Dynamic changes of protoplasmic volume and of fine structure during osmotic adaptation in the intertidal red alga Porphyra umbilicalis

Abstract Cells of Porphyra umbilicalis show a biphasic osmotic regulatory response. After transfer from 1 × into 3.5 × artificial seawater medium (osmotic upshock) the protoplasts shrink rapidly, then recover their original size within 3 h and continue to increase over the next 14 d. After retransfer from 3.5 × into 1 × medium (osmotic downshock) the protoplasts swell immediately and then adjust to the normal size in 1 x medium. Parallel to the shrinkage of the protoplasts after osmotic upshocks the plasmalemma at first gets a wavy surface which becomes smooth again during the following adaptation process. Immediately after osmotic upshock the vacuolar volume increases and it decreases drastically after osmotic downshock. After osmotic upshocks only small vacuoles are present at first. In adapted plants, however, the vacuolar system is mainly composed of large vacuoles. The volume of the protoplasm without the vacuoles is regulated osmotically. Parallel to the increase in the vacuolar volume after osmotic upshocks there is an increase in the number of intramembraneous particles on the PF-face of the tonoplast. This high value is reduced rapidly to the original number after osmotic downshock. The findings are discussed in relation to the function of the vacuoles as compartments of inorganic ion accumulation during osmotic adaptation.     

The Devonian nekton revolution

Klug, C., Kröger, B., Kiessling, W., Mullins, G.L., Servais, T., Frýda, J., Korn, D. & Turner, S. 2009: The Devonian nekton revolution. Lethaia, 10.1111/j.1502‐3931.2009.00206.x Traditional analyses of Early Phanerozoic marine diversity at the genus level show an explosive radiation of marine life until the Late Ordovician, followed by a phase of erratic decline continuing until the end of the Palaeozoic, whereas a more recent analysis extends the duration of this early radiation into the Devonian. This catch‐all approach hides an evolutionary and ecological key event long after the Ordovician radiation: the rapid occupation of the free water column by animals during the Devonian. Here, we explore the timing of the occupation of the water column in the Palaeozoic and test the hypothesis that ecological escalation led to fundamental evolutionary changes in the mid‐Palaeozoic marine water column. According to our analyses, demersal and nektonic modes of life were probably initially driven by competition in the diversity‐saturated benthic habitats together with the availability of abundant planktonic food. Escalatory feedback then promoted the rapid rise of nekton in the Devonian as suggested by the sequence and tempo of water‐column occupation. □Devonian, diversity, ecology, food webs, nekton, plankton, radiation.     

FIRST RECORD OF NILSSONIOPTERIS (GYMNOSPERMOPHYTA, BENNETTITALES) FROM THE CARNIAN (UPPER TRIASSIC) OF LUNZ, LOWER AUSTRIA

Abstract:  The Carnian (Late Triassic) flora of Lunz in Lower Austria is famous for an abundance of well-preserved bennettitalean and cycadalean foliage and reproductive structures. However, only the fertile remains have been studied in detail to date. Recently completed systematic macromorphological and cuticular analyses of leaf fossils from Lunz revealed that several forms previously accommodated in the genus Macrotaeniopteris do not represent ferns but rather Bennettitales assignable to the genus Nilssoniopteris . We describe three species of Nilssoniopteris , which represent the first records for this genus from Lunz, and one of the earliest accounts of Nilssoniopteris in the Northern Hemisphere. The following new combinations are introduced: Nilssoniopteris haidingeri (Stur ex Krasser, 1909 a ) comb. nov., N. angustior (Stur ex Krasser, 1909 a ) comb. nov. and N. lunzensis (Stur ex Krasser, 1909 a ) comb. nov. The discovery of Nilssoniopteris further substantiates the significance of the Lunz flora as one of the richest and most diverse early Late Triassic floras from the Northern Hemisphere.     

Genetic evidence of intercontinental movement of avian influenza in a migratory bird: the northern pintail (Anas acuta)

The role of migratory birds in the movement of the highly pathogenic (HP) avian influenza H5N1 remains a subject of debate. Testing hypotheses regarding intercontinental movement of low pathogenic avian influenza (LPAI) viruses will help evaluate the potential that wild birds could carry Asian-origin strains of HP avian influenza to North America during migration. Previous North American assessments of LPAI genetic variation have found few Asian reassortment events. Here, we present results from whole-genome analyses of LPAI isolates collected in Alaska from the northern pintail (Anas acuta), a species that migrates between North America and Asia. Phylogenetic analyses confirmed the genetic divergence between Asian and North American strains of LPAI, but also suggested inter-continental virus exchange and at a higher frequency than previously documented. In 38 isolates from Alaska, nearly half (44.7%) had at least one gene segment more closely related to Asian than to North American strains of LPAI. Additionally, sequences of several Asian LPAI isolates from GenBank clustered more closely with North American northern pintail isolates than with other Asian origin viruses. Our data support the role of wild birds in the intercontinental transfer of influenza viruses, and reveal a higher degree of transfer in Alaska than elsewhere in North America.     

Ormieresia carcini gen. n., sp. n., Microsporidie du Crabe Méditerranéan, Carcinus mediterraneus Czerniavsky, 1884: Cycle Évolutif et Étude Ultrastructurale

RÉSUMÉ. Une nouvelle microsporidie, Ormieresia carcini gen. n., sp. n., est trouvée dans Carcinus mediterraneus Czerniavsky, 1884. Son évolution et ses ultrastructures sont étudiees.
Le cycle débute par un méronte limité par une membrane unitaire et possédant un diplocaryon. Toute la sporogonie se déroule dans la musculature de l'höte. Les stades sporogoniaux sont enveloppés dans une membrane pansporoblastique persistante. Dans chaque pansporoblaste, la sporoblastogenése (donnant naissance à 8 sporoblastes) est particulière; un plasmode sporogonial octonucléé manque. Au cours des divisions schizogoniques et sporogoniques, chaque centre cinétique est formé de 2 plaques, une incluse dans l'enveloppe nucléaire, l'autre occupant une position extranucléaire. Les sporontes en division et les sporoblastes sécrètent des substances métaboliques (granules, tubes) qui sont déposées dans l'espace pansporoblastique.
La spore uninucléée est longue et cylindrique (19,1 × 2,4 μm). Un manubrium rectiligne traverse la spore. Son extrémité postérieure se rétrécit brusquement en un filament polaire décrlvant 4 ou 5 tours de spire. L'extrémité antérieure du manubrium est attachée au capuchon polaire lui-même comprimé par un double anneau. La partie antérieure du manubrium est entourée par un polaroplaste formé d'une zone spongieuse et d'une zone lamellaire.     

Spatial Variation in Lesser Prairie-Chicken Demography: A Sensitivity Analysis of Population Dynamics and Management Alternatives

ABSTRACT The lesser prairie-chicken (Tympanuchus pallidicinctus) is currently considered a candidate for protection under the Endangered Species Act. To identify potential limiting factors for lesser prairie-chicken populations, we developed an age-based matrix model of lesser prairie-chicken population dynamics to compare the relative importance of components of reproduction and survival, and determine if various management alternatives stabilize or increase rates of population change. We based our analyses on an intensive 6-year population study from which demographic rates were estimated for each age class in Kansas. We used deterministic models and elasticity values to identify parameters predicted to have the greatest effect on the rate of population change (λ) at 2 study sites. Last, we used life-stage simulation analysis to simulate various management alternatives. Lambda was <1 for both populations (site 1: λ = 0.54, site 2: λ = 0.74). However, we found differences in sensitivity to nest success and chick survival between populations. The results of the simulated management scenarios complemented the lower-level elasticity analysis and indicated the relative importance of female survival during the breeding season compared with winter. If management practices are only capable of targeting a single demographic rate, changes to either nest success or chick survival had the greatest impact on λ at site 1 and 2, respectively. Management that simultaneously manipulated both nest success and chick survival was predicted to have a greater effect on λ than changes in survival of adult females. In practice, our demographic analyses indicate that effective management should be based on habitat conservation measures to increase components of fecundity.     

Morphology and function of the head in foetal and juvenile Scolecomorphus kirkii (Amphibia: Gymnophiona: Scolecomorphidae)

The external and musculoskeletal morphology of the head is described for an ontogenetic series of the scolecomorphid caecilian Scolecomorphus kirkii . The rostral region of foetuses and juveniles is expanded into large, posterolaterally pointing paraoral processes that are formed by the maxilla. Extraoral teeth are present on the underside of the rostrum and laterally on the paraoral processes. In the foetuses, teeth are covered by epidermal tissue. The endoskeletal part of the foetal skull is largely cartilaginous, but all of the dermal bones, with the exception of the squamosal, are present. The foetal chondrocranium is extensively developed and shows a peculiar, posterolateral process of the nasal capsule that is connected to the trabecula cranii by a transverse bar posterior to the choana, and extends further posterior beyond the level of the posterior end of the pila antotica. Only two mm. adductor mandibulae are present, together with two pterygoideus muscles that insert onto the lower jaw. The palatoquadrate and quadrate of foetuses and juveniles, respectively, are highly mobile. It is suggested that the derived head morphology of Scolecomorphus foetuses and juveniles is an adaptation to specialized postparitive feeding.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 491–504.     

Oikozetetes from the early Cambrian of South Australia: implications for halkieriid affinities and functional morphology

Shells of Oikozetetes and isolated halkieriid sclerites from a section of the lower Cambrian Mernmerna Formation in the Flinders Ranges, South Australia, are tentatively considered as being derived from the same scleritome. Details of shell morphology and the possible combination of biomineralized shell and sclerites suggest that Oikozetetes , if interpreted correctly, is closely related to Halkieria . A new interpretation of Oikozetetes shell morphology, in addition to the first report of paired muscle scars on the interior surface, sheds new light on the possible functional morphology of halkieriid shells and the means of attaching the shell to the body. The occurrence of Oikozetetes in South Australia extends its biostratigraphic range to the lower Cambrian and biogeographic range to East Gondwana.