Quantitation of gibberellins and the metabolism of [3H]gibberellin A1 during somatic embryogenesis in carrot and anise cell cultures

In a carrot (Daucus carota L.) cell line lacking the ability to undergo somatic embryogenasis, and in carrot and anise (Pimpinella anisum L.) cell lines in which embryogenesis could be regulated by presence or absence of 2,4-dichlorophen-oxyacetic acid (2,4-D), in the medium (+2,4-D=no embryogenesis,-2,4-D=embryo differentiation and development), the levels of endogenous gibberellin(s) (GA) were determined by the dwarfrice bioassay, and the metabolism of [³H]GA₁ was followed. Embryos harvested after 14 d of subculture in-2,4-D had low levels (0.2–0.3 g g^-1 dry weight) of polar GA (e.g. GA₁-like), but much (3–22 times) higher levels of less-polar GA (GA_4/7-like); GA₁, GA₄ and GA₇ are native to these cultures. Conversely, the undifferentiated cells in a non-embryogenic strain, and proembryos of an embryogenic strain (+2,4-D) showed very high levels of polar GA (2.9–4.4 g g^-1), and somewhat reduced levels of less-polar GA. Cultures of anise undergoing somatic embryo development (-2,4-D) metabolized [³H]GA₁ very quickly, whereas proembryo cultures of anise (+2,4-D) metabolized [³H]GA₁ slowly. The major metabolites of [³H]GA₁ in anise were tentatively identified as GA₈-glucoside (24%), GA₈ (15%), GA₁-glucoside (8%) and the ¹⁽¹⁰⁾GA₁-counterpart (2%). Thus, high levels of a GA₁-like substance and a reduced ability to metabolize GA₁ are correlated with the absence of embryo development, while lowered levels of GA₁-like substance and a rapid metabolism of GA₁ into GA₈ and GA-conjugates are correlated with continued embryo development. Exogenous application of GA₃ is known to reduce somatic embryogenesis in carrot cultures; GA₄ was found to have the same effect in anise cultures. Thus, a role (albeit negative) in somatic embryogenesis for a polar, biologically active GA is implied.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - GA gibberellin(s) or gibberellin-like substances - GC-RC gas chromatography-radiochromatogram counting - HPLC high-presare liquid chromatography - Rt retention time - TLC thinlaver chromatography     

No evidence of mineralization abnormalities in iliac bone of premenopausal women with type 2 diabetes mellitus

Objectives:Patients with type-2 diabetes mellitus (T2DM) have increased risk for bone fractures which points towards impaired bone quality.Methods:We measured bone mineralization density distribution (BMDD) and osteocyte lacunae section (OLS) characteristics based on quantitative backscattered electron images of transiliac biopsy samples from n=26 premenopausal women with T2DM. Outcomes were compared to those from reference cohorts as well as between T2DM subgroups defined by clinical characteristics.Results:Comparison to references did not reveal any differences in BMDD (all p>0.05) but a lowered OLS-density in cancellous bone in T2DM (-14.9%, p<0.001). Neither BMDD nor OLS-characteristics differed in T2DM subgroups defined by HbA1c (<7% versus >7%). The average degree of bone mineralization (CaMean) was higher (0.44 wt%Ca in T2DM, 0.30 wt%Ca in reference) and consistently the calcium concentration between the tetracycline double labels (CaYoung) was higher (0.76 wt%Ca, all p<0.001) in cancellous versus cortical bone.Conclusions:Our findings suggest that bone matrix mineralization was neither affected by the presence nor by the glycemic control of T2DM in our study cohort. The intra-individual differences between cancellous and cortical bone mineralization gave evidence for differences in the time course of the early mineralization process in these compartments in general.     

Selecting normalization genes for small diagnostic microarrays

Background  

Normalization of gene expression microarrays carrying thousands of genes is based on assumptions that do not hold for diagnostic microarrays carrying only few genes. Thus, applying standard microarray normalization strategies to diagnostic microarrays causes new normalization problems.     

Mapping the navigational knowledge of individually foraging ants,Myrmecia croslandi

Ants are efficient navigators, guided by path integration and visual landmarks. Path integration is the primary strategy in landmark-poor habitats, but landmarks are readily used when available. The landmark panorama provides reliable information about heading direction, routes and specific location. Visual memories for guidance are often acquired along routes or near to significant places. Over what area can such locally acquired memories provide information for reaching a place? This question is unusually approachable in the solitary foraging Australian jack jumper ant, since individual foragers typically travel to one or two nest-specific foraging trees. We find that within 10 m from the nest, ants both with and without home vector information available from path integration return directly to the nest from all compass directions, after briefly scanning the panorama. By reconstructing panoramic views within the successful homing range, we show that in the open woodland habitat of these ants, snapshot memories acquired close to the nest provide sufficient navigational information to determine nest-directed heading direction over a surprisingly large area, including areas that animals may have not visited previously.     

Vorkommen des Auerhuhns (Tetrao urogallus major C. L. Brehm, 1831) am Athos (Greichenland)

Summary At the Mount Athos the Capercaillie is spread in the montane high forests at an altitude between 1140 m and 1340 m above sea level. This isolated occurrence at the southern boundary of the species area and 140 km to the south of the breeding place in the Rhodope Mountains is the southernmost occurrence recorded so far. In former times, the Capercaillie presumably was widespread in the mountain forests of Central and Northern Greece.     

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.     

Broadening the genetic base of European maize heterotic pools with US Cornbelt germplasm using field and molecular marker data

Maize (Zea mays L.) breeders are concerned about the narrowing of the genetic base of elite germplasm. To reverse this trend, elite germplasm from other geographic regions can be introgressed, but due to lack of adaptation it is difficult to assess their breeding potential in the targeted environment. The objectives of this study were to (1) investigate the relationship between European and US maize germplasm, (2) examine the suitability of different mega-environments and measures of performance to assess the breeding potential of exotics, and (3) study the relationship of genetic distance with mid-parent heterosis (MPH). Eight European inbreds from the Dent and Flint heterotic groups, 11 US inbreds belonging to Stiff Stalk (SS), non-Stiff Stalk (NSS), and CIMMYT Pool 41, and their 88 factorial crosses in F₁ and F₂ generations were evaluated for grain yield and dry matter concentration. The experiments were conducted in three mega-environments: Central Europe (target mega-environment), US Cornbelt (mega-environment where donor lines were developed), and Southeast Europe (an intermediate mega-environment). The inbreds were also fingerprinted with 266 SSR markers. Suitable criteria to identify promising exotic germplasm were F₁ hybrid performance in the targeted mega-environment and F₁ and parental performance in the intermediate mega-environment. Marker-based genetic distances reflected relatedness among the inbreds, but showed no association with MPH. Based on genetic distance, MPH, and F₁ performance, we suggest to introgress SS germplasm into European Dents and NSS into European Flints, in order to exploit the specific adaptation of European flint germplasm and the excellent combining ability of US germplasm in European maize breeding programs.     

Calcium dysregulation in Alzheimer's disease

Alzheimer disease (AD) is the most common form of adult dementia. Its pathological hallmarks are synaptic degeneration, deposition of amyloid plaques and neurofibrillary tangles, leading to neuronal loss. A few hypotheses have been proposed to explain AD pathogenesis. The beta-amyloid (Abeta) and hyperphosphorylated tau hypotheses suggest that these proteins are the main players in AD development. Another hypothesis proposes that the dysregulation of calcium homeostasis may be a key factor in accelerating other pathological changes. Although Abeta and tau have been extensively studied, recently published data provide a growing body of evidence supporting the critical role of calcium signalling in AD. For example, presenilins, which are mutated in familial cases of AD, were demonstrated to form low conductance calcium channels in the ER and elevated cytosolic calcium concentration increases amyloid generation. Moreover, memantine, an antagonist of the NMDA-calcium channel receptor, has been found to have a beneficial effect for AD patients offering novel possibilities for a calcium signalling targeted therapy of AD. This review underscores the growing importance of calcium ions in AD development and focuses on the relevant aspects of calcium homeostasis.     

Diffusion is capable of translating anisotropic apoptosis initiation into a homogeneous execution of cell death

Background  

Apoptosis is an essential cell death process throughout the entire life span of all metazoans and its deregulation in humans has been implicated in many proliferative and degenerative diseases. Mitochondrial outer membrane permeabilisation (MOMP) and activation of effector caspases are key processes during apoptosis signalling. MOMP can be subject to spatial coordination in human cancer cells, resulting in intracellular waves of cytochrome-c release. To investigate the consequences of these spatial anisotropies in mitochondrial permeabilisation on subsequent effector caspase activation, we devised a mathematical reaction-diffusion model building on a set of partial differential equations.