Classification of amphipod compound eyes — The fine structure of the ommatidial units (Crustacea,Amphipoda)

Summary The ultrastructure of the compound eyes of 13 amphipod species has been investigated. An amphipod type of compound eye can be characterized by the constellation and consistency of a number of morphological features, most of which are also found in other compound eyes. The amphipod eye falls into four sub-categories (types). The ampeliscid type has a tripartite aberrant lens eye; the lysianassid type has a reduced or no dioptric apparatus and a hypertrophied rhabdom; the hyperid type possesses a large number of ommatidial units with long crystalline cones and dark instead of reflecting accessory pigment; and finally, the gammarid type can be interpreted as a generalized amphipod type. The lysianassid type is adapted to low light intensities and demonstrates convergent development with the compound eyes of other deep-sea crustaceans. The ampeliscid type is more similar to the gammarid type. The type characterization of the amphipod compound eye might well serve as a basis and incentive for functional studies also revealing adaptational mechanisms.This paper is dedicated to Professor Erik Dahl on his 65th birthday and retirement from the Chair of Structural Zoology, Department of Zoology, University of LundThe investigation has been supported by grants from the Swedish Natural Science Research Council (Grants 2760-009 and 009-43). Our thanks are due to the staffs of the marine biological stations in Espegrend (Norway) and Kristineberg (Sweden) and of the research vessel Jean Charcot, Brest, France. The skilled technical assistance of Mrs. Rita Wallén and Miss Maria Walles is gratefully acknowledged     

Isolation and identification of major ecdysteroids from the pycnogonidPycnogonum litorale (Ström) (Arthropoda,Pantopoda)

Summary From adults ofPycnogonum litorale (Ström) eight ecdysteroids were isolated by HPLC and identified by mass spectrometry and NMR. One of the compounds is 20-hydroxyecdysone, two further ecdysteroids show no OH-group at C-22 (22-deoxy-20,26-dihydroxyecdysone, 22-deoxy-20-hydroxyecdysone=taxisterone). The five other compounds are esters of ecdysteroids with acetic acid (25R and 25S isomers of 20,26-dihydroxyecdysone 22-acetate, 20-hydroxyecdysone 22-acetate) or with glycolic acid (20-hydroxyecdysone 22-glycolate, ecydsone 22-glycolate). The latter are new among zoo- and phytoecdysteroids. No significant amounts of ecdysone could be detected. The origin of the ecdysteroids inPycnogonum litorale and their biological activity are discussed.Abbreviations RP-HPLC Reversed-phase high performance liquid chromatography - NP normal phase - RIA radioimmunoassay - NMR nuclear magnetic resonance - FT Fourier transform - CI/D chemical ionization/desorption - TFA trifluoroacetic acid - E ecdysone - 20E 20-hydroxyecdysone - 2026E 20 26-dihydroxyecdysone     

The “sapucaia” group of Lecythis (Lecythidaceae)

Four previously much confused species of Lecythis, which form a coherent group of species collectively known in Brazil as “sapucaias,” are described and differentiated in a key. A summary of their pollination and dispersal is presented as well as of their present-day distributions in relation to past geological and climatological events. Fruit variability, the cause of name proliferation in this group, is described and related to the problem of species concepts in the Lecythidaceae.     

The extinct Baltic amber genus Propelma Trjapitzin,a valid genus of Neanastatinae (Hymenoptera,?Eupelmidae)

The extinct Eocene Baltic amber genus Propelma Trjapitzin 1963 is removed from synonymy under Eupelmus Dalman 1820 (Hymenoptera, Eupelmidae, Eupelminae) and treated as a valid genus within Neanastatinae Kalina 1984 based on examination of the holotype female of Propelma rohdendorfi Trjapitzin. Propelma rohdendorfi is redescribed, illustrated by photomacrographs, and compared to other described extant and extinct genera of Neanastatinae. Taxonomic, morphological and geological diversity of Neanastatinae relative to Eupelminae and Calosotinae is also discussed relative to potential age of the subfamily.     

The Diplommatinidae of Fiji – a hotspot of Pacific land snail biodiversity (Caenogastropoda,Cyclophoroidea)

The minute (adult size 1.3–4.8 mm) land snail species of the family Diplommatinidae in the Fiji archipelago are revised based on historical material and modern (1998–99) collections targeting limestone outcrops on the largest island, Viti Levu, and several smaller islands in the Lau group. The forty-two species (including 30 new species) belong to the genera Moussonia Semper, 1865, Palaina Semper, 1865 and Diancta Martens, 1867, which are briefly characterized and keyed. The diagnostic structure of the inner lamellar system of each species is illustrated. All species except one are endemic to Fiji. In Viti Levu, the 12 localities surveyed each had 1–13 (average 5) species of Diplommatinidae; ten species were each found at a single site only. In the Lau islands, five islands were visited, with 1–4 species per island; four species are known from single islands. The number of historically known species not recollected in 1998–99 (7 species), the number of single-site occurrences (14 species), and the numerous islands — including limestone islands — that have not been surveyed at all, indicate that the 42 species of Diplommatinidae currently known from Fiji represent perhaps only half of the Fiji diplommatinid fauna. Such numbers approach the diplommatinid diversity of Palau (39 described and more than 60 undescribed species), and surpasses by far the diversity of other South Pacific archipelagos of comparable land area (New Caledonia, Vanuatu, Samoa).Nomenclatural acts: Lectotypes designated: Diplommatina fuscula, Diplommatina fuscula var. vitiana, Diplommatina godeffroyana, Diplommatina godeffroyana var. latecostata, Diplommatina tuberosa, Diplommatina martensi var. macrostoma, all Mousson, 1870. Neotypes designated: Diplommatina subregularis, Diplommatina ascendens, Diplommatina quadrata, all Mousson, 1870. New species: Diancta aurea sp. n., Diancta aurita sp. n., Diancta basiplana sp. n., Diancta controversa sp. n., Diancta densecostulata sp. n., Diancta dextra sp. n., Diancta dilatata sp. n., Diancta distorta sp. n., Diancta pulchella sp. n., Diancta rotunda sp. n., Diancta subquadrata sp. n., Diancta trilamellata sp. n., Moussonia acuta sp. n., Moussonia barkeri sp. n., Moussonia brodieae sp. n., Moussonia longipalatalis sp. n., Moussonia minutissima sp. n., Moussonia obesa sp. n., Moussonia polita sp. n., Moussonia uncinata sp. n., Moussonia vitianoides sp. n., Palaina alberti sp. n., Palaina flammulata sp. n., Palaina glabella sp. n., Palaina kitteli sp. n., Palaina labeosa sp. n., Palaina parietalis sp. n., Palaina sulcata sp. n., Palaina truncata sp. n., Palaina tuberosissima sp. n.     

The rebound effect through industrial ecology’s eyes: a review of LCA-based studies

Purpose

Industrial ecology academics have embraced with great interest the rebound effect principle operationalised within energy economics. By pursuing more comprehensive assessments, they applied tools such as life cycle assessment (LCA) to appraise the environmental consequences of the rebound effect. As a result, the mainstream rebound mechanism was broadened and a diversity of (sometimes inconsistent) definitions and approaches unveiled. To depict the state of play, a comprehensive literature review is needed.

Methods

A literature review has been carried out by targeting scientific documents relevant for the integration of the rebound effect into LCA-based studies. The search was conducted using two approaches: (1) via online catalogues using a defined search criterion and (2) via cross-citation analysis from the documents identified through the first approach.

Results and discussion

By analysing a total of 42 works yielded during our review, it was possible to bring together the various advantages of the life cycle perspective, as well as to identify the main inconsistencies and uninformed claims present in literature. Concretely, three main advantages have been identified and are discussed: (1) the representation of the rebound effect as a multi-dimensional, life cycle estimate, (2) the improvement of the technology explicitness and (3) the broadening of the consumption and production factors leading to the rebound effect. Also, inconsistencies on the definition and classification of the rebound effect have been found among studies.

Conclusions

The review contributes a number of valuable insights to understand how the rebound effect has been treated within the industrial ecology and LCA fields. For instance, the conceptual and methodological refinements introduced by these fields represent a step forward from traditional viewpoints, making the study of the rebound effect more comprehensive and meaningful for environmental assessment and policy making. However, the broadened scope of this new approach unveiled some conceptual inconsistencies, which calls for a common framework. This framework would help the LCA community to consistently integrate the rebound effect as well as to create a common language with other disciplines, favouring learning and co-evolution. We believe that our findings can serve as a starting point in order to delineate such a common framework.     

The first record of genus Neocsikia Ôhira & Becker (Coleoptera,Elateridae, Dimini) in China,with the description of a new species

The click-beetle genus Neocsikia Ôhira & Becker, 1972 is newly recorded from Xizang, China upon the discoveries of Neocsikia nepalensis Ôhira & Becker, 1972 and N. xuhaoi Qiu, sp. nov. Neocsikia nepalensis is redescribed based on the type material from Nepal and material collected in Nyalam County, Xizang, China. Neocsikia xuhaoi Qiu, sp. nov. is described based on the material collected in Mêdog County, Xizang, China. Both species are illustrated and their principal diagnostic features are provided. A key to the species of Neocsikia is presented.https://www.zoobank.org/urn:lsid:zoobank.org:pub:1B7F59D5-02BC-4739-9B71-B560DA341FF3     

The “Balance of Nature”—Evolution of a Panchreston

The earliest concept of a balance of nature in Western thought saw it as being provided by gods but requiring human aid or encouragement for its maintenance. With the rise of Greek natural philosophy, emphasis shifted to traits gods endowed species with at the outset, rather than human actions, as key to maintaining the balance. The dominance of a constantly intervening God in the Middle Ages lessened interest in the inherent features of nature that would contribute to balance, but the Reformation led to renewed focus on such features, particularly traits of species that would maintain all of them but permit none to dominate nature. Darwin conceived of nature in balance, and his emphasis on competition and frequent tales of felicitous species interactions supported the idea of a balance of nature. But Darwin radically changed its underlying basis, from God to natural selection. Wallace was perhaps the first to challenge the very notion of a balance of nature as an undefined entity whose accuracy could not be tested. His skepticism was taken up again in the 20th century, culminating in a widespread rejection of the idea of a balance of nature by academic ecologists, who focus rather on a dynamic, often chaotic nature buffeted by constant disturbances. The balance-of-nature metaphor, however, lives on in large segments of the public, representing a fragile aspect of nature and biodiversity that it is our duty to protect.The notion of a “balance of nature” stretches back to early Greeks, who believed gods maintained it with the aid of human prayers, sacrifices, and rituals [1]. As Greek philosophers developed the idea of natural laws, human assistance in maintaining the balance did not disappear but was de-emphasized. Herodotus, for instance, the earliest known scholar to seek biological evidence for a balance of nature, asked how the different animal species each maintained their numbers, even though some species ate other species. Amassing facts and factoids, he saw divinely created predators'' reproductive rates lower than those of prey, buttressing the idea of a providentially determined balance with a tale of a mutualism between Nile crocodiles beset with leeches and a plover species that feeds on them [1]. Two myths in Plato''s Dialogues supported the idea of a balance of nature: the Timaeus myth, in which different elements of the universe, including living entities, are parts of a highly integrated “superorganism,” and the Protagoras myth, in which gods created each animal species with characteristics that would allow it to thrive and, having run out of biological traits, had to give man fire and superior intelligence [1]. Among Romans, Cicero followed Herodotus and Plato in advancing a balance of nature generated by different reproductive rates and traits among species, as well as interactions among species [1].The Middle Ages saw less interest in such pre-set devices as differential reproductive rates to keep nature in balance, perhaps because people believed in a God who would maintain the balance by frequent direct intervention [1]. The Reformation, however, fostered further development of the concept of a providential balance of nature set in motion at creation. Thomas Browne [2] added differential mortality rates to factors maintaining the balance, and Matthew Hale [3] proposed that lower rates of mortality for humans than for other animals maintain human dominance within a balanced nature and added vicissitudes of heat from the sun to the factors keeping any one species from getting out of hand.The discovery of fossils that could not be ascribed to known living species severely challenged the idea of a God-given balance of nature, as they contradicted the idea of species divinely created with the necessary features for survival [4]. John Ray [5] suggested that the living representatives of such fossils would be found in unexplored parts of the earth, a solution that was viable until the great scientific explorations of the late 18th and early 19th centuries [4]. Ray also argued that what would now be termed different Grinnellian ecological niches demonstrated God''s provision of each species with a space of its own in nature.According to Egerton [1], the earliest use of the term “balance” to refer specifically to ecology was probably by Ray''s disciple, William Derham [6], who asserted in 1714 that:

“The Balance of the Animal World is, throughout all Ages, kept even, and by a curious Harmony and just Proportion between the increase of all Animals, and the length of their Lives, the World is through all Ages well, but not over-stored.”

Derham recognized that human populations seemed to be endlessly increasing but saw this fact as a provision by God for future disasters. This explanation contrasts with that of Linnaeus [7], who saw human and other populations endlessly increasing but believed the size of the earth was also increasing to accommodate them. Derham grappled with the issue of theodicy but failed to reconcile plagues of noxious animals with the balance of nature, seeing them rather as “Rods and Scourges to chastise us, as means to excite our Wisdom, Care, and Industry” [1].Derham''s contemporary Richard Bradley [8],[9] focused more on biological facts and less on Providence in sketching a more comprehensive account of an ecological balance of nature, taking account of the rapidly expanding knowledge of biodiversity, noting that each plant had its phytophagous insects, each insect its parasitic wasps or flies and predatory birds, concluding that “all Bodies have some Dependence upon one another; and that every distinct Part of Nature''s Works is necessary for the Support of the rest; and that if any one was wanting, all the rest must consequently be out of Order.” Thus, he saw the balance as fragile rather than robust, in spite of a constantly intervening God. Linnaeus [10] similarly marshaled observations of species interactions to explain why no species increases to crowd out all others, adding competition to the predation, parasitism, and herbivory adduced by Bradley and also emphasizing the different roles (we might now say “niches”) of different species as allowing them all to coexist in a sort of superorganismic, balanced whole.Unlike Derham, Georges-Louis Leclerc, Comte de Buffon [11] managed to reconcile animal plagues with a balanced nature. He perceived the balance of nature as dynamic, with all species fluctuating between relative rarity and abundance, so that whenever a species became overabundant, weather, predation, and competition for food would bring it back into balance. Buffon''s successor as director of the Jardin des Plantes in Paris, Jacques-Henri Bernardin de Saint-Pierre [12], was probably the first to associate ecological damage caused by biological invasions with a disruption of the balance of nature. Observing damage to introduced trees from insects accidentally introduced with them, he argued that failure to introduce the birds that would eat the insects led to the damage. William Paley [13], perhaps the inspiration for today''s advocates of “intelligent design,” analogized nature to a watch. One would assume a smoothly running watch was designed with purpose, and so too nature was designed by God with balance and a purpose.In the 19th century, evolution burst on the scene, greatly influencing and ultimately modifying conceptions of a balance of nature. Fossils that seemed unrelated to any living species, as noted above, conflicted with the balance of nature, because they implied extinction, a manifestly unbalanced event that furthermore could be seen to imply that God had made a mistake. Whereas Ray had been able to argue that living exemplars of fossil species would be found in unexplored parts of the earth, by the 19th century, this explanation could be rejected. Jean-Baptiste Lamarck [14] resolved the conflict in a different way, arguing that species continually change, so the balance remains the same. The fossils thus represent ancestors of living species, not extinct lineages. Robert Chambers [15], another early evolutionist, similarly saw fossils not as a paradox in a balanced nature but as a consequence of the fact that, as the physical environment changed, species either evolved or went extinct.Alfred Russel Wallace was perhaps the first to question the very existence of a balance of nature, in a remarkable notebook entry, ca. 1855:

“Some species exclude all others in particular tracts. Where is the balance? When the locust devastates vast regions and causes the death of animals and man, what is the meaning of saying the balance is preserved… To human apprehension there is no balance but a struggle in which one often exterminates another” [16].

In modern parlance, Wallace appears almost to be asking how “balance” could be defined in such a way that a balance of nature could be a testable hypothesis.Darwin''s theory of evolution by natural selection certainly explained the existence of fossils, and his emphasis on inevitable competition both between and within species downplayed the role of niche specialization propounded by Plato, Cicero, Linnaeus, Derham, and others [1]. Darwin nevertheless saw the ecological roles of the diversity of species as parts of an almost superorganismic nature, and his main contribution to the idea of a balance of nature was his constant emphasis on competition and other mortality factors that kept all species'' populations in check [1]. His many metaphors and examples of the interactions among species, such as the tangled bank and the spinsters-cats-mice-bumblebees-clover stories in The Origin of Species [17], contributed to a sense of a highly balanced nature, but one driven by natural selection constantly changing species, rather than by God either intervening or creating species with traits that ensure their continued existence. Unlike Wallace, Darwin did not raise the issue of whether nature was actually balanced and how we would know if it was not.As ecology developed in the late 19th and early 20th centuries, it was inevitable that Wallace''s question—how to define “balance”—would be raised again and that increasingly wide and quantitative study, especially at the population level, would be brought to bear on the matter. The work of the early dominant plant ecologist Frederic Clements and his followers, with Clements'' notion of superorganismic communities [18], provided at least tacit support for the idea of a balance of nature, but his contemporary Charles Elton [19], a founder of the field of animal ecology and a leading student of animal population cycles, forcefully reprised Wallace''s concern:

“‘The balance of nature’ does not exist, and perhaps never has existed. The numbers of wild animals are constantly varying to a greater or lesser extent, and the variations are usually irregular in period and always irregular in amplitude. Each variation in the numbers of one species causes direct and indirect repercussions on the numbers of the others, and since many of the latter are themselves independently varying in numbers, the resultant confusion is remarkable.”

Despite Elton''s explicit skepticism, his depiction of energy flow through food chains and food webs was incorporated as a superorganismic analog to the physiology of individuals (e.g., [20]). Henry Gleason, another critic of the superorganism concept, who depicted populations distributed independently, rather than in highly organized communities, was ignored at this time [21].However, beginning with three papers in Ecological Monographs in 1947, the superorganism concept was increasingly questioned and, within 25 years, Gleason was vindicated and his views largely accepted by ecologists [22]. During this same period, extensive work by population biologists again took up Elton''s focus on population trajectories and contributed greatly to a growing recognition of the dynamism of nature and the fact that much of this dynamism did not seem regular or balanced [21]. The idea of a balanced nature did not immediately disappear among ecologists. For instance, a noteworthy book by C. B. Williams [23], Patterns in the Balance of Nature, described the distribution of abundances within communities or regions as evincing statistical regularity that might be construed as a type of “balance of nature,” at least if changes in individual populations do not change certain statistical features (a hypothesis that Williams considered untested at the time). But the predominant view by ecologists of the 1960s saw the whole notion of a balance as, at best, irrelevant and, at worst, a distraction. Ehrlich and Birch [24], for example, ridiculed the idea:

“The existence of supposed balance of nature is usually argued somewhat as follows. Species X has been in existence for thousands or perhaps millions of generations, and yet its numbers have never increased to infinity or decreased to zero. The same is true of the millions of other species still extant. During the next 100 years, the numbers of all these species will fluctuate; yet none will increase indefinitely, and only a few will become extinct… Such ‘observations’ are made the basis for the statement that population size is ‘controlled’ or ‘regulated,’ and that drastic changes in size are the results of upsetting the ‘balance of nature.’”

Another line of ecological research that became popular at the end of the 20th century was to equate “balance of nature” with some sort of equilibrium of numbers, usually of population sizes [25], but sometimes of species richness. The problem remained that, with numbers that vary for whatever reason, it is still arbitrary just how much temporal variation can be accommodated within a process or phenomenon for it still to be termed equilibrial [26]. Often the decision on whether to perceive an ecological process as equilibrial seems to be based on whether there is some sort of homeostatic regulation of the numbers, such as density-dependence, which A. J. Nicholson [27] suggested as an argument against Elton''s skepticism of the existence of a balance. The classic 1949 ecology text by Allee et al. [28] explicitly equated balance with equilibrium and cited various mechanisms, such as density-dependence, in support of its universality in nature [25]. Later similar sorts of mathematical arguments equated the mathematical stability of models representing nature with a balance of nature [29], although the increasing recognition of stochastic aspects and chaotic mathematics of population fluctuations made it more difficult to perceive a balanced nature in population trajectories [21].For academic ecologists, the notion of a balance of nature has become passé, and the term is widely recognized as a panchreston [30]—a term that means so many different things to different people that it is useless as a theoretical framework or explanatory device. Much recent research has been devoted to emphasizing the dynamic aspects of nature and prominence of natural or anthropogenic disturbances, particularly as evidenced by vicissitudes of population sizes, and advances the idea that there is no such thing as a long-term equilibrium (e.g., [31],[32]). Some authors explicitly relate this research to a rejection of the concept of a balance of nature (e.g., [33]–[35]), Pickett et al. [33] going so far as to say it must be replaced by a different metaphor, the “flux of nature.”The issue is confounded by the fact that the perception of balance can be sought at different levels (populations, communities, ecosystems) and spatial scales. Much of the earlier discussion of a balance was at the population and community levels—Browne, Hale, Bradley, Linnaeus, Buffon, Bernardin de Saint-Pierre, and Darwin saw balance in the limited fluctuations of populations and the interactions of populations as one force imposing the limits. The proponents of density-dependent population regulation fall in this category as well [36],[37]. As a balance is sought at the community and ecosystem levels, the sorts of evidence brought to bear on the matter become more complicated and abstract [37],[38]. It is increasingly difficult to imagine what sorts of empirical or observational data could test the notion of a balance. For instance, Williams''s balance of nature—evidenced by a particular statistical distribution of population sizes—would not be perceived as balanced by many observers in light of the fact that entire populations can crash, explode, or even go extinct within the constraint of a statistical distribution of a given shape. Early claims of a balance at the highest level, such as the various superorganisms (Plato''s Timaeus myth, Paley''s watch metaphor, Clements''s superorganismic plant community) can hardly be seen as anything other than metaphors rather than testable hypotheses and have fallen from favor. The most expansive conception of a balance of nature—the Gaia hypothesis [39]—has been almost universally rejected by scientists [40]. The advent and growing acceptance of the metapopulation concept of nature [41] also complicates the search for balance in bounded population fluctuations. Spatially limited individual populations can arise, fluctuate wildly, and even go extinct, while suitable dynamics maintain the widespread metapopulation as a whole.Yet, the idea of a balance of nature lives on in the popular imagination, especially among conservationists and environmentalists. However, the usual use of the metaphor in an environmental context suggests that the balance, whether given by God or produced by evolution, is a fragile balance, one that needs human actions for its maintenance. Through the 18th century, the balance of nature was probably primarily a comforting construct—it would protect us; it represented some sort of benign governance in the face of occasional awful events. When Darwin replaced God as the determinant of the balance with natural selection, the comfort of a balance of nature was not so overarching, if there was any comfort at all. Today, ecologists do not even recognize a balance, and those members of the public who do, see it as something we must protect if we are ever to reap benefits from it in the future (e.g., wetlands that might help ameliorate flooding from storms and sea-level rise). This shift is clear in the writings of Bill McKibben [42],[43], who talks frequently about balance, but about balance with nature, not balance of nature, and how humankind is headed towards a catastrophic future if it does not act promptly and radically to rebalance society with nature.     

Beobachtungen zur Lebensweise von Pycnogonum litorale (Ström) (Pantopoda)

Zusammenfassung Am Leitdamm des Jadebusens lebt Pycnogonum litorale im Lückensystem des Miesmuschelbesatzes. Dieser bietet mit hartem Untergrund, hoher Feuchtigkeit bei Niedrigwasser, genügend Actinien als Nahrung und guter Durchströmung bei gleichzeitigem Schutz vor Vertragung—offensichtlich günstige Lebensbedingungen für Pycnogonum litorale.Der Eiablage im Februar geht eine Reiterstellung des Männchens auf dem Weibchen von durchschnittlich 24 Tagen voraus. Unter künstlichen Kurztagbedingungen kann diese Reiterstellung auch außerhalb der Fortpflanzungsperiode eingenommen werden. Die Eier werden durch Rumpfbewegungen beider Partner zu den Ovigeren des Männchens bewegt. Bei 12°C schlüpfen die Larven etwa 41 bis 46 Tage nach der Eiablage aus, bei 19°C, im Sommer, schlüpften keine Larven.Im Jadebusen leben die Larven etwa 1/2 Jahn endoparasitisch in Hydrozoen. Die an die Metamorphose anschließende juvenile Phase, in der die Tiere frei leben, dauert ein knappes Jahr, die Reifehäutung erfolgt normalerweise im Sommer des zweiten Jahres, die Fortpflanzungsperiode etwa 6 Monate später, im Winter.

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Observations on the life biology of Pycnogonum litorale (Ström) (Pantopoda)

Summary Pycnogonum litorale lives in an interstitial system, of the mussel zone on the embankment of the Jadebusen. Hard substrate, high humidity at low tide, sufficient Metridium senile as food, and active currents together with protection from drifting, constitute favourable conditions for this pycnogonid.Prior to laying egg in February, the male remains in a riding position upon the female for approximately 24 days. Under artificial short-day conditions the riding position may also be assumed outside of the reproductive period. The eggs are transported to the ovigers of the male by trunk movements of both partners. At 12°C the larvae hatch about 41–46 days after egg-laying. No larvae hatched from eggs laid during summer at 19°C.The larvae live endoparasitically in Hydrozoa for about 1/2 year. Following metamorphosis, the freeliving juvenile phase lasts barely a year. The maturation moult normally takes place in the summer of the second year, the reproductive period beginning about 6 months later, in winter.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

The pepino(Solanum muricatum,Solanaceae): A “New” crop with a history

Pepino,Solanum muricatum, is an herbaceous subshrub that has long been grown in its native Andean South America. Pepino is usually cultivated for its edible fruits, but also has other economic uses. In spite of being a prominent crop in prehispanic times in the Andes, interest in pepino was cast into oblivion from some decades after the Spanish arrival to the present. Pepino etymology, prehispanic distribution, and postcolumbian dispersal are presented, with emphasis on outstanding historical aspects. Speculations on why the pepino has been neglected are also given. These include some features of pepino itself together with misconceptions. However, the pepino is today a species of increasing economic interest, and has a considerable potential for future exploitation.     

The repeat structure of two paralogous genes,Yersinia ruckeri invasin (yrInv) and a “Y. ruckeri invasin-like molecule”, (yrIlm) sheds light on the evolution of adhesive capacities of a fish pathogen

Inverse autotransporters comprise the recently identified type Ve secretion system and are exemplified by intimin from enterohaemorrhagic Escherichia coli and invasin from enteropathogenic Yersiniae. These proteins share a common domain architecture and promote bacterial adhesion to host cells. Here, we identified and characterized two putative inverse autotransporter genes in the fish pathogen Yersinia ruckeri NVH_3758, namely yrInv (for Y. ruckeri invasin) and yrIlm (for Y. ruckeri invasin-like molecule). When trying to clone the highly repetitive genes for structural and functional studies, we experienced problems in obtaining PCR products. PCR failures and the highly repetitive nature of inverse autotransporters prompted us to sequence the genome of Y. ruckeri NVH_3758 using PacBio sequencing, which produces some of the longest average read lengths available in the industry at this moment. According to our sequencing data, YrIlm is composed of 2603 amino acids (7812 bp) and has a molecular mass of 256.4 kDa. Based on the new genome information, we performed PCR analysis on four non-sequenced Y. ruckeri strains as well as the sequenced. Y. ruckeri type strain. We found that the genes are variably present in the strains, and that the length of yrIlm, when present, also varies. In addition, the length of the gene product for all strains, including the type strain, was much longer than expected based on deposited sequences. The internal repeats of the yrInv gene product are highly diverged, but represent the same bacterial immunoglobulin-like domains as in yrIlm. Using qRT-PCR, we found that yrIlm and yrInv are differentially expressed under conditions relevant for pathogenesis. In addition, we compared the genomic context of both genes in the newly sequenced Y. ruckeri strain to all available PacBio-sequenced Y. ruckeri genomes, and found indications of recent events of horizontal gene transfer. Taken together, this study demonstrates and highlights the power of Single Molecule Real-Time technology for sequencing highly repetitive proteins, and sheds light on the genetic events that gave rise to these highly repetitive genes in a commercially important fish pathogen.