver. Chloride cells are common in the leptocephalus which is marine and infrequent in the glass eel. They are not present in the pigmented elver and adult which inhabit estuaries and fresh-water. Lymphocytes and melanocytes are also present in some stages. The dermis comprises two layers: a layer of collagenous lamellae, the stratum compactum, and an underlying layer of loose connective tissue, the stratum spongiosum. There is a progressive increase in epidermal thickness at each stage which is paralleled by an increase in the thickness of the stratum compactum. Rudimentary scales are present in the dermis of the adult. The increase in the number of epidermal filament-containing cells, epidermal thickness and stratum compactum thickness is correlated with an increased need for protection from abrasion and mechanical damage as the eel moves from a pelagic, oceanic habitat to a benthic, freshwater habitat. The increase in mucous cell numbers is likewise correlated with an increased need for the protective and anti-bacterial action of the mucous surface coat in the freshwater environment.

Similarity of the crystal and solution structure of yeast tRNAPhe

Abstract: A comparison of the crystal and the solution structure of yeast tRNAPhe has been carried out by calculating the low field NMR spectrum from refined X-ray structure coordinates. The similarity between the computed and observed spectra show that the crystal and solution structure are virtually identical.

The Genus Massospora Entomopathogenic for Cicadas. Part. II. Biology of Massospora levispora and Its Host Okanagana rimosa, with Notes on Massospora cicadina on the Periodical Cicadas,,

Abstract: A study was made of Massospora levispora and its host, the northern cicada Okanagana rimosa , between 1962 and 1970. The northern cicada O. rimosa is morphologically and ecologically distinct from Okanagana canadensis. Although O. rimosa generally has 5 instars, it occasionally produces a supernumerary instar. The 1st and 2nd stadia each require 1 yr for development, the 3rd and 4th, 2 yr each and the 5th, 3 yr, making a total generation time of 9 years. This species is associated with a blueberry sweet-fern habitat and produces broods whereby usually the cicada is present only every 2 years. Other parasites, predators and pathogens were also investigated. The only parasitoid occuring in this cicada was a previously undescribed sarcophagid, Colcondamyia auditrix . This fly locates its host by the sound produced by the ♂ cicada. Birds and spiders constituted the most important predators. Pathogens found in the cicada nymphs were the fungus Paecilomyces farinosus and a bacterium identified as Corynebacterium okanaganae . The Massospora pathogen occurs only in the above ground population, i.e., adults. Cicadas become infected just prior to emergence by resting spores which then produce conidia; initial infection usually results in production of conidia. Adults cicadas infected by the conidia in turn normally produce only resting spores.

Physiological and behavioral responses to hypoxia and hydrogen sulfide in the infaunal asteroid Ctenodiscus crispatus

Abstract: Survival of Ctenodiscus crispatus during exposure to hypoxia (P O 2<3 mm Hg) at 5°C is greater than that of any echinoderm reported in the literature, the LT50 being 248 h; this is reduced to 236 h in the presence of hydrogen sulfide. Unlike Asterias vulgaris and A. forbesi, both of which lose the tube foot response to tactile stimulation long before death from hypoxia occurs, C. crispatus remains responsive until death. The extension of the highly protrusible epiproctal cone, which occurs in 75% of the mud stars simultaneously exposed to hypoxia and H2S, serves to maintain burrow contact with the overlying water. The rate of oxygen consumption remains constant down to an ambient oxygen partial pressure of 10 to 25 mm Hg, becoming more oxygen-dependent after prior exposure of the asteroids to hypoxia. C. crispatus exhibits a clear oxygen-debt phenomenon as well as a compensatory reduction in the residual P O 2 (oxygen partial pressure at which oxygen consumption ceases) from 2.4 to 0.2 mm Hg after hypoxic exposure.

Ecological Physiology and Genetics of the Colonizing Actinian Haliplanella Luciae

Abstract: Since its presumed origin on the Pacific coast of Asia, Haliplanella luciae (Verrill) has become distributed throughout the northern hemisphere. The dispersal of the species has been effected through attachment to oysters shipped commercially (Verrill, 1898), transportation on ship bottoms (Stephenson, 1935), and attachment to floating seaweed (Williams, 1973a). Stephenson (1935) notes that the species may appear suddenly in a locality, flourish for a time, and then die out or disappear abruptly. It exhibits classic characteristics of a colonizing species.

Overwinter Survival of Fingerling Brook Trout with Single and Multile Fin Clips

Abstract: In an evaluation of overwinter survival of fin-clipped and unmarked brook trout in a reclaimed pond in Maine, 10,000 fall fingerlings were divided into 20 treatment groups, 19 of which were marked by the removal of either single or multiple fins. Analysis of returns from creel and trap-net sampling indicated that: (1) survival of unmarked, unanesthetized trout was significantly higher than that of marked, anesthetized fish; (2) survival of trout with multiple fin excisions was lower than that of fish with single fin excisions; (3) removal of the adipose fin had little or no effect on survival; and (4) removal of a pectoral fin was no more detrimental than the removal of a ventral fin. Spring recaptures indicated that fish of all groups were equally vulnerable to both sampling methods. Overwinter survival was low for all groups.

Studies of Aedes Triseriatus Oviposition Attractants Produced by Larvae of Aedes Triseriatus and Aedes Atropalpus (Diptera: Culigidae)

Abstract: Holding waters of 4th-instar larvae of both Aedes triseriatus (Say) and Aedes atropalpus (Coquillett) are shown contain an oviposition attractant for Ae. triseriatus adults. It is demonstrated that the attractants are contained in the volatile fraction of this material. Experiments in which physical contact with the larval holding water is prevented demonstrate the importance of olfactory mechanisms in oviposition site selection. Acetone extracts of eggs of Ae. triseriatus do not contain an oviposition attractant for this species.

Internal reflection from an amplifying layer

Abstract: The reflectance of a homogeneous amplifying layer between two transparent regions is determined theoretically with the help of the Fresnel formulas. The transparent region containing the incident beam has a higher refractive index, corresponding to an internal reflection configuration. In the limit of infinite layer thickness, the reflectance is a continuous monotonic function of incident angle, greater than unity for all angles. For certain finite values of layer thickness, the reflectance has a singular point. The results explain the reported observation of a reflectance of 1000 from an excited laser dye in contact with a quartz prism.

Machiavellianism as Tough-Mindedness

Abstract: Summary Eysenck's Inventory of Social Attitudes was presented together with the 20 Mach TV items to a heterogeneous sample of 206 white American Ss. It was hypothesized that Eysenck's T dimension possesses conceptual validity and that previous studies have inadequately operationalized this variable. The present paper was designed to test the hypothesis that the Machiavellianism scale is a better measure of tough-mindedness than the scale devised by Eysenck. Factor analysis indicated two orthogonal factors best defined as social conservatism and Machiavellianism. A correlational analysis based upon total radicalism (R) scale scores suggested that R does seem to accord reasonably well with current conceptions of economic radicalism. In turn, Mach scores but not tough-mindedness (T) scores are independent of R. These findings, together with the moderate correlation between Mach and T support the authors' contention that Eysenck's second political attitudinal factor, tough-mindedness, is more appropriately de...

Matching with a trio of concurrent variable-interval schedules of reinforcement

Abstract: A trio of concurrent variable-interval schedules of reinforcement was arranged according to a changeover-key procedure, including a changeover delay of 1.5 sec. The three schedules provided a combined maximum reinforcement rate of 45 reinforcements per hour. With that restriction, the nine experimental conditions included several combinations of variable-interval schedules, sometimes including extinction. The pigeons matched relative response rate and relative time to relative reinforcement rate. Relative time appeared to match some-what better than relative response rate. Performance adjusted rapidly from one experimental condition to the next, whether the change involved two or all three schedules of the concurrent trio.

Effects of Color and Larval-produced Oviposition Attractants on Oviposition of Aedes triseriatus

Abstract: Color of oviposition site influences egg deposition by Aedes triseriatus (Say), and can interfere in experiments designed to demonstrate selection of sites containing larval-produced oviposition pheromones. Gravid females exhibit a marked preference for dark-colored oviposition sites. Selection by females of larval holding water ( LHW ) over distilled water increased as the color of the oviposition containers became lighter. Paired tests in amber containers resulted in 66% of the eggs being laid on LHW , while 34% was placed on distilled water. Much lower total oviposition occurred at green or colorless oviposition sites, but very high selectivity due to the presence of larval-produced chemicals was observed, with an avg. 96% of the oviposition occurring at green LHW sites and 98% at colorless LHW sites. Paired t -tests indicated a highly significant difference between numbers of eggs placed on LHW and distilled water substrates in all tests.

Permafrost oxygen isotope ratios and chronology of three cores from Antarctica

Abstract: Permafrost core sediments, associated with the last intrusion of the Ross Ice Shelf in the New Harbor region, were deposited in marine (0–85 m deep) as well as freshwater environments (100–125 m). Oxygen isotope ratio measurements on these cores provide palaeoclimatic information and show that the extension of the Ross Ice Shelf predates 150,000 yr BP, whereas the radiocarbon date of its retreat is about 5,800 yr b.p.

An improved electronic system for monitoring feeding of aphids

Abstract: Detailed descriptions and diagrams of an improved electronic system for recording the feeding activity of aphids are presented and compared with previous designs. The most significant improvement involves the use of a sharply tuned 20 Hz high gain amplifier for selectively amplifying the test signal while rejecting other frequencies. This amplifier design and the use of solid-state integrated circuitry has resulted in a compact monitoring unit with a high immunity to extraneous electrical interference.

Phage Typing System for Salmonella enteritidis

Abstract: A system is described for the phage typing of Salmonella enteritidis. The system was developed using a number of bacteriophages that were isolated from sewage.

Reproduction of the Grass Carp (Ctenopharyngodon Idella) Outside Its Native Range

Abstract: Grass carp (Ctenopharyngodon idella) spawned after they were introduced into the Volga, Ili, Terek, Amu-Darya, and Kuban Rivers, and the Kara-Kum Canal of the Soviet Union; the Tone River of Japan; the Ah Kung Tien Reservoir of Taiwan; the Pampangi River of the Philippines; and the Rio Balsas and the Bodegas Lake system of Mexico Natural reproduction in the United States seems likely as soon as the large numbers of grass carp released into the Mississippi River system in 1973–1975 reach sexual maturity, probably in 1978 or 1979