Movement of walleye in an impounded reach of the Au Sable River,Michigan, USA

Synopsis We estimated long-range spawning and foraging movements of walleye and observed their use of river and reservoir habitats between two large hydroelectric dams on the Au Sable River, Michigan. We used radiotelemetry to monitor seasonal and daily movements of 11 large walleye. Walleye ranged throughout the entire reach between the two dams. Eight of the 11 fish used both river and reservoir locations. Walleye migrated upriver in April or May and presumably spawned near the dam tailwaters. After spawning, walleye remained in the river for up to 6months, usually establishing local ranges. During this time, they occupied low-velocity refuges within the first 25 km of the upstream dam. They seldom occupied the downstream area, which has higher variation around the mean temperature. Food availability and water temperature may have affected the length of time that walleye remained in the river after spawning. All walleye overwintered in the reservoir. We designed this study to evaluate if walleye have a potential negative impact on brown trout, Salmo trutta. In summer, walleye were often present near sites where fingerling trout were stocked. We found the highest potential for interaction between the two species occurs within the first 25km of the upstream dam during summer. The movement patterns of and habitats used by large walleye validate concerns that walleye could compete with adult brown trout for food and resting sites and prey on juvenile brown trout.     

Glycogen and other soluble glucans from chytridiomycete and oomycete species

Dry weight, protein, lipid, and glycogen were determined at various times during cultivation of the Chytridiomycetes, Rhizophydium sphaerotheca and Monoblepharella elongata. M. elongata had relatively stable levels of glycogen, but, in R. sphaerotheca, glycogen levels showed significant changes, particularly in older cultures in which a depletion of glycogen was accompanied by a marked thickening of the cell walls. Glycogen was a significant cellular constitutent in both chytridiomycete species. In R. sphaerotheca and M. elongata, respectively, glycogen accounted for as much as 6% and 8.1% of the dry weight. In purified glycogens of both species, only -1,4-and -1,6-linked glucosyl residues were detected and the absorbance spectra of I₂-complexes were similar to those of other well characterized glycogens. Purified Rhizophydium glycogen had a -amylolysis limit of 43%, and a of approximately 12. For the Monoblepharella polysaccharide, the respective values were 45% and 11. In extracts of the Oomycetes, Pythium debaryanum, Mindeniella spinospora, and Apodachlya sp., only -1,3- and -1,6-linked glucosyl residues were detected. These glucans were not iodophilic nor were they sensitive to -amylase and -amylase. The properties of the oomycete polysaccharides suggested that they were similar to the mycolaminarans of Phytophthora spp. Although both investigated chytridiomycete species produced glycogen with typical properties, glycogen was apparently absent in the investigated Oomycetes.     

Costs and benefits of a cleaning mutualism

Juvenile Atlantic salmon or parr ( Salmo salar L.) maintain station at certain locations in flowing stream water. This position choice is assumed to involve the maximization of energy intake, based upon food availability which is usually directly related to water flow rate. Conversely energy expenditure, including station holding behaviour, foraging and defending preferred sites, is inversely related to water flow rate. Adaptations of parr to life in fast flows implies that station holding is energetically inexpensive at water speeds up to the maximum sustained holding speed, which is fish specific, thus the most important energetic consideration for parr is the ability to maximize food intake. Ten groups of three parr were each observed for 60 min within an artificial stream tank over a heterogeneous substratum. Individual position choice and behaviour were recorded continuously. For each location chosen by the parr the potential upstream line‐of‐sight (LOS), defined as the maximum distance upstream that the water surface would be visible, was calculated. At those sites where foraging behaviour was observed, the mean upstream potential LOS was significantly greater than at sites where other behaviours were observed and at 400 randomly generated sites within the tank. When foraging, parr usually take food from the stream drift and there is a significant time expenditure on food location, identification and catching. Results presented here would seem to confirm that to maximize time available to make these decisions, a fish would be expected to maximize the distance over which it can observe potential food particles.     

Stream position choice in salmon parr: maximisation of foraging efficiency

Juvenile Atlantic salmon or parr (Salmo salar L.) maintain station at certain locations in flowing stream water. This position choice is assumed to involve the maximization of energy intake, based upon food availability which is usually directly related to water flow rate. Conversely energy expenditure, including station holding behaviour, foraging and defending preferred sites, is inversely related to water flow rate. Adaptations of parr to life in fast flows implies that station holding is energetically inexpensive at water speeds up to the maximum sustained holding speed, which is fish specific, thus the most important energetic consideration for parr is the ability to maximize food intake. Ten groups of three parr were each observed for 60 min within an artificial stream tank over a heterogeneous substratum. Individual position choice and behaviour were recorded continuously. For each location chosen by the parr the potential upstream line‐of‐sight (LOS), defined as the maximum distance upstream that the water surface would be visible, was calculated. At those sites where foraging behaviour was observed, the mean upstream potential LOS was significantly greater than at sites where other behaviours were observed and at 400 randomly generated sites within the tank. When foraging, parr usually take food from the stream drift and there is a significant time expenditure on food location, identification and catching. Results presented here would seem to confirm that to maximize time available to make these decisions, a fish would be expected to maximize the distance over which it can observe potential food particles.     

Population changes in sympatric Great and Long-tailed Cormorants (Phalacrocorax carbo and P. africanus): the effects of niche overlap or environmental change?

Between January 1993 and January 1995, the number of Great Cormorants (Phalacrocorax carbo) using Lake Naivasha, Kenya (00° 45 S, 36° 20 E) for foraging and resting increased 56%, while the number of sympatric Long-tailed Cormorants (Phalacrocorax africanus) decreased 64%. In 1995 and 1996, we documented habitat changes and conducted monthly population and resource-use surveys of the two species in an attempt to discover the most likely reasons for these changes. The increase in Great Cormorants was probably the result of immigration from nearby Lake Nakuru due to extreme water level reductions there. Lake Naivasha also experienced falling water levels and transparency during this period, but these changes were not as severe and are not considered likely reasons for the decline in Long-tailed Cormorant numbers. Despite some probable dietary overlap, the two species were well separated in terms of foraging locations, foraging methods, resting habitats and breeding timing. The decline in Long-tailed Cormorant numbers may be connected with increased disturbance by fishermen along the lake littoral, this species' primary feeding location.     

Microtubular structures developed in response to a carbamate herbicide in plant mitosis

Summary Indirect immunodetection of tubulin showed that the herbicide carbetamide activated silent signals left by the preprophase band (PPB) and by old phragmoplasts. Thus, after half an hour of treatment, 5.3% of anaphases inAllium cepa L. meristems showed spindle microtubules pointing to sites of the longitudinal cell membranes which, under control conditions, would only start attracting microtubules from the growing phragmoplast at late telophase. After 2 h, 12.8% of the telophases showed not only the expected phragmoplast between the two sister nuclei, but one or two additional phragmoplasts, at one or both cell tips, the sites of the phragmoplasts from the telophases of previous cycles. A few binucleate cells, obtained by aborting phragmoplast formation by a short caffeine treatment, developed three phragmoplasts in their next mitosis (bimitosis) in the presence of carbetamide: one between each sister pair of telophasic nuclei plus an extra one. The latter also occupied the site of the phragmoplast of the telophase of the previous cycle.Abbreviations PPB preprophase band of microtubules - EGTA ethylene glycol-bis(-amino-ethyl-ether)-N,N,N,N-tetraacetic acid - PMSF phenylmethylsulfonyl-fluoride - PIPES piperazine-N,N-bis(2-ethane sulphonic acid) - PBS phosphate-buffered saline - DAPI 4,6-diamidino-2-phenylindole     

Changes in the spectral absorption of cone visual pigments during the settlement of the goatfish Upeneus tragula: the loss of red sensitivity as a benthic existence begins

The goatfish Upeneus tragula undergoes an abrupt metamorphosis at settlement when the pelagic larvae begin a reef-associated benthic mode of life. A microspectrophotometric investigation of the retinal visual pigments was carried out on fish prior to, during, and following settlement. It was found that the visual pigment in the long wavelength-absorbing member of the double cones in the dorsal retina changed rapidly from a rhodopsin with a wavelength of maximum absorption (max) of 580 nm to that of 530 nm. The second member of the double cones always had a rhodopsin with the max absorbing at shorter wavelengths. Prior to settlement the average for this class of cones was 487 nm whereas during and immediately following the settlement period the max recorded from individual outer segments was found to vary between 480 nm and 520 nm, with two possible classes of cone absorbance emerging within this range. These two classes of absorbance had average max values of 487 and 515 nm. The average max of the paired cone classes in one larger wild-settled fish were found to be at 506 nm and 530 nm. No change was detected in the max of the single cones or the rods which were always found to have a max of about 400 nm and 498 nm respectively. The loss of the redabsorbing pigment occurred over the same time scale as the metamorphosis of morphological features associated with the settlement process. It is thought that the loss of this visual pigment is associated with the change in light environment of the fishes as they leave the surface waters to begin a benthic mode of life in deeper water.Abbreviations AIMS Australian Institute of Marine Science - ANOVA Analysis of variance - IR infra-red - max wavelength of maximum absorption - MSP microspectrophotometer - NA numerical aperture - SL standard length     

Use of mires and food habits of sika deer in the Oze Area,central Japan

Sika deer Cervus nippon entered the Oze Area, a snowy area in central Japan, in the 1990s. The use of mires and the food habits of this species were studied in 1999 and 2000. Deer used the mires immediately after snow melted and did not use the mires in mid summer, although they did use them lightly in autumn. The summer food habits differed from those of the deer population living in Nikko in the lower area: non-Sasa graminoids and other monocotyledonous leaves occupied more (approximately 30%) of the feces in the former population, whereas Sasa nipponica, a dwarf bamboo, was the dominant food (60%) of the latter population. Seasonal changes in fecal composition in the Oze deer were that mire graminoids occupied a considerable portion of their food in spring (11.6%) and summer (17.0%), whereas the amount of dwarf bamboo increased in fall (26.0%). Despite the small size of the mires, Oze deer appear to prefer mires to forests. Nitrogen concentrations of the mire plants did not differ from those of the forest plants; however, foraging efficiency would be greater in the mires and this may explain the preference observed. Despite the small total biomass, leaf biomass of the mire was equivalent to that of the adjacent forest floor. In addition, biomass was concentrated near the ground, or the biomass concentration was greater than that of the forest floor.     

Composition of Endemic Fish Assemblages in Relation to Exotic Species and River Regulation in a Temperate Stream

Spatial variation in the fish community of the regulated Raia stream (Portugal) was examined during the summer of 1995. Variation in the native fish community (abundance of species-size combinations) was explicitly related to both the abundance of exotic species and habitat variables. The fish community changed in space from assemblages characterised by the high relative abundance of Leuciscus pyrenaicus, Leuciscus alburnoides and the smaller size classes of Barbus bocagei (all Iberian endemics with total length, TL, < 100mm to assemblages characterised by the high relative abundance of Chondrostoma polylepis (Iberian endemic) and B. bocagei with TL > 200mm and of exotics Micropterus salmoides and Lepomis gibbosus (> 100mm TL). The former assemblages used shallow sites far from downstream dams with some current whereas the latter assemblages used deeper sites closer to downstream dams without current velocity and with abundant floating macrophytes. Both exotic species and habitat variables were significant correlates of endemic assemblage composition in the Raia stream and the abundance of M. salmoides > 150mm in TL was the best biotic predictor of endemic assemblage composition. The total variation in the community of endemic fish was partitioned into four components: (i) associated uniquely with exotic species - 12.6%, (ii) associated uniquely with habitat variables - 27.6%, (iii) associated both with exotic species and habitat variables - 14.5%, and (iv) that unexplained - 45.3%. A significant association of exotic species with the endemic fish community remained after accounting for the selected environmental variables and a strong (habitat) x (exotic species) interaction was indicated.     

The incorporation and characterization of powdery mildew resistance from Aegilops longissima in common wheat (T. aestivum L.)

Summary In the progeny of a hybrid between monotelosomic line 3B of Chinese Spring wheat and Chinese Spring — Aegilops longissima ditelosomic addition line G a cytologically stable strain was selected consisting of 20 wheat chromosome pairs, one pair of telosomic chromosome 3BL and one pair of telosomic longissima chromosome G. Inoculating Chinese Spring — Aegilops longissima addition and substitution lines with ten different powdery mildew isolates, partial resistance was observed. The infection grade as well as the number of spores/cm² leaf area were significantly reduced.     

Growth ofEucheuma isiforme (C. Agardh) J. Agardh on experimental rafts off the coast of Yucatan State,Mexico

A field experiment was carried out at two sites off Yucatan State, Southeast Mexico, in order to determine the feasibility of culturing the red seaweedEucheuma isiforme; this was done during May–September 1989. At both sites (Uaymitun and Dzilam) the 25 days harvest and 14 algae per line plant density growth rates (2.21% day^–1 and 1.21% day^–1, respectively) were significantly higher (p<0.05) than those obtained with other combinations of the two factors tested (50, 75, 100 and 125 days harvest and 9 and 14 algae per line plant density). The mean carrageenan content of the cultured algae was 35.8% and 31.4% at Uaymitun and Dzilam, respectively.     

Effect of Gamma Irradiation on Embryogenic Avocado Cultures and Somatic Embryo Development

Embryogenic avocado cultures were exposed to ionizing irradiation in order to determine its effect on proliferation and subsequent somatic embryo development. The approximate PD₅₀ as determined by linear regression is 35 Gy 2 weeks after irradiation for Fuerte 2.11.1 and 4 weeks after irradiation for T362 2.11.1. Irradiation of embryogenic cultures did not significantly affect the number of early stage Fuerte 2.11.1 somatic embryos that developed directly from irradiated cultures; however, 10–50 Gy inhibited somatic embryo development. Irradiation of T362 2.11.1 embryogenic cultures at 25–50 Gy inhibited the number of intermediate and mature stages of somatic embryos that developed directly from irradiated cultures, and 50 Gy inhibited somatic embryo maturation. Inhibition of somatic embryo development could be partially offset by proliferation of irradiated embryogenic cultures as suspensions. Irradiation up to 10 Gy significantly increased the number of mature Fuerte 2.11.1 somatic embryos that developed from suspension cultures. Irradiation with doses up to 25 Gy stimulated development of heart stage T362 2.11.1 somatic embryos; however, mature somatic embryo development was suppressed at dosages of 10 Gy and greater.     

Effects of drought on the yellowing status and the dynamics of mineral elements in the xylem sap of declining spruce (Picea abies L.)

In order to test the effects of drought on the occurrence of spruce yellowing, in the Vosges Mountains (northeastern France), the soil of a plot of a 30-year-old spruce stand was protected from throughfall input by a roof for two months during the summer. The degree of yellowing of the trees from the dry and control plots was measured before and after the experiment. Sap flow and sap concentrations were measured in the control plot during the whole of the growing season, and in the dry plot during the drought period. Drought brought about an increase of needle yellowing linked to a reduction in Mg uptake. A decrease in sap concentration of concentration of Ca, Mg and K occurred in the dry plot as compared with the control plot at the end of the drought period. It is concluded that climatic stress could have been the triggering factor of spruce yellowing in the Vosges during the eighties.     

Why do Foraging Stream Salmonids Move During Summer?

We hypothesize that foraging stream salmonids move during summer because (1) they monitor habitat conditions at a reach scale (100s of m), and (2) dominant fish move when conditions in their present foraging location become sub-optimal relative to conditions at other locations in the reach. To test these ideas, we quantified temporal variation in foraging habitat quality between late spring and early fall in a reach of a small Rocky Mountain brook charr, Salvelinus fontinalis, stream, predicted optimal-foraging fish distributions within the reach, and experimentally manipulated access to foraging sites and measured fish responses. Our results show that high-quality foraging sites were located at certain places in the reach during one period, but at different places during others, consistent with the hypothesis that fish movement is required if dominant fish are to occupy high-quality foraging sites throughout summer. The optimal foraging model was able to predict foraging locations within study pools, but not the exact location of individual fish within the pools or the reach. However, empirical evidence suggests that fish were distributed in order to maximize energy intake at the reach scale. Finally, dominant fish excluded from their preferred foraging location either left the pools (three of six cases), or began to occupy focal points of the next largest fish which, in turn, exited the pool (two of six cases). If habitat selection was occurring only within habitat units, then large fish, when excluded from their preferred locations, would select the next best locations within the pool. Taken together, these results suggest that charr use summertime movements to both monitor habitat conditions at a large spatial scale, and to gain access to optimal foraging locations even as conditions change temporally.     

Two-dimensional 1H NMR study of two cyclobutane type photodimers of thymidylyl-(3′→5′)-thymidine

2D NMR spectroscopy and J coupling constant analysis are applied to resolve the structure of two photoproducts of thymidylyl-(35)-thymidine. These products are cyclobutane type thymine dimers possessing the cis-syn (the predominant one) and trans-syn geometry. The cis-syn is formed in an ANTI-ANTI conformation about the N-glycosyl linkages and resembles the normal base-stacked configuration. The glycosidic conformation in solution of the 5 terminal fragment differs from the crystal in which the less common SYN conformation is observed. In this isomer only the sugar pucker of the 3 terminal fragment is changed substantially with respect to the dinucleotide. The trans-syn isomer is formed in a SYN-ANTI glycosidic conformation. In this isomer the sugar puckers of both deoxyribose rings are affected and a preference for a pure 2-endo conformation is observed.Abbreviations dTpdT 2-deoxythymidylyl-(35)-2-deoxythymidine - dTp[]dT cyclobutane type photodimers of dTpdT - dTp- and dTp[]- their 5' terminal fragments (fragment A) - -pdT and-[]pdT their 3 terminal fragments (fragment B) - RP-HPLC reversed-phase high-performance liquid chromatography - COSY two-dimensional correlated spectroscopy - 2D NOE two-dimensional nuclear Overhauser spectroscopy     

Genetic transformation in two potato cultivars with T-DNA from disarmed Agrobacterium

Summary Derivatives of potato (Solanum tuberosum cv.'s Maris Bard and Desiree) transformed with disarmed T-DNA from genetically engineered Agrobacterium tumefaciens strains were isolated. The transformed plants were recovered from shoot-forming tumours induced by infection of wounds with mixedcultures of shoot-inducing A. tumefaciens strains T37 and either Agrobacterium strain LBA1834(pRAL1834), (Hille et al. 1983) or LBA4404(pBIN6; pRAL4404), (Bevan 1984). Two small-scale feasibility experiments gave at least four Maris Bard plants transformed with pRAL1834 T-DNA and two Desiree plants with pBIN6 T-DNA. The transformed Maris Bard plants were morphologically abnormal and highly aneuploid. This was probably an unfortunate side-effect of a tissue culture-step introduced to promote the efficiency of shoot regeneration. The transformed Desiree plants, in contrast, were isolated without promoting additional shoot-growth. They were morphologically normal, contained 47 and the euploid 48 chromosomes per cell respectively and had improved growth on media containing kanamycin.     

Reduction of Reactive Distance and Foraging Success in Smallmouth Bass, Micropterus dolomieu, Exposed to Elevated Turbidity Levels

We determined how turbidity affected the reactive distance and foraging success of smallmouth bass, Micropterus dolomieu. Smallmouth bass reactive distance decreased exponentially with increasing turbidity, from 65cm in clear water to 10cm at the highest turbidity. Turbidity significantly decreased the probability of a fish reacting to a prey item, but did not influence foraging success following reaction to the prey. Elevated turbidity may reduce stream fish foraging efficiency and decrease prey consumption.     

Ganglioside lactones:1H-NMR determination of the inner ester position of GD1b-ganglioside lactone naturally occurring in human brain or produced by chemical synthesis

The complete definition of the chemical structure of G_D1b-ganglioside (G_D1b) lactone isolated from human brain has been given by means of spectrometric and spectroscopic analyses. G_D1h lactone contains a single ester linkage involving the external sialic acid carboxyl group and the C-9 hydroxyl group of the internal sialic acid unit. A synthetic lactone of G_D1b prepared treating G_D1b with glacial acetic acid characterized in the same way showed an identical chemical structure.Abbreviations: Ganglioside nomenclature is according to Svennerholm [16] and the IUPAC-IUB Recommendations [17] G_M1 G_M1-ganglioside, II³NeuAc-GgOse₄Cer, Gal1-3GalNac1-4[NeuAc2-3]Gal1-4Glc1-1Cer - G_D1b G_D1b-ganglioside, II³(NeuAc)₂GgOse₄Cer, Gal1-3GalNAc1-4[NeuAc2-8NeuAc2-3]Gal1-4Glc1-1Cer - G_D1b lactone G_D1b-L, Gal1-3GalNAc1-4[NeuAc(1-9)2-8NeuAc2-3]Gal1-4Glc1-1Cer - Cer ceramide - FAB-MS fast atom bombardment-mass spectrometry - ¹H-NMR proteon nuclear magnetic resonance - 1D-NMR one dimensional NMR - 2D-COSY two dimensional correlated spectroscopy - DMSO-d₆ deuterated dimethylsulfoxide     

Plant regeneration from grape callus stored under a combination of low temperature and silicone treatment

Effects of the combination of low temperature and silicone treatment on the storage of grape callus (Vitis vinifera L. x V. labrusca L. cv. Kyoho; V. vinifera L. cv. Koshusanjaku) were examined. In Kyoho, the calli were stored at 10°C successfully for up to 360 days. Embryogenic calli of Koshusanjaku stored at 10°C retained the ability of embryogenesis after 360 days of storage. However, the color of both calli became brownish. This was improved by the combination of low temperature and silicone treatment. The calli of Kyoho survived by the storage under the combination of 15°C and silicone. Embryogenic calli stored at 10 and 15°C in combination with silicone survived for 360 days, and regenerated only after transfer onto a regeneration medium. Thus the combination of low temperature and silicone affects the longevity of the grape callus.     

Characterizing bisexual Artemia populations by isoelectric focusing

Isoelectric focusing (IEF) of protein extracts, -Esterase and Phosphoglucose isomerase, from groups of Artemia adults from different bisexual populations were studied. Both gave clear separation between the Old and New World species. The second was more polymorphic, allowing a discrimination among Mediterranean populations.