In Synch but Not in Step: Circadian Clock Circuits Regulating Plasticity in Daily Rhythms

The suprachiasmatic nucleus (SCN) is a network of neural oscillators that program daily rhythms in mammalian behavior and physiology. Over the last decade much has been learned about how SCN clock neurons coordinate together in time and space to form a cohesive population. Despite this insight, much remains unknown about how SCN neurons communicate with one another to produce emergent properties of the network. Here we review the current understanding of communication among SCN clock cells and highlight a collection of formal assays where changes in SCN interactions provide for plasticity in the waveform of circadian rhythms in behavior. Future studies that pair analytical behavioral assays with modern neuroscience techniques have the potential to provide deeper insight into SCN circuit mechanisms

Collective Timekeeping Among Cells of the Master Circadian Clock

The suprachiasmatic nucleus (SCN) of the anterior hypothalamus is the master circadian clock that coordinates daily rhythms in behavior and physiology in mammals. Like other hypothalamic nuclei, the SCN displays an impressive array of distinct cell types characterized by differences in neurotransmitter and neuropeptide expression. Individual SCN neurons and glia are able to display self-sustained circadian rhythms in cellular function that are regulated at the molecular level by a 24h transcriptional–translational feedback loop. Remarkably, SCN cells are able to harmonize with one another to sustain coherent rhythms at the tissue level. Mechanisms of cellular communication in the SCN network are not completely understood, but recent progress has provided insight into the functional roles of several SCN signaling factors. This review discusses SCN organization, how intercellular communication is critical for maintaining network function, and the signaling mechanisms that play a role in this process. Despite recent progress, our understanding of SCN circuitry and coupling is far from complete. Further work is needed to map SCN circuitry fully and define the signaling mechanisms that allow for collective timekeeping in the SCN network

Environmental Circadian Disruption Elevates the IL-6 Response to Lipopolysaccharide in Blood

The immune system is regulated by circadian clocks within the brain and immune cells. Environmental circadian disruption (ECD), consisting of a 6-h phase advance of the light:dark cycle once a week for 4 weeks, elevates the inflammatory response to lipopolysaccharide (LPS) both in vivo and in vitro. This indicates that circadian disruption adversely affects immune function; however, it remains unclear how the circadian system regulates this response under ECD conditions. Here, we develop an assay using ex vivo whole-blood LPS challenge to investigate the circadian regulation of immune responses in mice and to determine the effects of ECD on these rhythms. LPS-induced IL-6 release in whole blood was regulated in a circadian manner, peaking during subjective day under both entrained and free-running conditions. This LPS-induced IL-6 release rhythm was associated with daily variation in both white blood cell counts and immune cell responsiveness. ECD increased the overall level of LPS-induced IL-6 release by increasing immune cell responsiveness and not by affecting immune cell number or the circadian regulation of this rhythm. This indicates that ECD produces pathological immune responses by increasing the proinflammatory responses of immune cells. Also, this newly developed whole blood assay can provide a noninvasive longitudinal method to quantify potential health consequences of circadian disruption in humans

Sexual Differentiation of Circadian Clock Function in the Adrenal Gland

Sex differences in glucocorticoid production are associated with increased responsiveness of the adrenal gland in females. However, the adrenal-intrinsic mechanisms that establish sexual dimorphic function remain ill defined. Glucocorticoid production is gated at the molecular level by the circadian clock, which may contribute to sexual dimorphic adrenal function. Here we examine sex differences in the adrenal gland using an optical reporter of circadian clock function. Adrenal glands were cultured from male and female Period2::Luciferase (PER2::LUC) mice to assess clock function in vitro in real time. We confirm that there is a pronounced sex difference in the intrinsic capacity to sustain PER2::LUC rhythms in vitro, with higher amplitude rhythms in adrenal glands collected from males than from females. Changes in adrenal PER2::LUC rhythms over the reproductive life span implicate T as an important factor in driving sex differences in adrenal clock function. By directly manipulating hormone levels in adult mice in vivo, we demonstrate that T increases the amplitude of PER2::LUC rhythms in adrenal glands of both male and female mice. In contrast, we find little evidence that ovarian hormones modify adrenal clock function. Lastly, we find that T in vitro can increase the amplitude of PER2::LUC rhythms in male adrenals but not female adrenals, which suggests the existence of sex differences in the mechanisms of T action in vivo. Collectively these results reveal that activational effects of T alter circadian timekeeping in the adrenal gland, which may have implications for sex differences in stress reactivity and stress-related disorders

Examining Strategies School Managers Employ to Motivate Teachers: A Case of Secondary School Teachers in Kyenjojo District, Western

In order to realize the educational objectives it requires motivated and satisfied teachers however, majority of teachers in Uganda are not motivated. This is shown by the instability in the teaching profession, such as poor performance of teachers, high turnovers, and absenteeism and in the end the learner is highly affected because most fail to get the required education. People need to develop their potentials and this can only be done if their esteems are high.  Teachers need to be appreciated at their work places in order to induce creativity and motivation in them. Despite these observations, it is not clear which strategy would account best for teachers’ motivation and job satisfaction in Uganda. This study examines the strategies school managers use to motivate teachers. Descriptive Survey design was used to gather factual information from the targeted population without creating contradiction. The purpose of descriptive surveys, according to Ezeani (1998), is to collect detailed and factual information that describes an existing phenomenon. On the other hand, Kothari (2003) says   this method is easy for securing information concerning an existing phenomenon from all or a chosen number of the population of the concerned universe. Strategies school managers employ to motivate teachers were measured by survey in a sample of 50 teachers The target population, from which the sample was drawn for the study, consisted of thirty (30) teachers  in public and fifty (50) teachers  in private secondary school, plus  (8)  principals in both public and private Secondary Schools of Kyenjojo District. The study used both probability sampling and non probability sampling designs. In general eight (8) secondary schools in Kyenjojo District provided eighty eight respondents (89). This sample represented the general teacher population in both public and private schools Kyenjojo who are employed byUganda Teacher Service Commission (U.T.S.C). The general number of teachers in Kyenjojo could not be established, because some teachers are registered by U.T.S.C and others are privately employed. The findings of the study were: head teachers allow their teachers to go for in service training as a strategy for motivating teachers among others strategies as elaborated in the findings. Key Words: Strategies, Managers, Motivation and Teacher

Examining Challenges Encountered in Promoting Teacher Job Satisfaction in Secondary Schools of Kyenjojo District Western Uganda

Job satisfaction can be understood as a collection of attitudes, feelings that workers have about their job. The objective of this study was identifying challenges faced in promoting teacher job satisfaction in secondary schools of Kyenjojo District Western Uganda.  The Study was descriptive in nature and copies of a questionnaire were used to collect data. The data were collected  from which the sample was drawn for the study, consisted of thirty (30) teachers in public and fifty (50) teachers in private secondary school, plus (8) principals in both public and private Secondary Schools of Kyenjojo District. The findings were Job satisfaction is a hard factor to determine by managers in education the findings were drawn after the descriptive and inferential analysis, Means, Standard Deviation and, were run to test the hypotheses. Generally teachers were less satisfied with advancement, compensation, supervision, human-relation, and working conditions. Keywords: Job satisfaction, Attitude, Public schools, working conditions

TB178: Methods for Evaluating Carbon Fractions in Forest Soils: A Review

This publication was developed as part of an effort to evaluate the existing methodologies for determining carbon fractions in soils that might be applied to the question of forest soil C sequestration. A great deal of research has been done on this topic although often focused on agronomic soils. Forest land managers will be increasingly interested in identifying methods to monitor and to evaluate the effects of forest practices on soil C reserves. As well researchers are interested in this and the logical linkages to N cycling. Ultimately practical methods that can be widely utilized will be needed; these may come from current methods or be developed through research. This review offers a framework for this area of investigation.https://digitalcommons.library.umaine.edu/aes_techbulletin/1030/thumbnail.jp