Chloroplast DNA variation in the shrub Justicia areysiana (Acanthaceae) endemic to the monsoon affected coastal mountains of the southern Arabian Peninsula

The monsoon affected mountains of the southern Arabian Peninsula harbour in climatically favoured refugia vegetation elements of palaeo-African origin. To understand better the temporal and spatial differentiation of these refugia, chloroplast variation in Justicia areysiana Deflers (Acanthaceae), a shrub species endemic to the Yemeni and Omani mountains close to the Arabian Sea, was studied using PCR-RFLP and chloroplast microsatellite diversity. Eleven haplotypes were characterized and show a distinct geographical distribution pattern with a deep split between populations from south Yemeni fog oases and those from Hawf Mountains/Dhofar region in east Yemen and south Oman. Very limited haplotype diversity within populations (h_S = 0.15) and a high level of population differentiation (G_ST = 0.81) demonstrate the strong genetic isolation of populations from each other. Past oscillations between humid and arid periods connected with glacial and interglacial episodes in the Pleistocene and Holocene are considered responsible for the observed patterns of genetic variation.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 148 , 437–444.     

Analysis of the mitochondrial genome of Schistocerca gregaria gregaria (Orthoptera: Acrididae)

In the present study, we present the full sequence of the mitochondrial genome of the African desert locust Schistocerca gregaria gregaria. The size of 15625 bp reported matches very well with mitochondrial genomes of other Orthopteriodea. The mitochondrial genome comprises 13 protein‐coding genes, two ribosomal RNAs and 22 t‐RNAs with two t‐RNA (trnD and trnK) rearrangements that are typical for the taxon Caelifera. We compared the sequence with 12 mitochondrial genes of Schistocerca gregaria flaviventris and Schistocerca americana and used some of these data to construct phylogenetic trees, which confirm the close relationship between the two subspecies S. g. flaviventris and S. g. gregaria. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 296–305.     

Dinoflagellate cyst biostratigraphy of the Opalinuston Formation (Middle Jurassic) in the Aalenian type area in southwest Germany and north Switzerland

Feist‐Burkhardt, S. & Pross, J. 2010: Dinoflagellate cyst biostratigraphy of the Opalinuston Formation (Middle Jurassic) in the Aalenian type area in southwest Germany and north Switzerland. Lethaia, Vol. 43, pp. 10–31. In order to provide a detailed dinoflagellate cyst stratigraphy of the Lower Aalenian Opalinuston Formation from the Aalenian type area, 68 samples from four boreholes and one outcrop section were analysed. The sample localities are Hausen an der Fils and Wittnau in southwest Germany, Weiach in north Switzerland and Mont Russelin in the Swiss Jura Mountains. Dinoflagellate cyst assemblages were recovered from the Late Toarcian Aalensis Zone to the Late Aalenian Murchisonae Zone. The samples yielded rich, well‐preserved and diverse assemblages with 51 dinoflagellate cyst taxa identified in total. The dinoflagellate cyst distribution data obtained from this study allow a high‐resolution biostratigraphical subdivision of the lowermost Middle Jurassic Opalinuston Formation into four palynostratigraphical units. First and last occurrences, acmes and consistent presence of the species Batiacasphaera sp. A, Evansia cf. granochagrinata, Kallosphaeridium praussii, Nannoceratopsis triangulata, Phallocysta? frommernensis and Wallodinium laganum were selected as the criteria for defining these units. The obtained high‐resolution palynostratigraphical scheme provides a basis for establishing and further refining early Middle Jurassic biostratigraphy in the Boreal and Tethyan realms. □Aalenian, biostratigraphy, dinoflagellate cysts, Germany, Jurassic, Switzerland, Toarcian.     

What to do in marine biotechnology?

During the symposium "Marine Biotechnology: Basics and Applications", held 25 February-1 March, 2003 in Matalasca?as, Spain, a special brainstorm session was organized. Two questions were addressed: 1, "What is the most desirable development in marine biotechnology"?; 2, "What is the most spectacular development in this field in your 'wildest' dreams"? The outcome of this session is reported in this paper. From the more than 250 ideas generated, concern for the environment and human health emerged as the most significant issues.     

Vergleichende Untersuchungen zum Kontaktverhalten verschiedener Arten der Gattung Tilapia (Cichlidae,Pisces) und ihrer Bastarde

• 1 Tilapia tholloni (Substratbrüter), T. nilotica (weiblicher Maulbrüter) und T. heudeloti macrocephala (männlicher Maulbrüter) wurden künstlich erbrütet und ihre angeborenen Kontaktreaktionen in standardisierten Attrappenversuchen untersucht.
• 2 Das Kontaktverhalten muß während einer kritischen Phase (bei T. nilotica unter den angegebenen Versuchsbedingungen bis ungefähr zum 21. Tag nach dem Ablaichen) aktiviert werden, wenn es längere Zeit andauern soll (= Reaktionsphase). Die Reaktionsphase kann bei T. nilotica mehrere Wochen dauern. In ihr nimmt die Reaktionsstärke (Anzahl und Dauer der Kontakte) zunächst rasch zu, erreicht ein Maximum und nimmt dann allmählich wieder ab. Anstieg, Maximum und Abnahme sind an bestimmte Entwicklungsabschnitte gebunden, weitgehend unabhängig davon, ob die Tiere zuvor schon Kontaktverhalten geäußert haben oder nicht. Die Kontaktreaktionen unterscheiden sich u. a. durch die Dauer der Kontakte: tholloni = 0,7 Sek., nilotica = 86,5 Sek., heudeloti m. = 1,5 Sek. je Tag und Tier (Maximalwerte bei bestimmten, für alle Arten gleichen Versuchsbedingungen).
• 3 Von der Aufzuchttemperatur hängt es ab, in welchem Entwicklungsabschnitt die Reaktionsphase liegt. Das Reaktionsmaximum junger T. nilotica lag bei 24° C am 9., bei 29° C am Tag nach der Eiablage.
• 4 Geblendete nilotica-Jungfische zeigten nur zu Beginn der Reaktionsphase schwaches Kontaktverhalten, normale Tiere äußerten gegenüber einer durchsichtigen Glasattrappe abgeschwächtes, nur kurze Zeit dauerndes Kontaktverhalten. Das Kontaktverhalten wird durch mechanische (Strömung) und optische Reize ausgelöter und gesteuert.
• 5 Junge Maulbrüter aus kleinen Eiern erreichten eine längere Kontaktdauer als solche aus größeren. Nach künstlicher Reduktion der Dottermenge um 10–20%) erhöhte sich die Kontaktdauer bei jungen nilotica um 23,1%, die Zahl der Kontakte nahm gleichzeitig um 7,6% ab. Die ♀♀ der substratbrütenden T. mariae legen große Eier, die Jungen zeigten gegenüber Attrappen intensive Kontaktreaktionen. Es wird die Frage diskutiert, ob das Erreichen einer bestimmten Eigröße eine Voraussetzung für das Entstehen des Kontaktverhaltens gewesen sein könnte.
• 6 Die Kurzkontakte junger T. tholloni werden aus ihrer Orientierungsreaktion abgeleitet und als Vorstufe des Kontaktverhaltens gedeutet.
• 7 7. Mehrere Tilapia-Arten wurden künstlich gekreuzt. Bei Verwendung von tholloni-Sperma wiesen die Bastarde eine erhöhte Sterblichkeit auf. Aus der Kreuzung T. tholloni ♀ ～ T. nilotica ♂ (Substratbrüter ～ weiblicher Maulbrüter) gingen nur ♀♀ hervor. Die Kreuzung T. heudeloti macrocephala ～ T. nilotica (männlicher ～ weiblicher Maulbrüter) erbrachte fertile F₁- und F₂-Generationen sowie alle vier möglichen Rückkreuzungen. Bei der Vererbung des Kontaktverhaltens (gemessen an der Dauer der Kontakte) scheinen relativ wenig Erbfaktoren mitzuwirken, T. heudeloti m. erwies sich gegenüber nilotica als praevalent. Ein Teil der Bastarde aus der Kreuzung T. tholloni ♀ ～ T. nilotica ♂ (F₁) (Substratbrüter ～ weiblicher Maulbrüter) lag auf der Merkmalsskala zwischen den Ausgangsarten, der Rest verteilte sich sowohl auf den Bereich von tholloni als auch auf den Bereich von nilotica.

     

Mike, a chimeric filamentous phage designed for the separate production of either DNA strand of pKUN vector plasmids by F+ cells

To enable the separate production of either DNA strand of recombinant pKUN plasmids [Peeters et al., Gene 41 (1986) 39-46] by conjugation-deficient F+ cells a chimeric Ff/IKe filamentous phage, Mike, has been constructed. Its genome contains the functions required for asymmetric DNA replication from the N-plasmid specific filamentous phage IKe, and the functions required for host cell penetration, single-stranded DNA accumulation, phage assembly, and secretion from the F-plasmid specific filamentous phage Ff (i.e. M13, fl, or fd).     

Modeling brewers' yeast flocculation

Flocculation of yeast cells occurs during the fermentation of beer. Partway through the fermentation the cells become flocculent and start to form flocs. If the environmental conditions, such as medium composition and fluid velocities in the tank, are optimal, the flocs will grow in size large enough to settle. After settling of the main part of the yeast the green beer is left, containing only a small amount of yeast necessary for rest conversions during the next process step, the lagering. The physical process of flocculation is a dynamic equilibrium of floc formation and floc breakup resulting in a bimodal size distribution containing single cells and flocs. The floc size distribution and the single cell amount were measured under the different conditions that occur during full scale fermentation. Influences on flocculation such as floc strength, specific power input, and total number of yeast cells in suspension were studied. A flocculation model was developed, and the measured data used for validation. Yeast floc formation can be described with the collision theory assuming a constant collision efficiency. The breakup of flocs appears to occur mainly via two mechanisms, the splitting of flocs and the erosion of yeast cells from the floc surface. The splitting rate determines the average floc size and the erosion rate determines the number of single cells. Regarding the size of the flocs with respect to the scale of turbulence, only the viscous subrange needs to be considered. With the model, the floc size distribution and the number of single cells can be predicted at a certain point during the fermentation. For this, the bond strength between the cells, the fractal dimension of the yeast, the specific power input in the tank and the number of yeast cells that are in suspension in the tank have to be known. Copyright 1998 John Wiley & Sons, Inc.     

Characterization of novel microsatellite loci for red clover (Trifolium pratense L.) from enriched genomic libraries

Twenty‐seven polymorphic microsatellite markers were isolated from red clover (Trifolium pratense). Allelic variability and cross‐species amplification were assessed on 24 red clover and eight white clover (Trifolium repens) genotypes. The number of alleles detected in red clover ranged from two to 25. Observed and expected heterozygosities were high with average values of 0.71 and 0.88, respectively. Five of the 27 loci were also successfully amplified from white clover, where two to 13 alleles were detected. These highly polymorphic microsatellite loci provide powerful tools for population genetic studies as well as for marker‐assisted selection in this important forage legume species.