A water channel of the nematode C.elegans and its implications for channel selectivity of MIP proteins

A genome project focusingon the nematode Caenorhabditis elegans has demonstrated thepresence of eight cDNAs belonging to the major intrinsic proteinsuperfamily. We functionally characterized one of these cDNAs namedC01G6.1. Injection of C01G6.1 cRNA increased the osmotic waterpermeability (P_f) of Xenopusoocytes 11-fold and the urea permeability 4.5-fold but failed toincrease the glycerol permeability. It has been speculated that the MIPfamily may be separated into two large subfamilies based on thepresence or absence of two segments of extra amino acid residues (~15amino acids) at the second and third extracellular loops. BecauseC01G6.1 (designated AQP-CE1), AQP3, and glycerol facilitator (GlpF) all have these two segments, we replaced the segments of AQP-CE1 with thoseof AQP3 and GlpF to identify their roles. The functional characteristics of these mutants were principally similar to that ofwild-type AQP-CE1, although the values of P_f andurea permeability were decreased by 39-74% and 28-65%,respectively. These results suggest that the two segments of extraamino acid residues may not contribute to channel selectivity orformation of the route for small solutes.

     

Growth and phosphorus uptake of summer phytoplankton in Lake Erken (Sweden)

The thermal stratification in Lake Erken was short and relativelyunstable in 1989. Changes in the species composition of thephytoplankton between early May and August followed the generalsuccession pattern outlined for other temperate lakes. Fast-growing,r-strategist cryptophytes, dominant in the early phase of succession,could be separated sufficiently by 12 µm membrane filtersfrom larger K-strategists like Ceratium hirundinella and Gloeotrichiaechinulata which dominated in July. Under more turbulent conditions,the biomass of diatoms increased, and these species were also>12 µm. Growth rates of the phytoplankton and thoseof the two size groups were sensitive to the species composition,but fitted reasonably to the Droop model. Long turnover timesof orthophosphate in the water, the Phosphorus Deficiency Indicatordefined here as the ratio of the light-saturated rate of photosynthesisand the conductivity coefficient of phosphate uptake, and relativegrowth rates generally indicated low P-deficiency. Moderatedeficiency was observed in late July, towards the end of thestratification period. Steady-state net P-uptake rates werecalculated from the Droop model and compared with instantaneousnet P-uptake rates estimated from ³²P uptake kinetics by thelinear force-flow relationship of Falkner et al. (Arch. Microbiol.,152, 353–361, 1989). The two data sets showed surprisinglysimilar seasonal trends. Depletion of epilimnetic soluble reactivephosphorus (SRP) resulted in enhanced utilization of intracellularlystored P. Such periods were, however, interrupted by elevatedSRP inputs to the epilimnion that led to luxury P uptake anda low incidence of P deficiency.     

In situ Effects of Elevated Atmospheric CO2on Leaf Freezing Resistance and Carbohydrates in a Native Temperate Grassland

The objectives of this study were to quantify changes in leaffreezing resistance and carbohydrate concentrations caused bylong-term (6 years) exposure to elevated CO₂(ambient: 360 µll^-1, elevated: 600 µl l^-1) in five dominant plant speciesgrowing in situ in a native temperate grassland. Across allfive species tested from three functional groups, the mean temperatureat which all leaves were damaged (T₁₀₀) significantly (P = 0.016)increased from -9.6 to -8.5 °C under elevated CO₂ , anda similar marginally significant (P = 0.079) reduction was observedfor the mean temperature that caused 50% leaf damage (T₅₀),from -6.7 to -6.0 °C. The mean temperature at which initialleaf damage was observed (T₀) was not significantly influencedby elevated CO₂ . Although concentrations of soluble sugars(+25%,P = 0.042), starch (+53%, P < 0.001), and total non-structuralcarbohydrates (TNC, +40%, P < 0.001) were significantly higherunder elevated CO₂ , leaf freezing resistance actually decreasedunder elevated CO₂ . Concentrations of soluble sugars were positivelycorrelated with freezing resistance when viewed across all fivecommunity dominants, but within any individual species, no suchrelationships were found. We also found no evidence for ouroriginal hypothesis that increased concentrations of solublesugars increase freezing resistance. Thus, future atmosphericCO₂levels may instead increase the risk of late spring freezingdamage. Furthermore, the strong differences in freezing resistanceobserved among the species, along with decreased freezing resistance,may increase the risk of losing species that have inherentlyweak freezing resistances from the plant community. Copyright2001 Annals of Botany Company CO₂enrichment, frost hardiness, sugar, starch, total non-structural carbohydrates (TNC)     

Sugars in Natural and Artificial Pollen Germination Substrates

The stigmatic exudates and pollen grains of five unrelated specieswere tested for sugars. Glucose, fructose, and sucrose werefound in the stigmatic fluid of Yucca aloifolia L. and glucoseand fructose in that of Oenothera adrummondii Hook. In in vitroexperiments with Y. aloifolia pollen, high germination percentageswere obtained in artificial media containing glucose or sucrose.Fructose, which is present in the stigmatic fluid of the Yuccasp. resulted in high in vitro pollen germination only when borateand calcium were added to the medium. Presence of bound sugarsis indicated in the stigmatic secretion of Citrus aurantiumL. and pollen of the single plant tested germinated at a lowpercentage in artificial sugar media. No sugars were detectedin the stigmatic fluids of Hemerocallis fulva L. and Zea maysL. and in these two species in vitro pollen germination in sugarymedia was negligible or absent. The pollen grains of all five species contain sucrose and thoseof Oenothera and Citrus also reducing sugars.     

DREPANOTREMA NORDESTENSE (LUCENA, 1953) (PULMONATA: PLANORBIDAE): A NEW RECORD FOR THE BOLIVIAN ALTIPLANO AND ITS DIFFERENTIATION BY MORPHOLOGY AND ENZYMES

In 1995, a small planorbid snail new for the Northern Bolivian Altiplanowas discovered in several temporary ditches. Conchological andanatomical characteristics of this snail are similar to thoseof Drepanotrema nordestense (Lucena 1953), a tropical planorbid snailreported from the northeastern region of Brazil. A comparative studywas carried out with the closely related species D. aeruginosumfrom Puerto Rico and Guadeloupe using morphological (shell andanatomy of the reproductive system) and genetic (allozyme) markers.This study confirmed a clear distinction between the two species.Several malacological surveys have been carried out in the NorthernBolivian Altiplano since the first field trip by D'Orbigny in1835, the last one in 1975. That D. nordestense and relatedspecies were not reported in these earlier surveys may indicatea relatively recent introduction. (Received 6 March 2000; accepted 1 June 2000)     

Take-off of Mould Spores in Relation to Wind Speed and Humidity

Using horizontal tube-cultures of various moulds belonging tothe genera Thamnidmmt, Phymatotrichum, Trichotheciwm, Ptptocephalis,Trichoderma, Mucor and Mycogone, the take-off of dispersal units(usually spores) under the influence of air currents of variousspeeds and of different humidities has been studied. It is foundthat in all the dry-spore forms the number of spores set freeincreases as the speed of the air stream rises. Further, atany given air-stream rate, the numbers of spores set free aregreatest in the first interval of time and rapidly fall offin subsequent intervals. In all species, spores are more readilyset free in air streams of relatively low as compared with thoseof relatively high humidity. Although Trichoderma viride hasbeen regarded as a slime-spore fungus, its conidia can readilybe blown from the conidiophores. No spores could be inducedto take off from Mucor ramarmianus even at the highest air speedsused.     

Photosynthesis and photorespiration in the genus Oryza

Photosynthetic gas exchange has been surveyed in 22 of the 23species currently placed in the genus Oryza and constitutingthe wild relatives of cultivated rice. Unimproved, wild germplasmof a number of species showed light-saturated assimilation ratesin atmospheric air at least as great as cultivars and elitebreeding material of the cultigen O. satlva. One of these specieswas O. australiensis, different accessions of which were significantly(P=0.001) superior in assimilation rate to the 0. satlva genotypestested, including representatives of the Indica, Japonica andJavanica subgroups. Amongst species, assimilation rate was correlatedpositively with light saturation and with carboxylation efficiency.The wild species fell into two distinct groupings accordingto whether they originated from sun or shade habitats, withthe higher assimilation rates being associated with the sunspecies. Assimilation rates were also higher in diploids thanin tetraploids and this was associated with the fact that allsun species are diploids and all tetraploids are shade species.The carbon dioxide compensation concentrations ranged from 28to 43µmol mol^–1 with the two lowest values (28 and32µmol mol^–1) coming from accessions of O. rufipogon.The mean value for the absolute quantum yield of photosynthesismeas ured on attached leaves was 0.060. There was a large rangein the activity of phosphoenolpyruvate (PEP) carboxylase witha number of species having rates several times those of C₃ species.Some species with the highest assimilation rates were assessedfor photorespiratory losses and these were generally around30% and similar to O. satlva cultivars. However, a range ofO. rufipogon accessions had photorespiration rates significantly(P=0.01) lower than the O. sativa genotypes tested. No speciesin the genus possessed C₄ photosynthetic metabolism though somedid overlap with compensation concentrations and phosphoenolpyruvatecarboxylase activities reported for C₃–C₄ intermediatespecies. The potential value of wild relatives to the improvementof cultivated rice is discussed. Key words: Oiyza, photorespiration, photosynthesis, rice, wild rice     

Nucleotide Sequence of a Putative Sensory Kinase Gene from the Cyanobacterium, Anacystis nidulans 6301

The nucleotide sequence of a 2,146 bp portion of the Anacystisnidulans (Synechococcus PCC6301) genome has been determined.This region contains an open reading frame (ORF) of 392 codons,whose predicted protein sequence shows partial homology to thoseof E. coli phoM and envZ. Hence ORF392 is suggested to be asensory kinase gene in cyanobacteria.     

An Isotopic Study of the Fixation of Nitrogen associated with Nodulated Plants of Alnus, Myrica, and Hippophae

Nodulated plants of Alnus glutinosa, Myrica gale, and Hippophaërhamnoides, the root systems of which had been exposed to excessfree ¹⁵N, showed substantial enrichment in fixed ¹⁵N contentin all parts of the plant, but particularly in the root nodules.The data resemble closely those obtained by the present andprevious authors with legumes under comparable conditions, andsupport the conclusion already drawn from experiments of traditionaltype that the nodules of these non-legumes are similar to thoseof legumes in their function and relation to the rest of theplant. Nodulated plants of Alnus and Myrica continued to fixfree nitrogen concurrently with the uptake of combined nitrogenwhen the latter was supplied in the rooting medium in amountsunlikely to be exceeded in the field. Isotopic tests on detachednodules of one of the species (Alnus glutinosa) showed thatfixation continued, and though much reduced as compared withthat shown by attached nodules it considerably exceeded thatexperienced by the present and previous authors with detachedlegume nodules, on the basis of fixation per unit of total nodulenitrogen. It is probable that detached Alnus nodules presentconvenient material for the further study of various aspectsof the fixation process.     

Exogenous Auxin and N-1 -Naphthylphthalamic Acid Effects on Populus deltoides Xylogenesis

A method was developed for evaluating the empirical alterationof xylem vessel differentiation in the central leaf trace ofPopulus deltoides, a species that exhibits helical phyllotaxis.Effects of experimental treatments for a period of six plastochronswere evaluated by vessel parameter ratios = 2.P_T/ (P_T+1 + P_T–1),where P was either vessel number or mean transverse vessel areameasured at mid-intern ode at Leaf Plastochron Indices of T– 1, T, and T + 1. Excising leaf laminae reduced vesselnumber and mean vessel area in the associated central leaf traceby 50% and 70%, respectively, compared to unexcised laminaecontrols. Replacing excised laminae with a concentration seriesof exogenous indoleacetic acid (IAA) resulted in a 5% increaseper log mol m^–3 of IAA in the number of vessels differentiatingin the associated central leaf traces compared to excised controls.Mean vessel areas within these leaf traces were 50% of thoseof intact leaf traces. No significant effects of different concentrationsof exogenously applied IAA on mean vessel area could be demonstrated.A lanolin paste ring of N-1 -naphthylphthalamic acid (NPA),an auxin transport inhibitor, around the petioles of intactleaves reduced the number of differentiating vessels by 7% andmean vessel area by 29% per log mol m^–3 of NPA comparedto central leaf traces of leaves ringed with plain lanolin paste.The results suggest that NPA treatments may be used to distinguishexperimentally, at least in part, the cell division from thecell enlargement phases of primary xylogenesis within centralleaf traces of P. deltoides stems. Key words: Auxin transport, Vessel area, Vessel number     

SPECIES DISCRIMINATION AMONG PELAGIC HETEROPODS: RESOLUTION OF THE PTEROTRACHEA HIPPOCAMPUS--P. MINUTA PROBLEM

Four species of Pterotrachea are currently recognized, two ofwhich (P. hippocampus Philippi, 1836, and P. minuta Bonnevie,1920) have very similar morphologies. These two species havebeen distinguished mainly on the basis of eye and visceral nucleusshapes; the former with wide, triangular eyes and a short, broadnucleus, and the latter with narrower, triangular eyes and ataller, more slender nucleus. Quantitative and qualitative morphologicaldata were obtained from specimens of P. hippocampus and P. minuta collectedduring two oceanographic sampling programs in the North AtlanticOcean. Comparisons of eye and visceral nucleus shapes (representedby their length to width and length to retinal width ratios,respectively), plotted against body length showed linear decreases,with no justification for the recognition of two separate species.Examination of eye shape across a wide range of body sizes showedthat the width of the retina increases disproportionately with bodygrowth (by elongation and medial upturning) beginning at a length ofabout 21-22 mm. As a result, the overall appearance of the eyeat this body size changes such that smaller animals (less than21-22 mm) have eyes corresponding with those of P. minuta, whilethe eyes of individuals larger than this body length match thoseof P. hippocampus. Several authors have distinguished femalesof the two species by the presence (P. hippocampus) or absence (P.minuta) of cuticular spines anterior to the eyes. Examinationof female specimens showed that those less than about 30 mmlacked these spines, while those above this size possessed them.Thus, cuticular spines represent a secondary female sexual characteristic. Other morphological features that have been used by previousauthors to distinguish the two species were examined and rejected.Because P. hippocampus was described prior to P. minuta, itis herein regarded as the senior synonym of P. minuta. (Received 12 June 1997; accepted 21 May 1999)     

Injury-induced Cyanogenesis in Vegetative and Reproductive Parts of Two Grevillea Species and their F1 Hybrid

When leaves of three Grevillea species were macerated, hydrogencyanide was only released from the soft, immature ones. Thebark but not wood of young stems was weakly cyanogenic. Thegreatest concentration of cyanoglucosides occurred in peduncles,flower buds, open flowers, immature seeds and germinants. Nocyanide was released from nectar, pedicels, dry fruit, elaiosomesand dry walls mature seeds. Addition of ß-glucosidase,and sometimes water only, increased cyanogenesis in young leaves,bark, some seed and fruit walls, and embryos of mature seeds.The endogenous levels of ß-glucosidase were sufficientto release all the cyanide present in at least 80% of cases. Young leaves and germinants of G. bipinnatifida (resprouter)released more cyanide than those of G. banksii, while flowerbuds, stigmatic region, styles, perianths and ovaries of G.banksii (non-sprouter) released far more cyanide than thoseof G. bipinnatifida. The interspecific and intraplant distributionof cyanoglucosides is consistent with the expected impact ofbeneficial and herbivorous animals on long term fitness of thesespecies. The F1 hybrid (G. 'Robyn Gordon') tended to have intermediatecyanoglucoside levels between the two putative parents.Copyright1993, 1999 Academic Press Grevillea bipinnatifida, G. banksii, G. 'Robyn Gordon', cyanide, herbivory, ß-glucosidase, cyanogenesis     

Adaptations of Host and Symbionts in the Intertidal Zone

SYNOPSIS. Different species of larval trematodes that utilizethe same intermediate host characteristically exhibit distinctivepatterns of response to environmental fluctuations. Not onlyare the responses distinctive for each species, but also theycannot be correlated with that of the host. The physiologicalresponses of the molluscan host to physical changes in the environment,however, are modified significantly by the presence of a larvaltrematode infection. The thermal metabolic acclimation patternsof infected Nassarius obsoleta are quite distinct from thoseof non-infected N. obsoleta. Thex activity patterns during thermalacclimation of cytochrome c oxidase from digestive glands ofsnails infected with different species of larval trematodesindicate that each species of larval trematodes differentiallyinfluences the hosttissue, so that the cytochrome oxidase systemdoes not respond to temperature in the same way as does uninfectedhost tissue.     

Free Sugars and Organic Acids in the Leaves of Various Plant Species and their Compartmentation Between the Tissues4

The distribution of free sugars and organic acids between theepidermis and mesophyll of Tulipa gesneriana L., Vicia fabaL., and Commelina communis L. leaves was studied using mainlygas-liquid chromatography. Fructose, glucose, sucrose, and myo-inositol were found in theepidermis and mesophyll of all three species. In T. geenerianaleaf tissues arabinose (trace levels), stachyose, tuliposidesA and B (mainly in the mesophyll), and xylose (trace levelsalso in V. faba tissues) were also detected. The acids were more difficult to detect and identify, beingat considerably lower concentrations than the sugars in bothtissues. Fumaric, citric, malic, ascorbic (trace levels), andan unidentified acid were common to the epidermis and mesophyllof all three species. Of special interest was the detectionof large amounts of glyceric acid in the epidermis and mesophyllof V. faba; this acid was not detected in the tissues from theother species. Fumaric acid was also very abundant in the epidermisof V.faba. A special study was made of the compartmentation of acids andsugars between the epidermis and mesophyll of T. geenerianaleaves after light and dark treatments. No changes in free acidor sugar levels were detected in the epidermis or mesophyllafter these treatments. Except for suceinic acid (P < 0·05),there were no statistically significant differences in acidlevels between the epidermis and mesophyll but for most of thesugars (myo-inositol, arabinose, and xylose being exceptions)differences were highly significant (P < 0·001), highestlevels occurring in the mesophyll. The differences in sugarlevels and the similarity in acid levels between epidermis andmesophyll of tulip leaves were considered to be essentiallydue to the different CO₂ fixing mechanisms and capacities ofthe two tissues. The energy source for the essentially non-greenepidermal tissue was discussed.     

Prediction and Measurement of the Decline in the Critical-K, the Maximum-K and Total Cation Plant Concentrations during the Growth of Field Vegetable Crops

The declines in maximum and critical K concentrations in plantdry matter of 16 different vegetable species were predictedfrom emergence to maturity by assuming that both were proportionalto the critical %N calculated in terms of plant dry matter perunit area using previously-described equations. Values of theproportionality constants were obtained from published measurementsmade, at commercial maturity, of crops grown in multi-levelfertilizer experiments. Predictions were tested: (a) againstmeasurements made at intervals during growth in experimentsreceiving a single level of fertilizer; (b) against measurementsmade of the highest K concentrations measured at the seedlingstage in soil-K gradient experiments; and (c) against the resultsof a K-fertilizer-response experiment in which harvests werecarried out at intervals during growth. Results were consistentwith the predictions and, thus, with the view that both criticaland maximum K concentrations are proportional to critical %Nthroughout growth. K concentrations in plant tissue water fluctuatedwidely during the growing season and values, averaged over theentire growing period for each of ten crops, varied by a factorof 3. These values were proportional to the mean cation concentrations(meq l^-1) calculated by assuming that all the ions were in solution.Total cation concentration (meq 100 g^-1) of dry matter was linearlyrelated to critical N concentration. Evidence was also obtainedthat maximum K concentration, critical K concentration and totalcation concentration (meq 100 g^-1) during growth were linearlyrelated to relative growth rate, provided that crop weightswere greater than 2 t ha^-1dry matter. A hypothesis was developedto co-ordinate these findings.Copyright 1998 Annals of BotanyCompany. Vegetable crops, cation, plant potassium, plant nitrogen, critical concentration, relative growth rate, plant weight.     

Canopy Photosynthesis of Tomato, Cucumber and Sweet Pepper in Greenhouses: Measurements Compared to Models

Two models for canopy photosynthesis (modified versions of thoseof Acock et al. , 1978 and of Thornley, 1976) were examinedby comparison with experimental photosynthesis data of cucumber(Cucumis sativus L.), sweet pepper (Capsicum annuum L.) andtomato (Lycopersicon esculentum Mill.). The data were obtainedin six large-scale, long-term, semi-commercial cultivationsin greenhouses (Nederhoff and Vegter, 1994). Measured environmentalconditions and measured LAI were input to the model. The emphasiswas on the models' sensitivity to the prevailing CO₂ concentration. The (modified) Acock model with 'standard' (originally published)parameters underestimated the photosynthesis rate. This modeltuned to one of our experimental data sets did not fit verywell to the other data sets. As expected, if the model was tunedto each particular data set, it was fairly in agreement withthe measurements, but the fitted parameter values were sometimesquestionable. With the (modified) Thornley model it was obligatoryto estimate or tune the light extinction. The model performedreasonably if all parameters were tuned and also if only thelight extinction was tuned. The modified models were considered usable for practical applications,after parameter tuning. As the sensitivity to CO₂ was not alwaysequal among the models and the measurements, care should betaken when applying the models for CO₂ supply control.Copyright1994, 1999 Academic Press Canopy photosynthesis, Capsicum annuum L., carbon dioxide, cucumber, CO₂, Cucumis sativus L., glasshouse, greenhouse, Lycopersicon esculentum Mill., measurements, model, sweet pepper, tomato     

Elucidation of the mechanism enhancing the avidity of lectin with oligosaccharides on the solid phase surface

The mechanism underlying molecular recognition of lectins waselucidated by a novel solid phase binding assay system basedon surface plasmon resonance. When the apparent affinities ofinteractions between chitooligosaccharides and wheat germ agglutininwere compared between lectin-immobilized and oligosaccharide-immobilizedassay systems, the affinity constants (Ka) calculated for theformer system were in good agreement with the previously reportedvalues measured in solution. On the other hand, in the lattersystem, the calculated Ka could be more than 10,000 times higherthan the values in solution at lower lee tin concentrations.To elucidate the reason for this, we systematically investigatedthe effects of the oligosaccha-ride immobilized density andthe lectin valence on the apparent affinity in the oligosaccharide-immobilizedassay system. Both the apparent association (k_ass) and dissociationrate constants (k_diss) showed a tendency to decrease as theoligosaccharide density increased. This effect was most remarkablefor the interaction possessing an extremely fast intrinsic K_ass.Oligomerization of lectin enhanced the avidity due to a significantreduction in k_diss. These phenomena could be explained by consideringthe nonhomogeneous conditions under which binding occurred.The reaction in a nonhomogeneous state is limited by the masstransport effect, and the effect of rebinding becomes so largethat it cannot be disregarded. These findings are the firstto demonstrate the importance of the mass transport effect inmodulating the affinity of lectin for oligosaccharides on asolid phase surface. avidity clustering effect lectin mass transport surface plasmon resonance     

Diurnal rhythm in the Hill reaction in cell-free extracts of the green alga Bryopsis maxima

A diurnal rhythm was found in the Hill reaction in cell-freeextracts of the green alga Bryopsis maxima. The rate of photoreductionof 2,6-dichloroindophenol showed a rhythm synchronized withthat of photosynthetic O₂ evolution. A diurnal rhythm was alsoobserved in the rate of O₂ evolution accompanying the reductionof P-benzoquinone with phase and frequency similar to thoseof the rhythm of photosynthesis. These results indicate thata regulation mechanism underlying the photosynthesis rhythmexists in the photosynthetic electron transport chain in chloroplasts. ¹ Present address: Mitsubishi Yuka Laboratory of Medical Science,Narimasu, Itabashi, Tokyo 175, Japan. (Received January 6, 1979; )     

Acclimation of Respiratory Properties of Leaves of Spinacia oleracea L., a Sun Species, and of Alocasia macrorrhiza (L.) G. Don., a Shade Species, to Changes in Growth Irradiance

To clarify the way in which the light available for growth affectsrespiration in leaves of sun and shade plants, we examined therespiratory properties of mature leaves of Spinacia oleraceaL., a sun species, and of Alocasia macrorrhiza (L.) G. Don.,a shade species, that had been grown at various irradiances.In leaves of S. oleracea, the respiratory rates, on a dry massbasis, decreased with time during the night, and the higherwas the growth irradiance during the day, the higher was therespiratory rate. The marked decreases in the respiratory rateduring the night were accompanied by decreases in the concentrationof carbohydrates in the leaves. By contrast, the respiratoryrates of leaves of A. macrorrhiza were virtually constant throughoutthe night and the absolute rates were lower than those of S.oleracea even though the absolute value of the concentrationof carbohydrates and its decrease at night resembled to thosein S. oleracea. The maximum activities of respiratory enzymeswere also similar to those in S. oleracea. However, the leavesof A. macrorrhiza contained less soluble protein than thoseof S. oleracea. These results suggest that, in S. oleracea,the concentration of carbohydrates might determine the respiratoryrate while such is not the case in A. macrorrhiza. The lowerrespiratory rates in A. macrorrhiza might be due to a lowerdemand for ATP. (Received November 29, 1995; Accepted February 15, 1996)     

SPERM AND SPERMIOGENESIS IN OPISTHOTEUTHIS PERSEPHONE (OCTOPODA: CIRRATA): ULTRASTRUCTURE, COMPARISON WITH OTHER CEPHALOPODS AND EVOLUTIONARY SIGNIFICANCE

Ultrastructural features of spermiogenesis and mature spermatozoaare described for the first time in a cirrate octopod. Comparisonwith other investigated cephalopod species shows that spermatozoaof Opisthoteuthis persephone Berry most closely resemble thoseof the genus Octopus. The shared features include: (1) an elongate,solid acrosome with internal banding and a prominent helicalkeel; (2) a straight, rod-like nucleus; (3) a short midpieceand (4) a post-mitochondrial (‘annular’) skirt.Of these, the acrosomal morphology is most significant taxo-nomically,as the internal banding of the acrosomal vesicle only occursin the Octopoda. Spermatozoa of Opisthoteuthis and Octopus differhowever in the extent of the internal banding of the acrosome(poorly developed in Opisthoteuthis) and substructure of theacrosomal keel (more complex in Opisthoteuthis). Surprisingly,the extensive fibrous plug of Octopus and Vampyroteuthis sperm,is not developed either in Opisthoteuthis or in Eledone. Resultsprovide additional support for the monophyly of the Octopodabut also hint at the possibility that some groups of in-cirratesmay not be as advanced as generally believed. (Received 6 July 1992; accepted 18 August 1992)