Pigeon homing: Does initial orientation include a ‘preferred compass direction’?

Summary To find out whether the initial orientation of pigeons is affected by a spontaneous directional tendency, as postulated by Wallraff's (1974, 1978, 1982) hypothesis, experienced birds were released at test sites distributed symmetrically around their loft. — The length of the mean vectors of the single releases, the deviations from the home direction, the homeward components as well as the homing speed did not show a correlation with the geographic position of the home direction. Summarizing four sites each on 21 experimental circles, we frequently obtained significant compass vectors, but they varied in direction between 115° ESE and 351° N, depending on what sites had been used, and did not indicate a uniform trend.A preferred compass direction as an integrated part of pigeon navigation, being the reason for the frequently observed deviations from the home direction, could not be confirmed. — The problematic nature of simply pooling the data of several symmetrically distributed test sites and calling any resulting significant vector a preferred compass direction is discussed, together with other possible reasons for asymmetrical distributions of release site biases.Abbreviation PCD preferred compass direction     

Compound genetic ablation of nidogen 1 and 2 causes basement membrane defects and perinatal lethality in mice

Nidogen 1 and 2 are basement membrane glycoproteins, and previous biochemical and functional studies indicate that they may play a crucial role in basement membrane assembly. While they show a divergent expression pattern in certain adult tissues, both have a similar distribution during development. Gene knockout studies in mice demonstrated that the loss of either isoform has no effect on basement membrane formation and organ development, suggesting complementary functions. Here, we show that this is indeed the case. Deficiency of both nidogens in mice resulted in perinatal lethality. Nidogen 1 and 2 do not appear to be crucial in establishing tissue architecture during organ development; instead, they are essential for late stages of lung development and for maintenance and/or integrity of cardiac tissue. These organ defects are not compatible with postnatal survival. Ultrastructural analysis suggests that the phenotypes directly result from basement membrane changes. However, despite the ubiquitous presence of nidogens in basement membranes, defects do not occur in all tissues or in all basement membranes, suggesting a varying spectrum of roles for nidogens in the basement membrane.     

Leptin receptor isoform 219.1: an example of protein evolution by LINE-1-mediated human-specific retrotransposition of a coding SVA element

Phylogenetically new insertions of repetitive sequences may contribute to genome evolution by altering the function of preexisting proteins. One example is the SVA sequence, which forms the C-terminal coding exon of the human leptin receptor isoform 219.1. Here, we report that the SVA insertion into the LEPR locus has occurred after divergence of humans and chimpanzees. The SVA element was inserted into a Hal-1/LINE element present in all monkeys and apes tested. Structural features point toward an integration event that was mediated by the L1 protein machinery acting in trans. Thus, our findings add evidence to the hypothesis that retrotransposition events are a driving force in genomic evolution and that the presence or absence of specific retroelements are one distinguishing feature that separates humans from chimpanzees.     

Identification and characterization of photosystem II chlorophyll a/b binding proteins in Marchantia polymorpha L.

The minor chlorophyll a/b-binding (CAB) proteins of the liverwort Marchantia polymorpha L. were investigated in order to compare the antenna organization and the light-acclimation potential in lower and higher plants. Homologues to the minor CAB proteins CP24, CP26 and CP29 were identified by the following criteria: enrichment in photosystem II preparations, immunological cross-reactivities, spectroscopic properties and protein-fragment amino acid sequences. The high violaxanthin content of the minor CAB proteins in M. polymorpha indicates that their role in protection from high light is comparable in lower and higher plants. Considerably more-alkaline isoelectric points are found for the minor CAB proteins of M. polymorpha than for their higher-plant counterparts. This might be due to a higher content of basic amino acids. While the N-terminal sequence of angiosperm CP29 contains a threonine that becomes phosphorylated during cold stress, this amino acid is substituted by valine in M. polymorpha. Therefore, the regulatory properties of this protein could differ in lower and higher plants. Received: 25 March 1997 / Accepted: 21 July 1997     

Pathways of IAA Production from Tryptophan by Plants and by Their Epiphytic Bacteria: A Comparison

Metabolites of tryptophan were investigated using 2 systems: a bacterial (Peastem homogenates containing the epiphytic bacteria) and a plant system (pea stem sections under sterile conditions). The plant system produces: indolepyruvic acid (IPyA), indoleacetaldehyde (IAAld) indoleacetic acid (IAA), indoleethanol (tryptophol, IAAol), indolecarboxylie acid (ICA), indolecarboxaldehyde (ICAld). Bacteria produce additionally: indoleactic acid (ILA), tryptamine (TNH₂) and the unknown Xb and Yb, but IAAld was not detected. A nonacidic inhibitor extract from pea stems decreases the gain of IAA, IPyA, ILA, Yb. It increases the gain of IAAld, IAAol, TNH₂, Xb, and (only in the bacterial system) ICA and ICAld. Three sites of inhibitor action are suggested, namely the steps Try → IPyA, TNH₂→ IAAld, IAAld → IAA.     

The induction of sun and shade leaves of the European beech (Fagus sylvatica L.): anatomical studies

Summary Primordia from buds of sun and shade twigs of European beech (Fagus sylvatica L.) were collected six times a year for anatomical investigations. Differentiation into sun-leaf and shade-leaf primordia was first observed in early August. Sun-leaf primordia had five, and shade-leaf primordia four layers of mesophyll meristem cells. With potted graft unions of beeches possible structural changes of leaf primordia were investigated. Trees adapted to shade develop sun-leaf primordia when put into full daylight, provided the transfer happened before July. Trees adapted to full daylight developed leaf primordia which remained structurally sun-leaf primordia when the plant was kept under shade conditions. Shadeleaf branches of young beech trees cut in February in order to expose the shade buds to full daylight developed either shade leaves or intermediate shade/sun leaves. These experiments show that the subtending leaf may provide the developing axillary bud with photoassimilates, but its character, whether sun or shade leaf, has no influence on the character of the developing leaf primordia.     

Influence of various factors on quantitative composition of leaf monoterpenes ofPicea abies (L.) Karst

Summary The extractable monoterpenes from needles of two groups of trees — 4-year-old clonal and 20-year-old wild trees — were studied with respect to the influence of individual constitution, needle age, whorl position, and position on branch. Leaf terpene amounts from clonal trees are significantly affected by age and position of the whorl, whereas position on the branch is of minor importance. Developing needles of clonal trees are most strongly affected by age and whorl position and they differ markedly from mature needles in quantitative terpene composition. Wild trees exhibit a very high variation from tree to tree, which obscures the influence of needle age and position. For this reason meaningful tree leaf terpene data will only be derived if large samples of needles of different ages are collected from distinct positions. When comparing different trees, needles should be selected that not only have the same state of development, but also originate from identical positions and have been subjected to the same light treatment.     

Novel Potential Interacting Partners of Fibronectin in Spontaneous Animal Model of Interstitial Cystitis

Feline idiopathic cystitis (FIC) is the only spontaneous animal model for human interstitial cystitis (IC), as both possess a distinctive chronical and relapsing character. Underlying pathomechanisms of both diseases are not clearly established yet. We recently detected increased urine fibronectin levels in FIC cases. The purpose of this study was to gain further insight into the pathogenesis by assessing interacting partners of fibronectin in urine of FIC affected cats. Several candidate proteins were identified via immunoprecipitation and mass spectrometry. Considerable changes in FIC conditions compared to physiological expression of co-purified proteins were detected by Western blot and immunohistochemistry. Compared to controls, complement C4a and thioredoxin were present in higher levels in urine of FIC patients whereas loss of signal intensity was detected in FIC affected tissue. Galectin-7 was exclusively detected in urine of FIC cats, pointing to an important role of this molecule in FIC pathogenesis. Moderate physiological signal intensity of galectin-7 in transitional epithelium shifted to distinct expression in transitional epithelium under pathophysiological conditions. I-FABP expression was reduced in urine and urinary bladder tissue of FIC cats. Additionally, transduction molecules of thioredoxin, NF-κB p65 and p38 MAPK, were examined. In FIC affected tissue, colocalization of thioredoxin and NF-κB p65 could be demonstrated compared to absent coexpression of thioredoxin and p38 MAPK. These considerable changes in expression level and pattern point to an important role for co-purified proteins of fibronectin and thioredoxin-regulated signal transduction pathways in FIC pathogenesis. These results could provide a promising starting point for novel therapeutic approaches in the future.