Identification and characterization of B"-subunits of protein phosphatase 2 A in Xenopus laevis oocytes and adult tissues.

Protein phosphatase 2A is a phosphoserine/threonine phosphatase implicated in many cellular processes. The core enzyme comprises a catalytic and a PR65/A-subunit. The substrate specificity and subcellular localization are determined by a third regulatory B-subunit (PR55/B, PR61/B' and PR72/130/B"). To identify the proteins of the B" family in Xenopus laevis oocytes, a prophase Xenopus oocyte cDNA library was screened using human PR130 cDNA as a probe. Three different classes of cDNAs were isolated. One class is very similar to human PR130 and is probably the Xenopus orthologue of PR130 (XPR130). A second class of clones (XN73) is identical to the N-terminal part of XPR130 but ends a few amino acids downstream of the putative splicing site of PR130. To investigate how this occurs, the genomic structure of the human PR130 gene was determined. This novel protein does not act as a PP2A subunit but might compete with the function of PR130. The third set of clones (XPR70) is very similar to human PR48 but has an N-terminal extension. Further analysis of the human EST-database and the human PR48 gene structure, revealed that the human PR48 clone published is incomplete. The Xenopus orthologue of PR48 encodes a protein of 70 kDa which like the XPR130, interacts with the A-subunit in GST pull-down assays. XPR70 is ubiquitously expressed in adult tissues and oocytes whereas expression of XPR130 is very low in brain and oocytes. Expression of XN73 mainly parallels XPR130 with the exception of the brain.     

Phylogeography of a Palaearctic sedentary passerine,the willow tit (Parus montanus)

We analysed variation of the mitochondrial control region from willow tits through its Palaearctic distribution range. Although we found high amount of genetic variation (π=1.114%), there was almost no differentiation between subspecies or geographical localities. This may be because of a combination of several ecological and genetic factors, including a relatively homogenic habitat through the distribution range, lack of geographical barriers, high gene flow and a large long‐term effective population size. On the contrary, in the songar tit, which is sometimes considered to be conspecific with the willow tit, the mitochondrial lineages seem to correlate with the geographical locality and are clearly distinct from the willow tit. We concluded that the common ancestors of willow and songar tits existed some 1.5–2 Myr ago in the south‐eastern Asia. After the last Ice Ages, the willow tit expanded all through the Palaearctic, whereas the songar tit remained in eastern Asia.     

Akustische Differenzierung verwandtschaftlicher Beziehungen in derParus (Periparus)-Gruppe nach Untersuchungen im Nepal-Himalaya

Zusammenfassung Die fünf Formen der UntergattungParus (Periparus) des südlichen Zentral-Asien(rufonuchalis, rubidiventris, beavani, melanolophus, aemodius) werden morphologisch, biologisch-ökologisch und vor allem akustisch differenziert. Die Spezifität der Gesänge gilt als wesentliches Art-Kriterium; sie wird mit Attrappen-Versuchen getestet.1.Rufonuchalis, rubidiventris undbeavani (Fichtenmeisen-Gruppe) bilden im Nepal-Himalaya Arealgrenzen aus.Rufonuchalis undrubidiventris leben dort sympatrisch,rubidiventris undbeavani allopatrisch ohne Introgressionszone. Rubidiventris undbeavani haben übereinstimmende ökologische Ansprüche;rufonuchalis als größere und trockenadaptierte Form weicht merklich ab. Die Arealgrenzen vonrufonuchalis undrubidiventris sind im westlichen Nepal-Himalaya klimatisch bedingt (Monsun!), nicht durch Konkurrenz mit anderenPeriparus-Formen.Reviergesänge der farblich fast ununterscheidbarenrufonuchalis undbeavani divergieren sehr, die vonrubidiventris undbeavani sind gleich. Rufonuchalis verfügt über 2 Gesangstypen: Trillergesang dient der Reviermarkierung, Pfiffgesang der Revierverteidigung. Beide Gesangsformen entsprechen nicht demParus-Gesangsschema, wohl aber der Klappergesang vonrubidiventris undbeavani. Beavani reagiert im Attrappen-Test nur auf denrufonuchalis-Pfiffgesang und besitzt vergleichbare Lautäußerungen.Rufonuchalis-Trillergesang findet beibeavani ebenfalls Entsprechungen, jedoch nicht beirubidiventris.Spezialisierte Trillergesang-Elemente vonrufonuchalis undbeavani werden als homolog betrachtet. Bei diesen allopatrischen Formen konnten sie erhalten bleiben, der mitrufonuchalis sympatrischerubidiventris hat sie reduziert.Die gleichfarbigenrufonuchalis undbeavani haben das Himalaya-System nie kontinuierlich besiedelt; ihre Areale standen ursprünglich über die Waldzonen Zentralasiens miteinander in Verbindung.Akustische Analyse und Verbreitungsmuster weisenrufonuchalis undrubidiventris (mit den Subspeziesrubidiventris undbeavani) als eigene Spezies aus; sie werden zu einer Superspezies verklammert.2. Die Areale vonP. ater aemodius undP. melanolophus stehen im zentralen Himalaya in sekundärem Kontakt; sie bilden dort eine Hybrid-(Introgressions-)Zone von 70 km Breite.An keiner Stelle desaemodius- bzw.melanolophus-Areals kommen die beiden Ausgangsformen bzw. Hybriden und Ausgangsformen nebeneinander vor. Merkliche Zuwanderung in das Hybridgebiet aus östlichen oder westlichen Arealteilen findet nicht statt.Es existieren Hybriden, die nicht intermediär zwischen den Ausgangsformen stehen, sondern von ihnen in Farbmuster und Färbung markant abweichen (rostbäuchige Hybriden).Vom Gebiet reineraemodius-Phäne zu dem reinermelanolophus-Phäne verläuft eine Merkmalsprogression:aemodius-Beige der Unterseite zu Rostrot;aemodius-Beige der Flanken zumelanolophus-Grau. Rostrot der Unterseite schlägt fast ohne Übergang zumelanolophus-Grau um (bisher nur für eine Population belegt).Alle Populationen des Hybridgürtels sind voll fortpflanzungsfähig (Reviergesang, Revierabgrenzung, -Brutfleck, -Gonadenentwicklung). Die Ausgangsformen haben (noch) keine verschiedenen adaptiven Niveaus erreicht; die Hybriden sind bei der Paarbildung (offensichtlich) nicht unterlegen.Isolationsmechanismen zwischen Ausgangsformen und Hybriden sind (heute) nicht (mehr) entwickelt; füraemodius undmelanolophus werden gering entwickelte akustische (und optische) postuliert (Hinweise durch Hybridisation in Gefangenschaft).Rostfarbigkeit wird als altes Merkmal derPeriparus-Gruppe angesehen, sein Auftreten bei den Hybriden als Atavismus.Reviergesänge aus derater/melanolophus-Gruppe sind einander sehr ähnlich. Der Gesang mitteleuropäischera. ater und der vonmelanolophus zeichnet sich durch ansteigende Elemente aus, diea. aemodius fehlen. Auf solche Gesangstypen reagiertaemodius nur mangelhaft.Die Gesänge in den Hybridpopulationen gleichen jenen vonaemodius; das wird auf Lernen desaemodius-Repertoires der Hybriden während des ersten Kontaktes vonmelanolophus undaemodius zurückgeführt.Süddeutschea. ater reagieren nur zur Zeit höchster Revierverteidigungs-Bereitschaft auf einen bestimmtenaemodius-Strophentyp. Auf diesen Strophentyp reagierten auch syntop lebendeP. major; er enthält Merkmale der Gesänge beider Arten.Die genetische Divergenz vonaemodius undmelanolophus — kenntlich an den rostbäuchigen Hybriden — legt nahe, den Artstatus beider bedingt aufrechtzuerhalten: SuperspeziesP. ater mit den SemispeziesP. ater undP. melanolophus.

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Acoustic differentiation of phylogenetic relations in theParus (Periparus) group from investigations in the Nepal Himalayas

Summary In the Nepal Himalayas 5 taxa of the subgenusParus (Periparus) exist — the greatest concentration of this subgenus in the whole Palearctic region. The taxa belong to 2 groups: 1.rufonuchalis, rubidiventris, beavani; 2. aemodius, melanolophus (fig. 1). All forms settle in the same altitude belt from about 2800 to 4200 m — three of them even in the same locality.Rufonuchalis is adapted to dry habitats mainly of West Central Asia and is thus restricted in Nepal to the Western parts (fig. 3, 4).The up to now unclarified status of all forms is determined as follows: Distinct species areP. rufonuchalis andP. rubidiventris (with highly different subspeciesP. r. rubidiventris andP. r. beavani) and they are regarded as a superspecies.P. rufonuchalis andP. r. rubidiventris live syntopically in West Nepal and display different territorial songs.Both differ remarkably in body size and bill size. Certain acoustic similarities indicating close relationship could be shown betweenrufonuchalis and the allopatric (fig. 3, 4)rubidiventris beavani; r. beavani reacts to the playback of whistle song (Pfiffgesang, fig. 10) ofP. rufonuchalis (see also fig. 14).The areas ofP. r. rubidiventris andP. r. beavani are separated apparently only by the Bhote Kosi river in East Nepal (fig. 4). Introgression is not (yet) known; the songs are identical (fig. 8). P. melanolophus andP. ater aemodius hybridize in West Nepal in a zone of secondary contact. Their areas are linked by a zone of introgression (fig. 17, 18). In that zone cinnamomeous bellied hybrids locally occur differing thus strikingly in colour from both parental species (fig. 1). Sympatric occurrence ofmelanolophus andater aemodius is not known and is not expected either.Territorial songs ofa. aemodius (fig. 21) andmelanolophus (fig. 25) are very similar and both species obviously do not differ in their ecology. Despite the small introgression belt, similar songs and apparently very similar or even identical adaptive peaks,P. ater andP. melanolophus are still treated as distinct species but reduced to semispecies level. In doing so the genetic divergence betweenater aemodius andmelanolophus indicated by the cinnamomeous bellied hybrids is emphasized.

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Mit einem Jahresstipendium des Deutschen Akademischen Austauschdienstes und einer Sachbeihilfe der Deutschen Forschungsgemeinschaft. — Ergebnisse der Nepal-Reisen 1969/70, 1973 und 1974, Nr. 36. — Nr. 35: Senckenbergiana biol., 56 (4/6): 247–256, 1975.     

The Potential for pathogenicity was present in the ancestor of the Ascomycete subphylum Pezizomycotina

Background  

Previous studies in Ascomycetes have shown that the function of gene families of which the size is considerably larger in extant pathogens than in non-pathogens could be related to pathogenicity traits. However, by only comparing gene inventories in extant species, no insights can be gained into the evolutionary process that gave rise to these larger family sizes in pathogens. Moreover, most studies which consider gene families in extant species only tend to explain observed differences in gene family sizes by gains rather than by losses, hereby largely underestimating the impact of gene loss during genome evolution.     

Effect of low inoculation density in the scale-up of insect cell cultures

The scale-up of insect cell cultures and the production of baculovirus with these cultures is dependent on the inoculation density applied. The effect of applying a low inoculation on the specific growth rate and on the duration of the lag phase was tested. Three different cell lines, HzAm1, Ha2302, and Sf21 were tested in a total of five cell line/medium combinations. Growth in suspension culture was examined, and data obtained were fitted with the Gompertz equation. A significant decline in specific growth rate with decreasing inoculation density was observed in all cell line/medium combinations, except for HzAm1. No critical inoculation density, below which no growth would occur, was found. In suspension culture in shake flasks, an inoculation density of 5 x 10(4) cells/mL is achievable, without severely influencing the overall growth rate. A lower inoculation density in suspension culture results in less steps in the scale-up process and might be a tool in bypassing the viral passage effect.     

Coordinate induction of PPAR alpha and SREBP2 in multifunctional protein 2 deficient mice

Mice with inactivation of the D-specific multifunctional protein 2 (MFP2), a crucial enzyme of peroxisomal beta-oxidation, develop multiple pathologies in diverse tissues already starting in the postnatal period. Gene expression profiling performed on liver of 2-day-old pups revealed up-regulation of PPAR alpha responsive genes in knockout mice. Surprisingly, also genes involved in cholesterol biosynthesis were markedly induced. Real-time PCR confirmed the induction of PPAR alpha target genes and of HMGCR and SREBP2, both involved in cholesterol synthesis, in lactating and in adult MFP2 knockout mice. In accordance, the rate of cholesterol biosynthesis was significantly increased in liver of knockout mice but the hepatic cholesterol concentration was unaltered. In MFP2/PPAR alpha double knockout mice, up-regulations of SREBP2 and HMGCR were markedly attenuated. These data demonstrate a tight interrelationship between induction of PPAR alpha by endogenous ligands and up-regulation of genes of cholesterol biosynthesis through increased expression of SREBP2.