Distance-based analysis of variance for brain connectivity

The field of neuroimaging dedicated to mapping connections in the brain is increasingly being recognized as key for understanding neurodevelopment and pathology. Networks of these connections are quantitatively represented using complex structures, including matrices, functions, and graphs, which require specialized statistical techniques for estimation and inference about developmental and disorder-related changes. Unfortunately, classical statistical testing procedures are not well suited to high-dimensional testing problems. In the context of global or regional tests for differences in neuroimaging data, traditional analysis of variance (ANOVA) is not directly applicable without first summarizing the data into univariate or low-dimensional features, a process that might mask the salient features of high-dimensional distributions. In this work, we consider a general framework for two-sample testing of complex structures by studying generalized within-group and between-group variances based on distances between complex and potentially high-dimensional observations. We derive an asymptotic approximation to the null distribution of the ANOVA test statistic, and conduct simulation studies with scalar and graph outcomes to study finite sample properties of the test. Finally, we apply our test to our motivating study of structural connectivity in autism spectrum disorder.     

Visual and Olfactory Female-Borne Cues Evoke Male Courtship in the Aphid Parasitoid Aphidius colemani Viereck (Hymenoptera: Braconidae)

We investigated the courtship and mating behavior of the pan-tropical polyphagous endoparasitoid Aphidius colemani Viereck. The courtship and mating displays, the magnitude of male-male sexual approaches and the role of female-borne cues evoking male courtship behavior were quantified. The sequence of events leading to copulation in this parasitoid did not differ from that found for other braconids. Females refused to copulate more than once. Same-sex courtships were observed among males and their possible role in an adaptive context is discussed. Olfactory female-borne cues played a key role in eliciting the courtship responses of males. Males were attracted by freshly dead females, but not by dead females soaked in hexane, nor by visual cues from females alone. Intense male wing fanning behavior was elicited by crushed abdomens of virgin females, suggesting that the female abdomen is the source of a short-distance pheromone crucial in evoking male courtship. Further studies are required to clarify the exact nature of the chemicals involved.     

Strain distribution and linkage relationship of a mouse embryonic hemoglobin variant

Search for structural variants of three globin chains (x, y, z), synthesized only during mouse embryonic hematopoiesis, was carried out by electrophoretic analysis of blood from 12-day embryos, all with C57BL/6 mothers, and fathers from 115 inbred stocks selected for their diverse genetic origins. Structure of the -chains of adult hemoglobins differed among the tested strains, with 57 carrying the Hbb ^sallele, 56 the Hbb ^dallele, and two the Hbb ^pallele. The search revealed no x- or z-chain variants but confirmed and extended knowledge of a previously described y-chain variant. Blood of all embryos sired by males from the 57 Hbb ^sstrains contained only y¹-chains, while blood of all embryos sired by Hbb ^dor Hbb ^pmales contained y2-chains as well as the y¹-chains inherited from their C57 BL/6 mother. The locus controlling structure of the y-chain of mouse embryonic hemoglobins is thus extremely closely linked to the locus controlling structure of adult hemoglobin -chain, with maximum possible recombination frequency less than 0.019.This work was supported in part by Grants CA-01074 from the National Cancer Institute, USPHS, and GM 18684 from the National Institute of General Medical Sciences, in part by Grant ACS-VC58 from The American Cancer Society, in part by grants to the Jackson Laboratory from the Bushrod H. Campbell and Adah F. Hall Charity Fund and the Robert Sterling Clark Foundation, and in part by the Jackson Laboratory Endowment Fund. The Jackson Laboratory is fully accredited by the American Association for Accreditation of Laboratory Animal Care.     

Nest-mate recognition template of guard honeybees (Apis mellifera) is modified by wax comb transfer

In recognition, discriminators use sensory information to make decisions. For example, honeybee (Apis mellifera) entrance guards discriminate between nest-mates and intruders by comparing their odours with a template of the colony odour. Comb wax plays a major role in honeybee recognition. We measured the rejection rates of nest-mate and non-nest-mate worker bees by entrance guards before and after a unidirectional transfer of wax comb from a 'comb donor' hive to a 'comb receiver' hive. Our results showed a significant effect that occurred in one direction. Guards in the comb receiver hive became more accepting of non-nest-mates from the comb donor hive (rejection decreased from 70 to 47%); however, guards in the comb donor hive did not become more accepting of bees from the comb receiver hive. These data strongly support the hypothesis that the transfer of wax comb increases the acceptance of non-nest-mates not by changing the odour of the bees, but by changing the template used by guards.     

Valence and attention in animal behaviour

Zusammenfassung Jeder Gegenstand oder jedes Ereignis, inbezug auf die das Tier ein Gebaren (“behaviour”) zeigt, wird als “valent” bezeichnet, es wird gesagt, dass sie „Valenz” besitzen. Auf Grund der Analyse einer Experimentaluntersuchung vonF. Brock über die „Umwelt” des EinsiedlerkrebsesPagurus arrosor wird gezeigt, dass diese „Valenz” sich auf die Bedürfnisse des Tiers und die Beachtung durch das Tier bezieht. Die Folgerungen des Begriffs der „Valenz” werden entwickelt und die Notwendigkeit wird erwiesen, das Gebaren („behaviour”) der Tiere in seiner Bezogenheit auf ihre eigenen Merkwelten, nicht auf die unsrige, zu betrachten.

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Résumé L'auteur dit de chaque objet ou de chaque événement par rapport auquel l'animal montre du „behaviour”, qu'il est „valent”, qu'il possède de la „valence”. En se basant sur l'analyse des recherches expérimentales deF. Brock sur le „Umwelt” de l'hermitePagurus arrosor, l'auteur démontre que la „valence” est relative aux besoins de l'animal et à l'attention de la part de l'animal. Il développe ensuite les conséquences diverses que l'idée de „valence” implique et il prouve qu'il est nécessaire d'observer le „behaviour” de l'animal par rapport à sa propre perception et non pas par rapport à la n?tre.

     

Spaceflight has compartment- and gene-specific effects on mRNA levels for bone matrix proteins in rat femur

In the presentstudy, we evaluated the possibility that the abnormal bone matrixproduced during spaceflight may be associated with reduced expressionof bone matrix protein genes. To test this possibility, we investigatedthe effects of a 14-day spaceflight (SLS-2 experiment) on steady-statemRNA levels for glyceraldehyde-3-phosphate dehydrogenase (GAPDH),osteocalcin, osteonectin, and prepro-(1) subunit of type I collagenin the major bone compartments of rat femur. There were pronouncedsite-specific differences in the steady-state levels of expression ofthe mRNAs for the three bone matrix proteins and GAPDH in normalweight-bearing rats, and these relationships were altered afterspaceflight. Specifically, spaceflight resulted in decreases in mRNAlevels for GAPDH (decreased in proximal metaphysis), osteocalcin(decreased in proximal metaphysis), osteonectin (decreased in proximaland distal metaphysis), and collagen (decreased in proximal and distalmetaphysis) compared with ground controls. There were no changes inmRNA levels for matrix proteins or GAPDH in the shaft and distalepiphysis. These results demonstrate that spaceflight leads to site-and gene-specific decreases in mRNA levels for bone matrix proteins.These findings are consistent with the hypothesis thatspaceflight-induced decreases in bone formation are caused byconcomitant decreases in expression of genes for bone matrix proteins.