GENETIC AND CONCHOLOGICAL COMPARISON OF SNAILS (HELIX ASPERSA) DIFFERING IN SHELL DEPOSITION OF LEAD

Populations of snails inhabiting areas with different historiesof Pb contamination differed in their deposition of Pb in shellrelative to soft tissues. Genetic variation, measured usingisozymes, was not related to Pb history nor geographic distancebetween populations. Shell characteristics were significantlydifferent among sites; shell dry weight was strongly relatedto soil calcium levels. Shells of snails from areas with longhistories of Pb contamination were significantly more robust(greater shell width/shell height ratio) than snails from otherlocations. H. asprsa adaptation to Pb contamination may involvesignificant changes in shell characteristics but these do notcorrelate with genetic traits assessed with allozymes (Received 29 December 1994; accepted 15 October 1995)     

DISTRIBUTION AND ABUNDANCE OF HYDROBIA ULVAE (PENNANT) IN THE LOWER MEDWAY ESTUARY, KENT

Measurements of densities and distribution of populations ofH. ulvae were made in the lower Medway estuaryduring the period1969–1975, together with measurements of salinity, substrateparticle size and macrophyte distribution. Results indicatedthat sheltered siteswere more favourable to the snail as shownby higher population density and greater shell size. ^*Current address: Southern Water Authority, Maidstone, Kent (Received 20 May 1979;     

INTRA-POPULATION VARIATION OF THE SHELL OF LITTORINA RUDIS (MATON) (MOLLUSCA: PROSOBRANCHIA)

Shell variation within a single population of Litlorina rudis(Maton), collected near the Biological Station at Trondheim,Norway, was studied. The variation of the shell features studied, which includedthe shape of the basal part of the outer lip, and the relativeheight of the spire, width of the shell and of the aperture,were found to be at least partially related to shell height.Furthermore, the shell shape in the population investigated,besides varying with age, also varies due to shell damage. Nosignificant differences were found between the shapes of theshells of males and females. The shell characteristics of different populations of L. rudisalso vary greatly, one of the causes being differences in theenvironmental conditions. When studying this variation betweendifferent populations, however, it must be emphasized that onlyundamaged shells of individuals of about the same age shouldbe compared, in order to obviate the effects of the variabilitydue to age differences and shell damage within each individualpopulation. ^*Contribution from Trondhjem Biological Station no. 199 (Received 18 February 1980;     

EFFECTS OF WOUND HEALING ON ZINC DISTRIBUTION AND ALKALINE PHOSPHATASE ACTIVITY OF HELIX ASPERSA (GASTROPODA: PULMONATA)

Helix aspersa were loaded with ⁶⁵zinc and after 2 and 5 daysstarvation there was no significant reduction in the zinc concentrationof the digestive gland and shell. Wounding of the optic tentacle,foot tissue and partial shell removal of H. aspersa resultedin deposition of ⁶⁵zinc in the wound area. Alkaline phosphataseshowed no increase in concentration at the sites of wounding. (Received 15 October 1985;     

Temperature-related diversity of shell colour in the intertidal gastropod Batillaria

The intertidal snail Batillaria exhibits remarkable variationin the shell colour within and among populations. Field studywas conducted to determine the factors in maintaining observedshell colour polymorphism. Geographical variations in shellcolour polymorphisms in B. attramentaria were significantlycorrelated with the temperature of the locality of the population.Darker morphs were predominant in colder regions, whereas lightermorphs increase their proportion in warmer regions. A consistentassociation was also found in B. multiformis that co-existedwith B. attramentaria. Strong predatory pressure imposed bydigenean trematode parasites was observed in B. attramentaria.However, it is unlikely to affect the colour variations, becauseno correlation exists between colour morphs and trematode parasitism.Although visual selection may also contribute to colour variationin Batillaria, no evidence is found for the existence of visualpredators that affect colour patterns of these snails. The deficitof variation in cold regions is possibly due to selection againstbrighter morphs, because bright colours reflect heat. Althoughdark shells absorb sunlight and may therefore be exposed tothe risks of overheating and drying up in a hot habitat, thedarkest morph was frequently observed in the warmer regions,suggesting that physical selection on the colour morphs canbe relaxed in the warmer environment. Our results suggest thatclimatic selection is one of the significant factors maintainingshell colour polymorphism in these intertidal snails. (Received 13 December 2006; accepted 14 April 2007)     

GROWTH AND REPRODUCTION OF THE MINUTE LAND SNAIL PUNCTUM PYGMAEUM (DRAPARNAUD)

Reproductive characters and growth of Punctum pygmaeum wereinvestigated under laboratory conditions. Eggs were laid singlyat intervals of 2–8 days. Egg size averaged 0.41 by 0.50mm. Due to a variable period of egg retention, newly depositedeggs contained differently developed embryos resulting in anincubation period varying from 1 to 34 days. Each snail on averagelaid 6.0 eggs (range 1–16 eggs) during its life. Egg productionrate and hatching success in individuals kept in isolation werethe same as in individuals kept in pairs. Hatchlings measured0.49 mm in shell breadth. Snails grew throughout their life,but the growth rate declined significantly at a shell breadthof 1.3–1.4 mm, the point at which the onset of sexualmaturity occurred. Comparison of reproductive characters ofsnails living in leaf litter revealed that very small-sizedspecies produce few, but in relation to their shell size largeeggs, which they oviposit singly. ^*Present address: Zoological Institute, University of Basel,Rhein-sprung 9. CH-4051 Basel, Switzertand (Received 23 May 1988; accepted 11 July 1988)     

PREDATION ON THE BIVALVE CHOROMYTILUS MERIDIONALIS (KR.) BY THE GASTROPOD NATICA (TECTONATICA) TECTA ANTON

The effects of a population of the boring gastropod Natica tectaon the bivalve Choromytilus meridionalis were investigated atBailey's Cottage, False Bay, South Africa. In July 1979 theN. tecta density on the mussel bed averaged 69 m^–2 andthe population consisted mainly of reproductively mature individualsbetween 20–33 mm shell width. Laboratory experiments on N. tecta showed that prey size selectionis an increasing function of predator size. The prey size rangetaken by large N. tecta is also greater than that taken by smallindividuals. The position of the borehole on the mussel shellis a function of the way in which the shell is held by the footduring the boring process. Consumption rates measured in thelaboratory showed an increase from approximately 1 kJ per weekin 18 mm N. tecta to 4.5 kJ per week in 28 mm individuals. Populationconsumption in the field was calculated as 663 kJ m^–2month^–1. It was estimated that at this rate the standingcrop of mussels in the pool would be eliminated within 10 months.Field measurements showed significant depletion after 6 months. New spat settlement of mussels occur every 4–6 years.The growth curve shows that after one year the population meansize exceeds 30 mm shell length, which is beyond the prey selectionsize range of small N. tecta. It was concluded that at the timeof a new mussel settlement a niche is provided for the simultaneoussettlement and growth of juvenile N. tecta in high densities.However, within one year the increase in prey size, togetherwith depletion due to over-exploitation, limits population growthand density in N. tecta. (Received 14 March 1980;     

SHELL STRENGTH OF COLOUR MORPHS OF THE MANGROVE SNAIL LITTORARIA PALLESCENS

The load required to break shells of the snail Littor-aria pallescens(Philippi) (Gastropoda: Littorinidae) has been established.Mass increases more than proportionally with size. Size forsize, relatively heavy shells are thicker than relatively lightones, and the thicker shells are stronger. Three samples fromdifferent localities differ significantly in strength. Littorariapallescens is polymorphic for shell colour. It is shown thatin two of the three samples, both from Papua New Guinea, individualsof the dark morph are significantly heavier and stronger thanthose of the yellow morph, while there is no difference betweenmorphs in the third sample, from Thailand. In the sample withthe most robust shells the dark individuals are stronger, massfor mass, than yellows. Thus, colour morph is sometimes, butnot always, associated with differences in shell characteristicswhich are likely to affect fitness. Where there is a difference,the dark morph is estimated to be on average about 22% strongerthan the yellow morph. The difference between morphs is smallcompared with the large variation in shell characters associatedwith size. (Received 20 May 1992; accepted 22 June 1992)     

Free Cellular Riboflavin is Involved in Phase Shifting by Light of the Circadian Clock in Neurospora crassa

Phase shifting by light of the circadian conidiation rhythmof the Neurospora crassa strain band, of the riboflavin-deficientdouble mutant band rib2 and of the temperature-sensitive doublemutant band ribl was measured. Fluence response curves of theband strain exhibited two distinct steps, whereas those of bandribl and band rib2 revealed only one step. Maximum phase advancesobserved were 5.5 h in band and 10.4 h in the band rib strains.Sensitivity of band rib2 to light was proportional to the riboflavinconcentration in the growth medium over a 100 fold range. Extracellularflavin in the medium did not sensitize the strains. Riboflavinapplied after exposure to light showed no effect. Light sensitivitycorrelated with the level of cellular riboflavin. Four analogsof riboflavin, none of which can be phosphorylated, increasedthe sensitivity of Neurospora to light. Even at high riboflavinconcentrations in the medium, the sensitivity of the band rib2strain to light was not saturated. In addition, four riboflavinderivatives with bulky substituents at positions 3, 8 or 10of the isoalloxazine nucleus sensitized both strains. From ourdata, we conclude, that a) a cellular flavin controls the sensitivityof Neurospora crassa to light; b) that this flavin compoundis riboflavin; and c) that the active riboflavin is not proteinbound. ⁴Present address: Teikoku Women's University, Department ofHome Economics, 6-173 Touda-cho, Moriguchi-shi, Osaka, 570 Japan. (Received November 27, 1987; Accepted March 15, 1989)     

Is the midsummer decline of Daphnia really induced by age-0 fish predation? Comparison of fish consumption and MDaphnia mortality and life history parameters in a biomanipulated reservoir

We analysed the temporal pattern of a Daphnia galeata populationand the development of the age-0 Ash community in a long-termbiomanipulated lake (Bautzen reservoir, Germany) during springand early summer of two successive years. In Bautzen reservoir,the age-0 Rsh-Daphnia interaction is a key process within thefood web due to the low abundance of adult zooplanktivorousfish. Daily consumption of daphnids by age-0 fish, as estimatedby a bioenergetics model, was compared to daily mortality ratesof daphnids. In addition, we estimated life history parametersof Daphnia that may indicate predation impact by fish. A midsummerdecline of daphnids occurred only in July of 1996, whereas in1995 the Daphnia biomass remained >4 mg wet weight 1^–1for the entire summer. The percentage of total Daphnia mortalitydue to fish predation before the onset of the midsummer declinewas –2% day^–1. Temporal patterns of individual size,clutch size and size at maturity also indicated that the 1996midsummer decline of daphnids was not the exclusive consequenceof age-0 fish predation. Instead, low reproductive capacityof daphnids also contributed significantly to the decline. Consequently,year-to-year variation of the Daphnia dynamics may be determinedby a fine-tuned ‘timing’ between the period of reducedfecundity and the time of the strongest predation impact byage-0 fish.     

ORGANIC CARBON, ENVIRONMENTAL FACTORS AND GROWTH IN THE SMALL EURYHALINE GASTROPOD, POTAMOPYRGUS JENKINSI (SMITH)

A method of analysing small invertebrates for organic carbon(in the range 6.0 to 1000 µg) is described. The relationshipsbetween organic carbon content, total dry weight and shell lengthwere detemined for Potamopyrgus jenkinsi living in differentcombinations of salinity and temperature. Differences in organiccarbon content were found in relation to weight at differentgrowth temperatures. This work is a further confirmation ofthe usefulness of organic carbon content as a measure of thegrowth or biomass of small invertebrates. ^*Present Address: School of Biology, University College, P.M.B.5323, Port Harcourt, Nigeria. (Received 27 April 1977;     

Estimating chlorophyll a abundance from the 'phytoplankton colour' recorded by the Continuous Plankton Recorder survey: validation with simultaneous fluorometry

The green colour (measured with reference to standard colourcharts) of sections of the Continuous Plankton Recorder (CPR)filtering silk was compared with estimates of chlorophyll aconcentration derived from a fluorometer mounted on the CPRduring seven tows in the North Sea between February and May1991. After the green colour was assessed, the abundance ofphytoplankton cells on the filtering silks was quantified bymicroscope analysis. Data were collected for 115 10-nautical-milesamples over a total of seven cruises. For these 115 samples,there was only a weak (F_1.113 = 3.8, P = 0.05, r² = 0.03) positiverelationship between the colour of the filtering silk and thechlorophyll a concentration. However, when this comparison wasrestricted to four tows (68 10-nautical-mile samples) wherethe recorded phytoplankton cell abundance on the silks was verylow, there was a highly significant (F_1.66 /,69.1, P < 0.001,r² = 0.51) positive relationship between the silk colour andthe chlorophyll a concentration. By measuring the relative colourintensity of CPR standard colour categories and quantifyingthe individual variation in the assessment of colour, a theoreticalmodel was developed which pedicted that if the silks were colouredin direct proportion to the chlorophyll a concentration in thewater, then the expert r² for the relationship between silkcolour and chlorophyll a concentration would be 0.62. The greencolour recorded by the CPR survey was therefore identified asa quantitative index of chlorophyll a concentration, but onlywhen numbers of phytoplankton cells on the CPR silks are nothigh.     

Tritium labelling of amino sugars at C-2 by alkaline epimerization in tritiated water

N-Acetyl-D-[2-³H]glucosamine was synthesized from N-acetyl-D-mannosamineby alkaline 2-epimerization in pyridine containing ³H₂O andnickelous acetate. The reaction involves reversible formationof an enol intermediate and therefore also resulted in incorporationof tritium into N-acetylmannosamine. After completed reaction,the two N-acetylhexosamines were separated from other radioactiveproducts and Morgan-Elson chromogens by chromatography on acolumn of Sephadex G-10, which was eluted with 10% ethanol,and were then separated from each other by chromatography onSephadex G-15 in 0·27 M sodium borate (pH 7·8).The location of the incorporated tritium was established bytreatment of the N-acetylhexosamines with borate under the conditionsof the Morgan-Elson reaction, which converts the sugars to Kuhn'schromogen I with concomitant loss of the C-2 hydrogen. As expected,this treatment resulted in the formation of ³H₂O, indicatingthat the tritium was located at C-2. [2-³H]Glucosamine was preparedby acid hydrolysis of the labelled N-acetylglucosamine and wasconverted to [2-³H]glucosamine 6-phosphate by incubation withhexokinase and ATP. The sugar phosphate was used as a substratefor glucosamine 6-phosphate deaminase (isomerase, EC 5.3.1.10 [EC] )in a simple ³H₂O release assay. N-acetyl[2-³H]glucosamine N-acetyl[2-³H]mannosamine [2-³H]glucosamine glucosamine 6-phosphate deaminase [2-³H]mannosamine     

RADULAR TEETH OF INDO-PACIFIC MOLLUSCIVOROUS SPECIES OF CONUS: A COMPARATIVE ANALYSIS

Species determination in the gastropod genus Conus, heretoforeexclusively based on shell morphology and color pattern, hasled to considerable uncertainty and disagreement. We proposethat qualitative and quantitative radular tooth characters arepotentially useful in differentiating species as well as geographicsubspecies and will improve the taxonomic base. Molluscivorousspecies of Conus, sometimes placed in the subgenera Cylinder, Textilia,Darioconus, and the nominal subgenus, are taxonomically amongthe most difficult. We thus examined intra- and interspecificvariation in radular morphology of 11 of these species, C. ammiralis,C. araneosus, C. bandanus, C. canonicus, C. episcopatus, C. marmoreus,C. nodulosus, C. omaria, C. pennaceus, C. textile, and C. victoriae,and intra- and interregional variations in radular morphologyof C. pennaceus from three geographic regions. Taxonomicallyuseful qualitative characters include presence/absence of one ortwo barbs and a blade, and whether the row of denticles comprisingthe serration is continuous or interrupted. Useful metric charactersinclude the ratios of first barb, second barb, blade, serration,shaft width and base width to tooth length, the ratio of toothlength to shell length, the ratio of shaft width to base width,and the degree of curvature of the teeth. Univariate analysisof variance (ANOVA and unplanned pairwise comparison tests)distinguished 53 of the 55 possible species pairs from eachother by at least one character. Multivariate analysis of variance (MANOVA)indicated statistically significant differences between thespecies in the other two pairs. In C. pennaceus, ANOVA and unplannedpairwise tests differentiated Hawaiian from Indian Ocean samples,and MANOVA differentiated those from Maldives and Sumatra. Thediscrete radular characters sort the 11 species into three groups,and these are consistent with the distribution patterns of thequantitative characters. Radular tooth characters are thus potentiallyuseful in differentiating species and subspecies and shouldbe combined with other character sets in generating future phylogenetichypotheses. ¹ Present address: Department of Pathobiology, University of Pennsylvania,019104-6068, USA ² Author for correspondence: e-mail: kohn{at}washington.edu (Received 23 October 1999; accepted 25 January 1999)     

Developmental Anatomy of the Leaf of L. Ficus religiosa

The leaves of Ficus religiosa show a more or less sigmoid growthpattern, and under the conditions prevailing in Delhi each leafincreases in size in 9 days from about 425 to 4025 mm²(as judgedby the average mature leaf size) after its emergence from thespathe. The leaf is hypostomatic and has paracytic and anomocyticstomata between polygonal epidermal cells. The frequency ofstomata per mm² increases from 33.3 to 400 and the number oflower epidermal cells decreases from about 11 300 to about 3040per mm² with the growth of the leaves while the number of upperepidermal cells decreases from 5600 to 1110. The vasculaturecomprises a single main vein (the mid rib), secondaries, tertiaries,quaternaries, and intermediaries. The number of areoles permm² decreases from 15.5 to 2.7 while the numbers of vein endingsand vein tips per areole show no correlation either with oneanother or with leaf size.     

Soya Bean Seed Growth and Maturation In vitro without Pods

Immature Glycine max (L.) Merrill seeds, initially between 50and 450 mg f. wt, were grown and matured successfully in vitro.Excised seeds were floated in a liquid medium containing 5 percent sucrose, minerals and glutamine in flasks incubated at25 °C under 300 to 350 µE m^–2 s^–1 fluorescentlight. During 16 to 21 d in culture, seeds grew to a matured. wt of 100 to 600 mg per seed at an average rate of 5 to 25mg d. wt per seed d^–1 depending on initial size. Growthrates were maximal during the first 8 to 10 d in vitro but declinedwith loss of green colour in the cotyledons. Seed coats rupturedwith rapid cotyledon expansion during the first 2 d in culture.Embryos were tolerant to desiccation and 80 to 90 per cent germinatedif removed from culture before complete loss of green colour.The growth of excised seeds in vitro exceeded the growth ofseeds in detached pods, but when windows were cut in pods topermit direct exposure of seeds to the medium, seed growth wascomparable. Glycine max (L.) Merrill, soya bean, seed culture, seed growth, seed maturation, germination     

A New Genus and Species of the Family Anulidentaliidae (Scaphopoda: Dentaliida) and its Systematic Implications

Shell, radula, and anatomy of Epirhabdoides ivanovi new genusand species are described from a sample of the Russian VitjazExpedition from the Japan Trench. It is distinguished from thesimilar Laevidentalium sominium by shell morphometrics and radulamorphology. The radula is almost identical with that of Anulidentaliumbambusa (Anulidentaliidae). The anatomy of the mantle margins,however, including dorsolateral slits at the anterior mantlemargin and a connective tissue bolster at the posterior mantleopening is that of the family Rhabdidae. In a parsimony analysisEpirhabdoides ivanovi takes an intermediate position betweena basal grade of Gadilinidae and the remaining Dentaliida implyingconvergent evolution of mantle characters. An alternative butless parsimonious tree with E. ivanovi as sister taxon to Rhabdusrequires convergences in radula characters. This is the firstdocumented case of convergent anatomical features among Scaphopodaand enhances the need of radula and soft part investigationof the conchologically little informative, smooth-shelled dentaliidgroups. (Received 16 March 1998; accepted 1 June 1998)     

SEXUAL DIMORPHISM OF SHELL SHAPE AND GROWTH OF VILLOSA VILLOSA (WRIGHT) AND ELLIPTIO ICTERINA (CONRAD) (BIVALVIA: UNIONIDAE)

Shell shape and growth of two unionacean species, Villosa villosaand Elliptio icterina, are analyzed with univariate and multivariatetechniques. The relationship of shape variables to size variablesis examined. Under the lognormal assumption, parametric testsof these allometric relationships are valid. Variables describingthe ventro-posterior region of the shell are shown to be thebest of those tested for discriminating between the sexes ofboth species regardless of statistical method. Neither speciesexhibits size sexual dimorphism. Shape sexual dimorphism ofV. villosa is constant during adult growth, but the more subtledimorphism of E. icterina changes as adults continue to grow. (Received 20 January 1986;     

Anthocyanins in Modern Roses: Chemical and Colorimetric Features in Relation to the Colour Range

With respect to intravarietal variability, the petals of 15rose (Rosa x hybrida) varieties, representative of the colourrange expressed by modern roses primarily pigmented with anthocyanins,were investigated from chemical and. colorimetric viewpoints.Depending on the variety, the observed colour variations werebased on a more or less complex mixture of cyanidin 3,5-diglucoside,pelargonidin 3,5-diglucoside, quercetin and kaempferol glycosides.The total anthocyanin content ranged from 4 to 109 mg g^–1petal dry wt., while the total amount of flavonol glycosideswas never less than 8 mg g^–1 and could reach 136 mg g^–1petal dry wt. Between cultivars, the pH of the petal outer epidermisvaried from 3·6 to 5·4 units. Using a spectrocolorimeter,the petal colour of each variety was measured. In order to allowquantitative comparisons of colours, the reflectance curveswere further translated into indices calculated using the CIELabsystem. In the aggregate, there were good correlations betweenchemical parameters and colorimetric indices that are lightness(L^*), chroma (C^*) and hue angle (h). Both of these criteria(chemical and colorimetric) appeared sufficient to explain thevisual sense of the petal colour. Key words: Rose, colour, flavonoid, colorimetry, CIELab system     

Paleobiological implications of shell repair in recent marine gastropods from the northern Gulf of California

Shell repair frequencies in eleven species of Recent gastropods from the northern Gulf of California vary with habitat, shell morphology and intensity of durophagous predation. Squat shells with large apertures tend to have high repair frequencies (0.25–0.50). Shell thickness at the aperture and shell size are not correlated with frequency of repair. Significant intraspecific variation in repair frequency exists between habitats. Samples from rocky habitats have statistically higher repair frequencies than samples of the same species from sandy habitats. However, habitat‐related variation between species is not apparent.

Trends in co‐evolution of gastropods and their durophagous predators are based on the indirect evidence of shell repair frequencies through time. Variation in repair frequency due to environmental and morphological factors may obscure predator‐related temporal trends in repair frequency.