Showing papers by "University of Maine published in 1983"

Relationships between bacteria and grain surfaces in intertidal sediments1

Abstract: Seasonal changes in total bacterial numbers and their associated mucus coatings in surficial sediments were examined. Bacterial numbers followed the temperature cycle, with highest numbers in summer. The specific surface areas of the sediments were measured rather than inferred from other granulometric properties; bacterial numbers were proportional to surface areas only for sample suites collected at the same time. Bacteria inhabited shallow depressions on sand and silt grains; they were not found on grains smaller than about 10 pm or inside smaller pores like those on weathered feldspar grains. Mucus coatings also followed a seasonal cycle, increasing in abundance and coalescence from spring into summer. These coatings accumulated clay grains, suggesting that the relationship of bacteria to surface area may be due to bacterial control of surface area rather than the reverse. Organic carbon concentrations in grain size separates of these sediments increased with decreasing size until the fine silt fraction, and decreased in the clay fraction; it is not clear, however, whether this trend is a result or a cause of bacterial colonization patterns. Particle surfaces are important habitats for sedimentary bacteria. Adsorption of nutrients to solid surfaces and an accompanying increase in bacterial biomass was demonstrated in the early laboratory work of ZoBell(1943). Subsequent measurements of bacterial numbers or metabolic activities in sediments have exhibited a strong inverse correlation with sediment grain size, implying a surface area dependence (Dale 1974; Hargrave 1972). However, this surface area dependence of bacteria has not yet been verified with direct measures of surface area. The difficulties in relating measured surface areas to other granulometric parameters have been pointed out by Mayer and Rossi (1982). Microtopography of sediment grains has also been implicated as a factor influencing bacterial colonization on sediment grains. In an optical microscope study of sand grains, Meadows and Anderson (1966) found bacteria in patches with large ’ This work was supported by NSF ISP 8011448 and NOAA Sea Grant WLRF-45. Contribution 8302 of the Maine Benthic Oceanography Group. 2 Present address: Department of LMarine Science, University of South Florida, St. Petersburg 33701. 3 To whom reprint requests should be directed. areas of bare suface between them; these patches were often found in hollows and cracks. Weise and Rheinheimer (1978) found the density of bacterial cells to be determined by microtopography, with the highest densities on subrounded or subangular grains. Frankel (1977) found that subangular to subrounded grains of hornblende supported fewer bacteria than relatively smooth biotite grains. The separated folia of the biotite grains provided a more protected habitat and consequently supported a larger population. The degree of protection seems to influence the population size of colonizing microbiota. Surface morphology affected both the total biomass and the community structure of the microbiota (including bacteria, algae, and grazers) on silica grains in a running seawater experiment (Nickels et al. 1981). Total microbial biomass was higher on grains with more surface irregularities. Smooth grains of the same size supported a lower population of procaryotes and microalgae, with an increase of microeucaryotic grazers. Extracellular exudates of bacteria have become subjects of increasing interest due to their potential roles in affecting the sedimentological and trophic status of sediments. There is, however, a limited literature describing mucus coatings on

Canopy processing of acidic precipitation by coniferous and hardwood forests in New England.

Abstract: There are several important factors that may influence how forest canopies interact with acidic deposition, including forest community species composition, phenological status, and differences in atmospheric loading of strong acids. Results from comparative throughfall chemistry studies in New Hampshire, where precipitation pH is 4.1, indicate that northern hardwood canopies produce a throughfall solution chemistry that is less acid and higher in basic cations than either direct precipitation or throughfall solutions derived from nearby subalpine balsam fir forests. Neutralization of acid precipitation in the hardwood canopy appears to occur through two major processes: ion exchange removal of free H+ by the foliage, and Bronsted base leaching from the plant canopy. Data obtained during the period of senescence preceding leaf-drop suggest a strong link between alkalinity release and potassium leaching in the hardwood canopy. Compared with the hardwood canopy, the coniferous forest canopy exhibits several distinct quantitative differences in canopy processing.

Dissolved organic materials in surface microlayers: Temporal and spatial variability and relation to sea state

Abstract: Microlayer samples were collected to assess the temporal and spatial variability of their dissolved organic materials (DOM). Dissolved organic carbon (DOC) was often enriched in microlayers but concentration differences between niicrolayers and bulkwaters were generally small. Ranges of DOC enrichments were large in oceanic samples. Enrichments diminished with increasing bulkwater DOC concentrations in coastal waters and were not influenced by wave states from Beaufort 0 to 4. Microlayer depletions of DOC occurred, but the removal processes responsible for them are unknown. UV-absorbing phenolic fractions of microlayer DOM were consistently enriched, with the enrichments described by a partitioning relationship, and showed evidence of decreasing enrichment with increasing wave states. In general, over the temporal and spatial scales considered, microlayer DOM variabilities in clean surfaces were not greater than equivalent bulkwater variabilities.

Paleolimnological reconstruction of the effects of atmospheric deposition of acids and heavy metals on the chemistry and biology of lakes in New England and Norway

Abstract: Sediment cores from nine lakes in southern Norway (N) and six in northern New England (NE) were dated by 137Cs, 210Pb and in NE also by pollen, and were analyzed geochemically and for diatoms. Cores from two N and three NE lakes were analyzed for cladocerans. 137Cs dating is unreliable in these lakes, probably due to mobility of Cs in the sediment. In Holmvatn sediment, an up-core increase in Fe, starting ca. 1900, correlates with geochemical indications of decreasing mechanical erosion of soils. Diatoms indicate a lake acidification starting in the 1920’s. We propose that soil Fe was mobilized and runoff acidified by acidic precipitation and/or by soil acidification resulting from vegetational succession following reduced grazing. Even minor land use changes or disturbances in lake watersheds introduce ambiguity to the sedimentary evidence relating to atmospheric influences. Diatom counts from surface sediments in 36 N and 31 NE lakes were regressed against contemporary water pH to obtain coefficients for computing past pH from subsurface counts. Computed decreases of 0.3–0.8 pH units start between 1890 and 1930 in N lakes already acidic (pH 5.0–5.5) before the decrease. These and lesser decreases in other lakes start decades to over a century after the first sedimentary indications of atmospheric heavy metal pollution. It is proposed that the acidification of precipitation accompanied the metal pollution. The delays in lake acidification may be due to buffering by the lakes and watersheds. The magnitude of acidification and heavy metal loading of the lakes parallels air pollution gradients. Shift in cladoceran remains are contemporary with acidification, preceding elimination of fishes.

On the moments of residual life in reliability and some characterization results

Abstract: In reliability studies, it is well known that the mean residual life function determines the distribution uniquely. In this paper we study the problem "do higher moments of residual life determine the distribution"? We show, by means of a counterexample, that one higher moment is not enough to determine the distribution uniquely. However, a method is given to determine the distribution if the ratio of two consecutive moments is known. Also it is shown that the constancy of the rth moment, for any positive real number r guarantees that the distribution is exponential. Similar problems are investigated for partial moments and it is shown that unlike truncated moments, one partial moment is enough for the determination of the distribution. Some illustrations are given to exhibit the methods.

The Influence of a Rape Victim's Physical Attractiveness on Observers' Attributions of Responsibility

Abstract: Research has provided conflicting results as to the impact of a rape victim's physical attractiveness on observers' attributions of responsibility, attributed in part to methodological considerations. The present study, employing multiple exemplars of attractiveness and multiple dependent measures of responsibility, revealed consistent evidence of an attractiveness bias among observers, with an unattractive victim being assigned greater responsibility in general for her own victimization, as well as specific behavioral and characterological blame, than an attractive victim. The un-attractive victim was also considered to have contributed to her assault by presenting a more provocative appearance than her more attractive counter-part. These biases were stronger for male observers than for females. Although the attractiveness factor differentially influenced the perceived responsibility of a victim, it did not affect attributions toward the assailant.

RNA‐DNA ratio as an index to growth in salmonid fishes in the laboratory and in streams contaminated by carbaryl

Abstract: Free nucleotides, RNA, and DNA were extracted from fish white muscle and analysed by a two-wavelength ultraviolet (UV) absorbance technique to determine their relation to growth rates in brook trout, Salvelinus fontinalis, and Atlantic salmon, Salmo salar. In the laboratory, fish given ample feed had higher growth rates than fish on restricted rations, and these growth rates were significantly correlated with RNA-DNA ratios. Wild brook trout from natural streams had higher average RNA-DNA ratios than those in the laboratory. Exposure of brook trout in one of the streams to low levels of the insecticide carbaryl (Sevin) that drifted from the spraying of nearby forests did not reduce RNA-DNA ratios.

Sex Differences in Self-Confidence: The Influence of Comparison to Others' Ability Level.

Abstract: Previous investigators have suggested that women display lower self-confidence than men in almost all achievement settings. The validity of this suggestion is assessed in an experiment testing the impact of comparison to others upon sex differences. Male and female undergraduates, who expected to cooperate in the future with a same-sex partner of high, average, or low ability, selected a difficulty level for an achievement test, completed the test, evaluated their own performance, and estimated their future partner's probable performance. As predicted, only when subjects' future partner was highly competent did women select an easier test than men, perform less well, and compare themselves less favorably to their partner. Also, women's, but not men's, self-evaluations depended upon their partner's ability level. It is concluded that sex differences are moderated by social comparison variables. Cognitive processes that may underlie such differences are discussed.

Further evidence for osmoregulation in epidermal leaf cells of seagrasses

Abstract: A comparison of the epidermal leafcell ultrastructure ofthree seagrasses, Thalassia testudinum (tropical, high salinity), Zostera marina (North temperate, moderate salinity), and Ruppia maritima (North temperate, brackish) provides confirmation for the theory that an invaginated plasmalemma-mitochondrial transport system is developed at least in part as a response to salt concentration. Cytochemical localization of presumed Cl- ion provides further evidence for the presence of a salt secretion or exclusion mechanism. Immature epidermal leaf cells communicate with each other and with mesophyll cells through numerous plasmodesmata, but during cell maturation these cytoplasmic connections are lost and the apoplastic transport system develops to replace the symplastic one. The two North temperate region seagrasses contain cytoplasmic lipids which are absent in the tropical species. Thalassia and Zostera have chloroplasts which lack starch, but stain densely for polysaccharides with thiocarbohydrazide. The polysaccharide staining is essentially negative in the chloroplasts of Ruppia, but mesophyll chloroplasts of this brackish water species contain starch. These and other cytological findings are compared with other seagrasses. IN AN EARLIER PAPER it was proposed that the epidermal leaf cells of the seagrass Thalassia testudinum are osmoregulatory (Jagels, 1973). The evidence presented to support that theory consisted of 1) demonstration of a high membrane potential, and 2) discovery of a convoluted plasmalemma with interdigitated mitochondria, analogous to structures found in other secretory cell systems. In this paper two other lines of evidence are presented in support of osmoregulation. One approach involves the ultrastructural localization of sodium or chloride ions to document salt partitioning. The other approach involves a comparative ultrastructural study, predi

Spawning of American eel,Anguilla rostrata, relative to thermal fronts in the Sargasso Sea

Abstract: Collections of recently hatched American eel leptocehali including specimens less than 5.5 mm total length suggest the following hypotheses: 1) that thermal fronts separating the northern and southern surface water masses of the Sargasso Sea form the northern limit of American eel spawning, and 2) that some feature of the surface water mass in the southern Sargasso Sea serves as a cue for adult American eels to cease migrating and begin spawning activity.

Method for determining the degree of completion and pulp yield

Abstract: A method is described for monitoring and determining the degree of completion, pulp yield, and residual lignin content in a pulping or delignification reaction. The system provides an on-line, real time, closed loop process control system for the reaction of a known quantity of wood in process liquor. The desired pulp yield is achieved by sampling the liquor during the reaction; determining the total organic carbon content of the sampled liquor; and calculating the degree of completion of the reaction and pulp yield from the process liquor total organic carbon content determination using an appropriate mathematical model. The mathematical model is based upon conservation of carbon mass in the wood or pulp and liquor during the reaction, and includes a conservation of mass equation in which the total organic carbon in the sampled liquor substantially equals the total carbon in the starting quantity of wood or pulp less the total carbon in pulp wood residue at the time of sampling the liquor. Variations of the basic system and method are described.

Interactive image query system using progressive transmission

Abstract: There is a growing need for people to browse through files of images such as satellite or medical photos, to determine which ones warrant further examination. Users located at some distance from the image archive often must use slow transmission links such as telephone lines. If an image is scanned out line-by-line, top-to-bottom, the user must often wait too long to determine whether the image is of any use. Using the Progressive Transmission Method, however, images are encoded so that during transmission the entire display shows a rough version of the image in 'fat pixels'. If the user wishes to see more detail, additional data is sent and used to refine these pixels, until the exact original image is seen. We report here on extensions of this method to the rich color imagery found in remote-sensing applications. A significant advance is the elimination of unworkably large look-up tables by using a single simple algorithm for performing the required encoding and decoding operations. The method is conceptualized in a 'transmission cone' context which assists a user in interacting with the system. The user can roam over large images, zoom to various levels of resolution, and cause specified subregions of interest in the image to fill in to full resolution, at a tremendous saving in time.

Alpha‐Chaconine and Alpha‐Solanine Content of Potato Peels and Potato Peel Products

Abstract: Twelve samples of raw and cooked potato peels from commercial potato varieties were analyzed for their α-chaconine and α-solanine content by high-performance liquid chromatography (HPLC). Raw peels contained 1.30–56.67 mg/100g peel (wet weight) α-chaconine and 0.5–50.16 mg/100g peel (wet weight) α-solanine. Raw flesh from the same potatoes contained 0.02–2.32 mg/100g flesh (wet weight) α-chaconine and 0.01–2.18 mg/100g flesh (wet weight) of α-solanine. Peels were cooked by baking, frying and baking-frying. The two types of fried peels contained more α-chaconine (2.18–92.82 mg/100g cooked peel) and α-solanine (1.09–72.09 mg/100g cooked peel). Four commercial potato peel products – wedges, slices, fried peels and baked-fried peels – contained 3.60–13.71 mg α-chaconine/100g cooked product and 1.60–10.48 mg α-solanine/100g cooked product.

Development of the frontal bone and cranial meninges in the embryonic chick: An experimental study of tissue interactions

Abstract: The frontal region of the embryonic chick was studied to determine whether epithelial influences are necessary for frontal bone development. The frontal bone is a membrane bone, of neural crest and head mesodermal origin, which develops within mesenchyme sandwiched between two epithelia, neural ectoderm and epidermis. Rudiments were treated enzymatically to separate epithelial and mesenchymal tissues. Frontal mesenchyme then was grown as chorioallantoic membrane grafts either in the presence or absence of neural ectoderm and/or epidermis. The results indicate that neural ectoderm, though required during early stages of development to induce frontal bone development (Schowing, 1968), is not required during later stages (HH 22-30, the stages tested in this study) for osteogenesis. Epidermis, however, was shown to be required for frontal bone development during the stages tested. Frontal mesenchyme formed bone when epidermis was present on the outer aspect of the mesenchyme, and did not form bone when the epidermis had been removed prior to grafting, whether or not neural ectoderm was present. This dependence upon epidermis continues beyond the onset of meningeal differentiation. Once the outer ectomeninx-dermis is distinguishable from the inner endomeninx, osteogenic capabilities are confined to the ectomeninx-dermis layer. Furthermore, the ectomeninx-dermis layer attached to epidermis is able to form membrane bone in the absence of the endomeninx and neural ectoderm. The endomeninx, though normally nonchondrogenic, was shown to be capable of forming cartilage when the neural ectoderm is removed. Neural ectoderm, therefore, may have an inhibitory effect on chondrogenesis in the endomeninx.

Potato top growth as influenced by temperatures

Abstract: A study was conducted to establish a growth rate response of potato plant (Solanum tuberosum L.) tops to exposure to 72-hr periods of six constant temperature treatments (10, 15, 20, 25, 30, 35°C) and to determine a thermal optimum for vegetative potato growth rates. The plants were maintained under “no stress” soil moisture conditions throughout the study. The temperature treatments were accomplished by inserting the plants into a growth chamber for 72 hours at selected temperatures. Maximum growth (as measured by percent change in leaf area) occurred at 25°C with temperature growth differences significant at the 5% level. Plant height measurements (percent change occurring during treatment time) showed maximum stem elongation at 30°C during an early growth stage and 25°C during stage 2 (4 weeks later). Predictive models developed from the data indicate maximum rates of leaf area increase in both growth stages occur at 24.7°C and that maximum rates of stem elongation occur at 31.3 and 27.4°C for growth stages 1 and 2, respectively. Leaf water potential and stomatal resistance measurements taken at the end of each treatment period indicated that no water stress occurred.

The eurythermal myofibrillar protein complex of the mummichog (Fundulus heteroclitus): adaptation to a fluctuating thermal enviroment

Abstract: Mummichogs from salt marshes of the Atlantic coast of Maine (USA) experience a mean seasonal temperature range of −1 °C to +15 °C. However, during summer tidal cycles they may experience rapid temperature changes between 15 °C and 30 °C. Observations of animals in the wild suggest that swimming capability is maintained during acute temperature fluctuations which would substantially impair contractile function in other fishes.

Progeny production by trichogramma minutum (hymenoptera: trichogrammatidae) utilizing eggs of choristoneura fumiferana (lepidoptera: tortricidae) and sitotroga cerealella (lepidoptera: gelechiidae)

Abstract: Can. Ent. 115: 1245-1252 (1983) Mean daily progeny production by Trichogramma minutum ("Maine strain") was 15.2 in Choristoneura fumiferana and 10.9 in Sitotroga cerealella eggs. Total progeny production was higher in 5. cerealella, but not significantly different from that of C. fumiferana eggs. Significantly more eggs were deposited by T. minutum the first day than in subsequent days regardless of host. We found no significant relationship between progeny produced by females and the day of male death as previously reported. Ratio of femalesimales decreased significantly with increasing age and oviposition activity of the mother. The oviposition period spanned 68% of the female's life span when S. cerealella eggs were available; whereas females spent significantly less time (60%) ovipositing in C. fumiferana eggs. Resume

Ploidy of Hybrid Grass Carp X Bighead Carp Determined by Flow Cytometry

Abstract: Flow cytometry was used to identify polyploid fish by means of measuring deoxyribonucleic-acid fluorescence in erythrocytes. One polyploid grass carp Ctenopharyngodon idella and one polyploid bighead carp Hypophthalmichthys (=Aristichthys) nobilis were identified among 38 fish of each species. Ten hybrids identified as diploids on the basis of morphology were confirmed to be diploid. All hybrids identified as polyploid morphologically were indeed polyploid, but two of these were tetraploid rather than triploid. Received May 14, 1982 Accepted February 15, 1983

Pupation site selection inDrosophila simulans

Abstract: Selection for increased pupation height was carried out for 17 generations in two lines ofDrosophila simulans derived from a genetically heterogeneous base population. The realized heritability for mean pupation height in each line, calculated over the 17 generations, did not differ significantly from zero. Both selected lines tended to pupate away from the center of the culture medium to a greater extent than the control in the latter generations of the experiment but not in earlier generations. Pupation height may have been refractory to artificial selection because of an adaptation of this species to pupate on the larval food source. In a subsequent experiment, each line was tested at three larval densities in an apparatus different from the one used for selection. Each successively higher density showed a corresponding increase in pupation height. Both selected lines had higher mean pupation heights than the control line. The differences between lines became more pronounced as the larval density increased.