Verteilung und Aufteilung der DNS bei einigen Cyanophyceen,festgestellt durch ihre DAPI-Fluoreszenz

The DNA of Blue-Green Algae may be specifically and most efficiently elucidated by the combined use of the fluorochrome DAPI and DNAse treatment. InChroococcus turgidus andSynechococcus aeruginosus it forms a network which usually is positioned at the periphery of the centroplasm. At the beginning of cell division it seems to be invaginated by the ingrowing cell wall. Later it must be distributed by other means because two equal parts are connected by a number of fine and straight DNA threads. InOscillatoria limosa usually all parts of the centroplasm are interspersed with the DNA network. In surface view, the DNA occasionally seems to consist of a number of independant rods, but in reality these are connected to the general network. Division apparantly occurs by ingrowth of the crosswall and usually results in equal daughter nuclear equivalents although occasionally they are unequal. Four strains ofMicrocoleus vaginatus were found to have nuclear equivalents of the same general appearance as inOscillatoria limosa.

     

Variation of Giemsa C-band and fluorochrome banded karyotypes,and relationships inAllium subgen.Molium

The somatic karyotypes of 10 taxa belonging toAllium subgen.Molium (Liliaceae) from the Mediterranean area have been investigated using Giemsa C-band and fluorochrome (Hoechst, Quinacrine) banding techniques. A wide range of banding patterns has been revealed. InAllium moly (2n = 14),A. oreophilum (2n = 16) andA. paradoxum (2n = 16) C-banding is restricted to a region on each side of the nucleolar organisers and the satellites show reduced fluorescence with fluorochromes. The satellites are also C-banded and with reduced fluorescence inA. triquetrum (2n = 18), but two other chromosome pairs also have telomeric bands which are not distinguished by fluorochrome treatment. InA. erdelii (2n = 16) 4 pairs of metacentric chromosomes have telomeric C-bands while 2 pairs of telocentric chromosomes have centromeric C-banding. InA. subhirsutum (2n = 14),A. neapolitanum (2n = 28),A. trifoliatum subsp.hirsutum (2n = 14) andA. trifoliatum subsp.trifoliatum (2n = 21) chromosomes with long centromeres, consisting of a centromere and nucleolar organiser are positively C-banded on each side of the constriction. InA. subhirsutum banding is confined to the pair of chromosomes with this feature, whereas inA. neapolitanum one additional chromosome pair has telomeric bands and inA. trifoliatum there are varying numbers of chromosomes with centromeric and telomeric bands, depending on the subspecies.A. zebdanense (2n = 18) shows no C-bands. The banding patterns in this subgenus are compared with those recorded for otherAllium species and with the sectional divisions in the genus. Evidence from the banding patterns for allopolyploidy inA. trifoliatum subsp.trifoliatum andA. neapolitanum is discussed.     

Floral development and systematics ofCistaceae

The floral development of representatives of six genera ofCistaceae has been studied. Calyx development involves the formation of a ring primordium in several taxa. Androecium development in species with intermediate or higher stamen numbers starts with the formation of a ring meristem on which the stamens are initiated in a centrifugal direction. In many taxa five alternipetalous leading stamen primordia can be observed. In the apetalous (cleistogamous) flowers ofTuberaria inconspicua androecium development appears to be unordered; this is probably due to the lack of petals. InLechea intermedia (also cleistogamous) the corolla is trimerous and three complex stamen primordia are produced, which give rise either to one or three stamens. Relationships withinCistaceae are discussed. Floral development inCistaceae is compared with that in otherMalvanae. Among the eight families ofMalvanae from which information on floral development is availableCochlospermaceae andBixaceae exhibit the greatest similarities toCistaceae. InCistaceae the leading stamen primordia are alternipetalous. InBixa the same condition seems to be present. InMalvales s. str. mostTiliaceae also show earliest stamen initiation in alternipetalous sectors, whereas the stamens of the innermost alternipetalous position are retarded early or even suppressed inSterculiaceae, Bombacaceae, andMalvaceae. WithinMalvales s. str. the diversity of androecial developmental patterns seems to decrease inBombacaceae andMalvaceae due to increasing synorganization in the mature androecium. The derivation of polyandry inMalvanae from diplo- or obdiplostemony is discussed by comparison with the sister clades ofMalvanae as shown in recentrbcL studies (i.e.Sapindales, Rutales, the glucosinolate producing clade, andMyrtales).     

Paraveinal mesophyll: Review and survey of the subtribeErythrininae (Phaseoleae,Papilionoideae, Leguminosae)

Paraveinal mesophyll (PVM) is a distinctive anatomical feature of the leaf mesophyll of some plant taxa that may represent a specialized physiological compartment. A comprehensive review of the 42 published references that mention PVM or similar cell layers and a survey of 121 of the 272 species of all nine genera of thePhaseoleae subtribeErythrininae demonstrate that PVM is nearly exclusively found inLeguminosae. InLeguminosae, PVM is either rare or absent in subfamilyCaesalpinioideae, uncommon inMimosoideae, and extensively distributed amongPapilionoideae. In subtribeErythrininae, PVM is ubiquitous inErythrina, and occurs in four other genera. ThreeErythrininae genera (Apios, Mucuna, andCochlianthus) lack PVM. Unique chloroplast-poor, enlarged conical cells (pellucid palisade idioblasts) occur in 80 species ofErythrina but not in any other genus ofErythrininae.     

Plasticity in courtship and sneaking behaviors depending on tail length in the male guppy, <Emphasis Type="Italic">Poecilia reticulata</Emphasis>

Male guppies Poecilia reticulata exhibit two types of mating behavior, i.e., courtship displays for cooperative copulation and sneaking attempts for forced copulation. The frequencies of the two male mating behaviors are influenced by tail length. Males possessing long tails exhibit courtship displays less frequently and sneaking attempts more frequently than those possessing short tails, even though they have similar total lengths. To examine whether these male behavioral tendencies depending on tail length are genetically controlled or are determined by tail length per se, tail length manipulation was conducted. The tail lengths of males that had previously possessed longer tails were surgically shortened to a greater degree than those of their counterparts that had previously possessed shorter tails. Although the frequencies of the mating behaviors exhibited by the latter males did not apparently change, the former males clearly increased the frequency of courtship displays and decreased that of sneaking attempts following tail shortening. These results indicate that males adjust the frequencies of the two mating behaviors according to their tail length. Since females avoid cooperative mating with males possessing long tails, the change in mating behavioral patterns by males depending on their tail length may increase their mating opportunities.     

Variation and Repeatability of Calling Behavior in Crickets Subject to a Phonotactic Parasitoid Fly

Male Teleogryllus oceanicus (Orthoptera: Gryllidae) produce a conspicuous calling song to attract females. In some populations, the song also attracts the phonotactic parasitoid fly Ormia ochracea (Diptera: Tachinidae). I examined the factors affecting calling song by characterizing the calling behavior of caged crickets from an area where the fly occurs. Calling activity (proportion of time spent calling) was repeatable and a significant predictor of female attraction. However, calling activity in the parasitized population was lower than in an unparasitized Moorea population (Orsak, 1988), suggesting a compromise between high activity to attract females and low activity to avoid flies. Calling activity peaked simultaneously with fly searching, so crickets did not shift to calling when the fly is less active. Males harboring larvae did not call less than unparasitized males; however, a more controlled study of the effects of parasitization on calling behavior is needed to evaluate this result. The results are discussed in the context of other studies of the evolutionary consequences of sexual and natural selection on cricket calling behavior.     

Floral ontogeny in tribe Dalbergieae (Leguminosae: Papilionoideae):Dalbergia brasiliensis, Machaerium villosum s. l.Platymiscium floribundum, andPterocarpus rotundifolius

Floral organogenesis and development of the tropical legume treesDalbergia brasiliensis, Machaerium villosum, Platymiscium floribundum, andPterocarpus rotundifolius were studied using scanning electron microscopy. The aims were to compare ontogenies and to elucidate if floral ontogenetic data will provide new character states diagnostic of the tribe Dalbergieae, which is considered a basal papilionoid tribe and primarily defined on fruit characters. Organ inception is principally acropetal in all taxa studied. Carpel inception is, however, consistently precocious. InD. brasiliensis sepals are initiated in an order not previously reported in Papilionoideae. It may be considered modified helical. InP. rotundifolius the inner whorl of stamens initiate in an unusual way, this is lateral two stamens first, then the two abaxial ones, and last the adaxial one, opposed to the unidirectional order usually seen in Papilionoideae. Generally the differences in flower development among the studied genera appear at initiation and late stage in ontogenesis, rather than at mid-stage.     

The swimming and feeding behavior of Mesocyclops

The swimming and feeding behaviors of Mesocyclops are described from a review of the literature and personal observations. Mesocyclops exhibits considerable behavioral flexibility in response to environmental stimuli. Mesocyclops edax exhibits an increase in horizontal looping behavior at high prey densities, and performs a tight vertical looping behavior in response to the loss of captured prey. Ingestion rates by Mesocyclops are a complex function of prey density, morphology, and behavior in addition to prey size. Vertebrate predators induce a rapid escape response in Mesocyclops and may be responsible at least in part for their extensive diel vertical migrations. The complex behavioral patterns of Mesocyclops suggest that its distribution and abundance in nature will be distinctly nonrandom and influenced as much by its own behavioral responses as by other external physical factors such as water circulation patterns.     

Umbilicaria freyi spec. nova und der Formenkreis vonUmbilicaria hirsuta in Europa (Lichenes,Umbilicariaceae)

InUmbilicaria hirsuta andU. grisea the so-called soredia originate from structured plectenchyma of the upper thallus layer (thus contrasting with true soredia, which are pushed off from unstructured medullar plectenchyma), and, therefore, are termed parasoredia. Both species have been regarded to comprise (in western Europe) forms with relatively large thalli and a pale lower surface; rhizinomorphs may be present (with varying density) or absent; propagation is not by parasoredia, but by flattened diaspores (schizidia s. l.) These forms are united here and described as a separate species:U. freyi (syn.U. hirsuta var.pyrenaica Frey andU. grisea resp.murina f.subpapyria Frey). So far, the species is known to occur from the western Alps through C. France to the Pyrenees, C. Spain and Italy including Sardinia.

Herrn Prof. Dr.Lothar Geitler zum 90. Geburtstag gewidmet.     

Kin recognition of worker brood by worker honey bees,Apis mellifera L.

Experimental colonies of honey bees consisting of two patrilines were observed as they reared worker brood. Seven behavior patterns that relate to brood care were recorded. Worker bees biased the care they provided to eggs and larvae destined to become workers on the basis of brood patrilines. Both patrilineal and antipatrilineal preferences in various behavioral patterns were observed. There was variation among colonies that may have been the result of the frequencies of brood of each patriline and the total amount of brood available to be reared. In addition, there were some differences between workers of the two patrilines in the way that they cared for the two patrilines of brood.     

Studies on systematic embryology inScilla (Hyacinthaceae)

Scilla persica and 5 species of the so-calledS. hohenackeri group, namely,S. furseorum, S. puschkinioides, S. vvedenskyi, S. hohenackeri, andS. greilhuberi, have been investigated embryologically with special reference to embryo sac and endosperm development.Polygonum-type embryo sac development was stated inS. puschkinioides andS. greilhuberi. 8-nucleate, normally structured embryo sacs, which could not be specified further due to sparse availability of the material, were stated inS. furseorum, S. vvedenskyi, andS. hohenackeri. InS. persica the embryo sac develops according to the bisporicAllium-type. In most species endosperm development was stated to be nuclear, exceptS. hohenackeri, where the type could not be specified. Other traits of possible taxonomic significance are the number of layers in the outer integument, which is mostly 4, or 5–6 inS. furseorum, and the occurrence of polyploid versus haploid and early degenerating antipodal nuclei, the latter occurring only inS. persica andS. furseorum. These embryological characters may be useful for assessing taxonomic relationship of the present species with other allied groups withinScilla, in particular, theS. siberica alliance,S. messeniaca, and theS. bifolia alliance. TheAllium-type embryo sac, which occurs inS. persica, is also characteristic for theS. siberica alliance, and may be a common derived character. Lack of antipodal polyploidization, as characteristic forS. persica andS. furseorum, occurs also in theS. siberica alliance, and is perhaps another common derived trait indicating phylogenetic relationship. Nuclear endosperm development is more frequent in spring-flowering squills than helobial development, which has previously been stated inS. messeniaca, some species of theS. siberica alliance, and inS. litardierei. While helobial endosperm may be primitive forHyacinthaceae in general, it may, by reversal, also occur as a derived character, at least in some species of theS. siberica alliance.     

Rearing phonotactic parasitoid flies [Diptera: Tachinidae,ormiini, ormia spp.]

Females of ormiine tachinids fly to their hosts' calling songs and deposit larvae on the host or nearby. Two species,Ormia ochracea (Bigot) andO. depleta (Wiedemann), were reared for at least 8 generations, making them the first ormiines to be laboratory-propagated. Both were reared on natural hosts:Gryllus spp. field crickets (principallyG. rubens) forO. ochracea, andScapteriscus spp. mole crickets forO. depleta. Commercially rearedAcheta domesticus tested as hosts were less satisfactory. Hosts were parasitized manually or by confinement with flies or planidia (infective larvae). Transparent, cylindrical, sleeved cages were designed to accommodate parasitized hosts and pupae and adults ofO. ochracea. Cages were joined to allowO. ochracea to cycle through its stages with minimum handling and care. Parasitized hosts and pupae ofO. depleta were held in containers of damp sand; adults were held in cages developed forO. ochracea. Adults of both species were maintained on applesauce, sugar cubes, powdered milk, and water. The life cycle ofO. ochracea was about 31 days and ofO. depleta about 36 days, with the principal difference being the time required for planidia to complete development. InO. ochracea the adults emerged synchronously but inO. depleta males preceded females. In both species sex ratio was generally I: 1 and females lived slightly longer than males.O. depleta from our laboratory colony have been released for biological control of mole crickets.      

Gametogenesis,endosperm development,and embryogeny inMicrocarpaea muscosa (Scrophulariaceae,Gratioleae)

InMicrocarpaea muscosa gametogenesis, embryo sac development (Polygonum type), endosperm development (cellular), embryogeny (Onagrad type), and seed structure are described. The different modes of endosperm development withinGratioleae are compared.     

Pollen limitation in three sympatric species ofVaccinium (Ericaceae) in the Upper Ardennes, Belgium

The reproductive success of three co-flowering species ofVaccinium (V. myrtillus, V. vitis-idaea andV. uliginosum) was studied in one heathland of the Upper Ardennes, Belgium, during three years (1988–1990). The purpose was to examine whether pollen limitation, flower position and flowering phenology may influence patterns of fruit set in these three sympatric species. I quantified fruit and seed set following supplementary hand-pollinations and compared this to natural fruit set. On the same plants, I also quantified fruit and seed set in relation to the spatial position of the flowers on the ramet and their temporal sequence of blooming. Hand-pollination had no significant effect on fruit set inV. vitis-idaea andV. uliginosum, but significantly increased seed number per fruit in 1989. InV. myrtillus both fruit and seed set were increased by supplementary pollination, but significantly in only one year. Analyses of position effects revealed that the fruits in the lower positions in the ramet did not mature preferentially and did not contain more seeds inV. uliginosum and inV. vitis-idaea. Flowering phenology also had no significant effect for these species. InV. myrtillus hand-pollinated flowers showed a seasonal decline in seed number, and control (naturally pollinated) flowers showed a seasonal increase in fruit set. Fruit and seed set appear to be pollen-limited rather than resource-limited inV. uliginosum. In the two other species, unfavorable weather (frosts) could be a more important cause of low fruit and seed set.     

B-Chromosomes inAllium flavum (Liliaceae) and some related species

B-Chromosomes ofAllium flavum, A. stamineum andA. carinatum were C-banded. InA. flavum different types of B's were found, one of them possessing a nucleolus organizer. In the B's ofA. flavum andA. stamineum the banding patterns resemble those found in the standard chromosomes. The B inA. carinatum is only terminally banded. InA. flavum chiasma localization in the B's appears to be dependent on C-band location, just as is the case in the A-chromosomes. An increase in B's was found to cause a small (but significant) increase in chiasma frequency in the PMC's. This may result from an alteration in the nucleotype by the B's.     

Diel vertical migrations of invertebrate predators (Leptodora kindtii ,Thermocyclops taihokuensis, andMesocyclops sp .) in a shallow, eutrophic lake

We studied vertical distribution patterns of three invertebrate predators – Leptodora kindtii, Mesocyclopssp., and Thermocyclops taihokuensis– in a shallow eutrophic lake, Lake Suwa , Japan. From June to October in 2000 and 2001, we collected samples in the lake center in order to examine the vertical distribution patterns and the densities of the predators in the water column during the day (0900) and at night (2330). We also examined phototactic behavior of Leptodora in the laboratory. The three invertebrate predators showed clear migration patterns. Leptodora and Thermocyclops displayed a typical migration, avoiding the surface and maintaining a high abundance in deeper water during the day, and being distributed uniformly during the night. Mesocyclops, on the other hand, showed no clear vertical distribution pattern in the water column. However, Mesocyclops showed higher densities in the water column during the night than during the day. It suggests that they stayed just above the bottom during the day and migrated upward during the night. Leptodora also showed such a density difference between day and night. In the laboratory, Leptodora showed strong negative phototactic behavior. The observed density changes between day and night in Leptodora and Mesocyclops suggests the possible underestimation of their population density by usual sampling methods, and thus the impact of predation on populations of prey zooplankton species may also be underestimated in shallow water bodies.     

Auxospore formation inLicmophora (Bacillariophyta)

InLicmophora gracilis var.anglica two auxospores are produced per pair of mother-cells, through the allogamic fusion of migratory and stationary gametes. Both active gametes are produced from the same mother-cell and hence both zygotes are formed in the other mother-cell. Pairing can occur between two stalked cells, or between a stalked cell and a detached cell; in the latter case the migratory gametes derive from the detached cell. The auxospores expand parallel to one another and to the apical axis of the donor mother-cell. Behavioural anisogamy of this kind, which may be termed thecis-type, seems to be characteristic of most araphid pennates and contrasts with thetrans-type exhibited byCymbella, Gomphonema and some other raphid taxa, where each mother-cell produces one migratory and one stationary gamete.     

Temperature Effects on the Temporal Properties of Calling Songs in the Crickets <Emphasis Type="Italic">Gryllus fultoni</Emphasis> and <Emphasis Type="Italic">G. vernalis</Emphasis>: Implications for Reproductive Isolation in Sympatric Populations

Two closely related wood-cricket species, Gryllus fultoni (Orthoptera: Gryllidae) and G. vernalis, produce similar calling songs, consisting of 3-pulse chirps. Analysis of field and laboratory recordings of calling songs showed that, after correction to a common temperature, there was a divergence in chirp and pulse rates between far allopatric populations of G. fultoni and populations sympatric with G. vernalis. To determine whether the divergence in calling songs potentially provides reproductive isolation between G. fultoni and G. vernalis throughout the temperature range over which these insects sing, we recorded calling songs of lab-reared G. fultoni and G. vernalis populations between 18 and 28°C. Mean chirp rate significantly differed between sympatric and far allopatric G. fultoni populations as well as between sympatric G. fultoni and G. vernalis populations. Although there was a significant difference in mean pulse rate between sympatric G. fultoni and G. vernalis populations, pulse rate did not differ between sympatric and far allopatric G. fultoni populations in the laboratory study. Considering the magnitudes of differences in calling song characters discriminated by females of G. fultoni and the mean differences and the variability in calling song characters between the two species, the joint difference in chirp and pulse rates may be adequate for species discrimination over most of the range at which these crickets breed.     

Veratridine induces a Ca2+ influx,cyclic GMP formation,and backward swimming inParamecium tetraurelia wildtype cells and Ca2+ current-deficient pawn mutant cells

Summary Veratridine opens voltage-dependent Na⁺ channels in many metazoans. InParamecium, which has voltage-dependent Ca²⁺ channels and a Ca/K action potential, no such Na⁺ channels are known. A Ca-inward current is correlated to an intracellular increase in cGMP. The addition of veratridine toParamecium wildtype and to pawn mutant cells, which lack the Ca-inward current, transiently increased intracellular levels of cGMP about sevenfold to 40 pmol/mg protein. A half-maximal effect was obtained with 250 m veratridine. The increase in cGMP was maximal about 15 sec after the addition of veratridine and declined rapidly afterwards. Intracellular cAMP levels were not affected. The effect of veratridine on cGMP was dependent on the presence of extracellular Ca²⁺. The time dependence and extent of stimulation closely resembled the effects observed after stimulation by Ba²⁺, which causes the repetitive firing of action potentials, Ca-dependent ciliary reversal, and cGMP formation. The effects of Ba²⁺ and veratridine were not additive. Wildtype cells and, surprisingly, also pawn mutant cells showed avoiding reactions upon addition of veratridine indicating that it induced a Ca²⁺ influx into the cilia, which causes ciliary reversal. The potency of veratridine to stimulate cGMP formation was little affected by Na⁺ in wildtype cells, three pawn mutant strains, and in the cell line fast-2, which is defective in a Ca-dependent Na-inward current. Divalent cations (Ca²⁺, Mg²⁺, and Ba²⁺) inhibited the effects the veratridine similar to metazoan cells. The results indicate that veratridine can open the voltage-operated Ca²⁺ channels inParamecium wildtype and, most interestingly, in pawn mutant cells. The pawn mutation is suggested to represent a defect in the activation of the Ca²⁺ channel. This explains the lack of differences in ciliary proteins between wildtype and pawn cells reported earlier.     

Responses of the ciliates <Emphasis Type="Italic">Tetrahymena</Emphasis> and <Emphasis Type="Italic">Paramecium</Emphasis> to external ATP and GTP

The unicellular ciliates Paramecium and Tetrahymena are the simplest eukaryotic cells to show reliable depolarizing responses to micromolar concentrations of external ATP and GTP. Their simplicity allows for combined analysis of swimming behavior, electrophysiology, receptor binding, behavioral mutant and drug screens as well as molecular genetic approaches such as RNAi and gene knockouts experiments. ATP and GTP are depolarizing chemorepellents in both ciliates, producing measurable receptor potentials and Ca²⁺-based action potentials that are correlated with jerking behaviors called avoiding reactions (AR). GTP also causes repetitive continuous ciliary reversals (CCR) and oscillating plateau depolarizations in Paramecium. Both ciliates show high affinity, saturable external binding of ³²P-GTP and ³²P-ATP but GTP does not compete for ATP binding and vice versa. Chemosensory adaptation occurs after continued exposure (15 min) to these ligands, producing a loss of external binding and forward swimming. However, cells adapted to ATP still bind and respond to GTP and GTP-adapted cells still bind and respond to ATP. This, combined with pharmacological analyses, suggests that there are two separate receptor systems: A metabotropic ATP receptor pathway and a different, novel GTP receptor pathway. A Paramecium mutant (ginA) lacks the GTP-induced oscillating depolarizations but does show AR in GTP, unveiling isolated GTP-receptor potentials for study. An ecto-ATPase is also present that may be involved in inactivation of ATP and GTP signals. Gene knockout experiments are currently underway to determine the roles of the ecto-ATPase and a putative 7-transmembrane spanning receptor in these responses.