University of Konstanz

About: University of Konstanz is a education organization based out in Konstanz, Baden-Württemberg, Germany. It is known for research contribution in the topics: Population & Visualization. The organization has 12115 authors who have published 27401 publications receiving 951162 citations. The organization is also known as: University of Constance & Universität Konstanz.

Structure of cytochrome c nitrite reductase

Abstract: The enzyme cytochrome c nitrite reductase catalyses the six-electron reduction of nitrite to ammonia as one of the key stepsin the biological nitrogen cycle1, where it participates inthe anaerobic energy metabolism of dissimilatory nitrate ammonification2. Here we report on the crystal structure of this enzyme from the microorganism Sulfurospirillum deleyianum, which we solved by multiwavelength anomalous dispersion methods. We propose a reaction scheme for the transformation of nitrite based on structural and spectroscopic information. Cytochrome c nitrite reductase is a functional dimer, with 10 close-packed haem groups of type c and an unusual lysine-coordinated high-spin haem at the active site. By comparing the haem arrangement of this nitrite reductase with that of other multihaem cytochromes, we have been able to identify a family of proteins in which the orientation of haem groups is conserved whereas structure and function are not.

A guide to null models for animal social network analysis.

Abstract: Null models are an important component of the social network analysis toolbox. However, their use in hypothesis testing is still not widespread. Furthermore, several different approaches for constructing null models exist, each with their relative strengths and weaknesses, and often testing different hypotheses.In this study, I highlight why null models are important for robust hypothesis testing in studies of animal social networks. Using simulated data containing a known observation bias, I test how different statistical tests and null models perform if such a bias was unknown.I show that permutations of the raw observational (or 'pre-network') data consistently account for underlying structure in the generated social network, and thus can reduce both type I and type II error rates. However, permutations of pre-network data remain relatively uncommon in animal social network analysis because they are challenging to implement for certain data types, particularly those from focal follows and GPS tracking.I explain simple routines that can easily be implemented across different types of data, and supply R code that applies each type of null model to the same simulated dataset. The R code can easily be modified to test hypotheses with empirical data. Widespread use of pre-network data permutation methods will benefit researchers by facilitating robust hypothesis testing.

Parallel Olfactory Systems in Insects: Anatomy and Function

Abstract: A striking commonality across insects and vertebrates is the recurring presence of parallel olfactory subsystems, suggesting that such an organization has a highly adaptive value. Conceptually, two different categories of parallel systems must be distinguished. In one, specific sensory organs or processing streams analyze different chemical stimuli (segregate parallel systems). In the other, similar odor stimuli are processed but analyzed with respect to different features (dual parallel systems). Insects offer many examples for both categories. For example, segregate parallel systems for different chemical stimuli are realized in specialized neuronal streams for processing sex pheromones and CO2. Dual parallel streams related to similar or overlapping odor stimuli are prominent in Hymenoptera. Here, a clear separation of sensory tracts to higher-order brain centers is present despite no apparent differences regarding the classes or categories of olfactory stimuli being processed. In this paper, we review...

Why Does Writing About Important Values Reduce Defensiveness? Self-Affirmation and the Role of Positive Other-Directed Feelings

Abstract: Previous research has repeatedly shown that writing about an important value, compared with writing about an unimportant value, reduces defensiveness in response to self-threatening information, but has not identified why. Study 1 showed that participants who wrote about an important value reported more positive other-directed feelings, such as love and connection, than participants who wrote about an unimportant value. Study 2 replicated this effect, and showed that loving and connected feelings, but not positive or negative self-directed feelings, completely accounted for the effect of a values-affirmation manipulation on smokers' acceptance of information indicating that smoking harms health. These studies, in concert with previous research, suggest that values affirmation reduces defensiveness via self-transcendence, rather than self-integrity (i.e., self-worth or self-images).

Timing of Genome Duplications Relative to the Origin of the Vertebrates: Did Cyclostomes Diverge before or after?

Abstract: Two rounds of whole-genome duplications are thought to have played an important role in the establishment of gene repertoires in vertebrates. These events occurred during chordate evolution after the split of the urochordate and cephalochordate lineages but before the radiation of extant gnathostomes (jawed vertebrates). During this interval, diverse agnathans (jawless fishes), including cyclostomes (hagfishes and lampreys), diverged. However, there is no solid evidence for the timing of these genome duplications in relation to the divergence of cyclostomes from the gnathostome lineage. We conducted cDNA sequencing in diverse early vertebrates for members of homeobox-containing (Dlx and ParaHox) and other gene families that would serve as landmarks for genome duplications. Including these new sequences, we performed a molecular phylogenetic census using the maximum likelihood method for 55 gene families. In most of these gene families, we detected many more gene duplications before the cyclostome-gnathostome split, than after. Many of these gene families (e.g., visual opsins, RAR, Notch) have multiple paralogs in conserved, syntenic genomic regions that must have been generated by large-scale duplication events. Taken together, this indicates that the genome duplications occurred before the cyclostome-gnathostome split. We propose that the redundancy in gene repertoires possessed by all vertebrates, including hagfishes and lampreys, was introduced primarily by genome duplications. Apart from subsequent lineage-specific modifications, these ancient genome duplication events might serve generally to distinguish vertebrates from invertebrates at the genomic level.