Social Constructionism and Social Representation Theory

This chapter considers how the perspectives of social constructionism and social representations theory can overlap and cross-fertilize more than was once recognized, when the study of change is at stake. This applies particularly to the study of meaning-making through practices and relations via social artifacts. Focusing on those scholars considered to be the main initiators and developers of these two perspectives in social psychology—Serge Moscovici and Kenneth J. Gergen—the authors analyze their works on different levels: meta-theoretical, theoretical, and methodological. Grounding their reasoning on research that they themselves and others have conducted on the two frameworks, mainly on aging in an aging society, the authors call for a further erasure of distinctions between the two. They conclude by suggesting a fruitful future enrichment of the dialogue and a reciprocal cross-fertilization that might overcome nominalistic barriers in the study of social knowledge, particularly where change and continuity are concerned.

Genetic, epigenetic, and environmental mechanisms govern allele-specific gene expression

ABSTRACTAllele-specific expression (ASE) is a phenomenon where one allele is preferentially expressed over the other. Genetic and epigenetic factors cause ASE by altering the final allelic composition of a gene’s product, leading to expression imbalances that can have functional consequences on phenotypes. Environmental signals also impact allele-specific gene regulation, but how they contribute to this crosstalk remains understudied. Here, we explored how allelic genotype, parent-of-origin, tissue type, sex, and dietary fat simultaneously influence ASE biases in a F1 reciprocal cross mouse model. Male and female mice from a F1 reciprocal cross of the LG/J and SM/J strains were fed a high-fat or low-fat diet. We harnessed strain-specific variants to distinguish between two classes of ASE: parent-of-origin dependent (unequal expression based on an allele’s parental origin) and sequence dependent (unequal expression based on an allele’s nucleotide identity). We present a comprehensive genome-wide map of ASE patterns across three metabolically-relevant tissues and nine environmental contexts. We find that both ASE classes are highly dependent on tissue type and environmental context. They vary across metabolic tissues, between males and females, and in response to dietary fat levels. Surprisingly, we also find several genes with inconsistent ASE biases that switched direction across tissues and/or contexts (e.g. SM/J biased in one cohort, LG/J biased in another). Together, our results provide novel insights into how genetic, epigenetic, and environmental mechanisms govern allele-specific gene regulation, which is an essential step towards deciphering the genotype to phenotype map.

The Multiple Facets of Iron Recycling

The production of around 2.5 million red blood cells (RBCs) per second in erythropoiesis is one of the most intense activities in the body. It continuously consumes large amounts of iron, approximately 80% of which is recycled from aged erythrocytes. Therefore, similar to the “making”, the “breaking” of red blood cells is also very rapid and represents one of the key processes in mammalian physiology. Under steady-state conditions, this important task is accomplished by specialized macrophages, mostly liver Kupffer cells (KCs) and splenic red pulp macrophages (RPMs). It relies to a large extent on the engulfment of red blood cells via so-called erythrophagocytosis. Surprisingly, we still understand little about the mechanistic details of the removal and processing of red blood cells by these specialized macrophages. We have only started to uncover the signaling pathways that imprint their identity, control their functions and enable their plasticity. Recent findings also identify other myeloid cell types capable of red blood cell removal and establish reciprocal cross-talk between the intensity of erythrophagocytosis and other cellular activities. Here, we aimed to review the multiple and emerging facets of iron recycling to illustrate how this exciting field of study is currently expanding.

The neurobiology of splitbrain crayfish

Background: They crayfish brain is segmented into two symmetrical hemiganglia. Normally both hemiganglia are in direct communication through a series of well-defined neural bridges that cross de midline to form reciprocal cross connections.Methods: An original study was carried out in the Department of Physiology of the Faculty of Medicine, UNAM during the period from August 2019 to August 2020. 13 Crayfish Procambarus clarkii weighing between 1g to 30g were used. Each eyestalk of the animals was tied to a displacement transducer coupled with a polygraph so that optomotor or electrical activity was bilaterally recorded. The separation of the right from the left hemiganglia from the cerebral or supraesophageal ganglion was performed with a sagittal section, splitbrain (SB).Results: The normal photo motor reflex in crayfish eye is measured as a gradual decrease in the ERG amplitude. During tactile stimulation, the visual activation of both eyestalks in normal crayfish leads to a highly regular bilateral activity. The regular activity can only be altered by disturbing the mechanoreceptors located in the shell surrounding the eyestalks.Conclusions: The procedure presented in this article provides unique characteristics for the study of the nervous system such as a detailed response of the bilateral optomotor reflex.

Establishment of a human three-dimensional chip-based chondro-synovial co-culture joint model for reciprocal cross-talk studies in arthritis research

Rheumatoid arthritis is characterised by a progressive, intermittent inflammation at the synovial membrane, which ultimately leads to the destruction of the synovial joint. The synovial membrane, which is the joint capsule’s inner layer, is lined with fibroblast-like synoviocytes that are the key player supporting persistent arthritis leading to bone erosion and cartilage destruction. While microfluidic models that model molecular aspects of bone erosion between bone-derived cells and synoviocytes have been established, RA’s synovial-chondral axis has yet not been realised using a microfluidic 3D model based on human patient in vitro cultures. Consequently, we established a chip-based three-dimensional tissue co-culture model that simulates the reciprocal cross-talk between individual synovial and chondral organoids. We now demonstrate that chondral organoids, when co-cultivated with synovial organoids, induce a higher degree of cartilage physiology and architecture and show differential cytokine response compared to their respective monocultures highlighting the importance of reciprocal tissue-level cross-talk in the modelling of arthritic diseases.

Establishment of a human three-dimensional chip-based chondro-synovial co-culture joint model for reciprocal cross-talk studies in arthritis research

Rheumatoid arthritis is characterised by a progressive, intermittent inflammation at the synovial membrane, which ultimately leads to the destruction of the synovial joint. The synovial membrane, which is the joint...

Effect of genotype on semen quality traits of main and reciprocal crossbred chickens

Semen quality of cocks is of utmost importance in reproduction. Breeding method, breed, strain and genetic constitution are the major components of the genetic factors capable of affecting the semen quality of cocks. This research seeks to determine the effect of genotype on the semen quality traits of 272 F crossbred cocks produced at day-old by main and 1 reciprocal crossbreeding of 69 Isa Brown and local frizzle feathered, naked neck and normal feathered chickens. The genotypes of the cocks were Isa Brow x frizzle feathered main cross (IBxF), Isa Brown x naked neck main cross (IBxNa), Isa Brown x normal feathered main cross (IBxN), frizzle feathered x Isa Brown reciprocal cross (FxIB), naked neck x Isa Brown reciprocal cross (NaxIB) and normal feathered x Isa Brown reciprocal cross (NxIB). At 36-40 weeks of age, semen was extracted from the cocks by abdominal massage technique and used to evaluate semen volume (SV), sperm motility (SM), sperm concentration (SC) and live sperm (LS) at weekly intervals. Data obtained from the evaluation were subjected to analysisof variance and tested at 5% level of probability. Genotypes differed significantly (P <0.05) in SC at 37-40 weeks and in SM and LS at all ages. There was no significant difference (P>0.05) in SV. Regardless of genotype and age, the mean SV, SM, SC and LS ranged from 0.31±0.02 to 0.24±0.01ml, 71.84±1.33 to 58.75±2.16 %, 3.22±0.02 to2.92±0.02 x109/ml and 71.91±1.37 %, respectively. The NxIB and IBxNa genotypes produced largest numericalsemen volume at 37 and 39 weeks of age respectively. Whereas SC and LS were significantly highest for IBxF and IBxN respectively at week 37, SM was so for IBxN at all ages. Further, the LS of IBxN genotype was significantly highest at 36-38 and 40 weeks of age. The exotic Isa Brown and normal feathered main cross cocks exhibited the best semen quality traits among all genotypes studied and should be selected for improvement of the reproductive characteristics of cocks.