Adolescent Changes in Dopamine D1 Receptor Expression in Orbitofrontal Cortex and Piriform Cortex Accompany an Associative Learning Deficit

The orbitofrontal cortex (OFC) and piriform cortex are involved in encoding the predictive value of olfactory stimuli in rats, and neural responses to olfactory stimuli in these areas change as associations are learned. This experience-dependent plasticity mirrors task-related changes previously observed in mesocortical dopamine neurons, which have been implicated in learning the predictive value of cues. Although forms of associative learning can be found at all ages, cortical dopamine projections do not mature until after postnatal day 35 in the rat. We hypothesized that these changes in dopamine circuitry during the juvenile and adolescent periods would result in age-dependent differences in learning the predictive value of environmental cues. Using an odor-guided associative learning task, we found that adolescent rats learn the association between an odor and a palatable reward significantly more slowly than either juvenile or adult rats. Further, adolescent rats displayed greater distractibility during the task than either juvenile or adult rats. Using real-time quantitative PCR and immunohistochemical methods, we observed that the behavioral deficit in adolescence coincides with a significant increase in D1 dopamine receptor expression compared to juvenile rats in both the OFC and piriform cortex. Further, we found that both the slower learning and increased distractibility exhibited in adolescence could be alleviated by experience with the association task as a juvenile, or by an acute administration of a low dose of either the dopamine D1 receptor agonist SKF-38393 or the D2 receptor antagonist eticlopride. These results suggest that dopaminergic modulation of cortical function may be important for learning the predictive value of environmental stimuli, and that developmental changes in cortical dopaminergic circuitry may underlie age-related differences in associative learning.     

On the shoulders of giants: a historical perspective of unique experimental methods in mammary gland research

While most organs undergo development in utero, the mouse mammary gland orchestrates five major developmental stages following birth: pre-puberty, puberty, pregnancy, lactation, and involution. Induced by both local and systemic factors, these five developmental stages transpire with dramatic alterations in glandular morphology and cellular function. As an experimental system, the mammary gland provides remarkable accessibility to processes regulating stem cell function, hormone response, and epithelial-stromal-extracellular matrix interactions. This review will provide a historical perspective of the unique in vitro and in vivo techniques used to study the mammary gland and how these methods have provided valuable insight into the biology of this organ.     

Transplantation of Autologous Adipose Stem Cells Lacks Therapeutic Efficacy in the Experimental Autoimmune Encephalomyelitis Model

Multiple sclerosis (MS), characterized by chronic inflammation, demyelination, and axonal damage, is a complicated neurological disease of the human central nervous system. Recent interest in adipose stromal/stem cell (ASCs) for the treatment of CNS diseases has promoted further investigation in order to identify the most suitable ASCs. To investigate whether MS affects the biologic properties of ASCs and whether autologous ASCs from MS-affected sources could serve as an effective source for stem cell therapy, cells were isolated from subcutaneous inguinal fat pads of mice with established experimental autoimmune encephalomyelitis (EAE), a murine model of MS. ASCs from EAE mice and their syngeneic wild-type mice were cultured, expanded, and characterized for their cell morphology, surface antigen expression, osteogenic and adipogenic differentiation, colony forming units, and inflammatory cytokine and chemokine levels in vitro. Furthermore, the therapeutic efficacy of the cells was assessed in vivo by transplantation into EAE mice. The results indicated that the ASCs from EAE mice displayed a normal phenotype, typical MSC surface antigen expression, and in vitro osteogenic and adipogenic differentiation capacity, while their osteogenic differentiation capacity was reduced in comparison with their unafflicted control mice. The ASCs from EAE mice also demonstrated increased expression of pro-inflammatory cytokines and chemokines, specifically an elevation in the expression of monocyte chemoattractant protein-1 and keratin chemoattractant. In vivo, infusion of wild type ASCs significantly ameliorate the disease course, autoimmune mediated demyelination and cell infiltration through the regulation of the inflammatory responses, however, mice treated with autologous ASCs showed no therapeutic improvement on the disease progression.     

Disentangling phylogenetic constraints from selective forces in the evolution of trematode transmission stages

The transmission stages of parasites are key determinants of parasite fitness, but they also incur huge mortality. Yet the selective forces shaping the sizes of transmission stages remain poorly understood. We ran a comparative analysis of interspecific variation in the size of transmission stages among 404 species of parasitic trematodes. There are two transmission steps requiring infective stages in the life cycle of trematodes: transmission from the definitive to the first intermediate (snail) host is achieved by eggs and/or the miracidia hatched from those eggs, and transmission from the first to the second intermediate host is achieved by free-swimming cercariae. The sizes of these stages are under strong phylogenetic constraints. Our results show that taxonomy explains >50% of the unaccounted variance in linear mixed models, with most of the variance occurring at the superfamily level. The models also demonstrated that mollusc size is positively associated with egg volume, miracidial volume and cercarial body volume, but not with the relative size of the cercarial tail. In species where they encyst on substrates, cercariae have significantly larger bodies than in species penetrating chordates, although the relative size of the cercarial tail of species using chordates as second intermediate hosts was larger than in other trematode species. Habitat also matters, with larger cercarial tails seen in freshwater trematodes than in marine ones, and larger miracidial volumes in freshwater species than in marine ones. Finally, the latitude (proxy for local temperature) at which the trematode species were collected had no effect on the sizes of transmission stages. We propose that resource availability within the snail host, the probability of contacting a host, and the density and viscosity of the water medium combine to select for different transmission stage sizes.     

Inhibitory effects of ethacrynic acid analogues lacking the α,β-unsaturated carbonyl unit and para-acylated phenols on human cancer cells

A series of ethacrynic acid analogues, lacking the α,β-unsaturated carbonyl unit, was synthesized and subsequently evaluated for their ability to inhibit the migration of human breast cancer cells, Hs578Ts(i)8 as well as of human prostate cancer cells, C4-2B. These cell lines provide a good model system to study migration and invasion, since they represent metastatic cancer. Our studies show that ethacrynic acid analogues with methyl substituents at the aromatic ring demonstrate no inhibitory effect on the migration of both cancer cell lines, whereas a precursor in the synthesis of these ethacrynic acid analogues (II-1, a para-acylated m-cresol) is an excellent inhibitor of the migration of both cancer cell lines.     

Influence of soil temperature and moisture on the dissolved carbon,nitrogen, and phosphorus in organic matter entering lake ecosystems

Concentrations of terrestrially derived dissolved organic matter (DOM) have been increasing in many north temperate and boreal lakes for over two decades. The concentration of DOM in lakes is influenced by a number of environmental factors, but there is still considerable debate about how the availability of terrestrial DOM, and associated dissolved nitrogen and phosphorus, may be affected by drivers of climatic change. Using experimental and observational methods, we considered how changes in soil temperature and moisture affected the composition of carbon, nitrogen, and phosphorus entering freshwater lakes. In our experiment, organic soil cores were collected from the wetland shoreline of a darkly-stained seepage lake in northern Wisconsin, USA and manipulated in laboratory with temperature and moisture treatments. During the 28-day study, soil leachate was sampled and analyzed for optical properties of DOM via UV/Vis absorbance, as well as concentrations of dissolved organic carbon (DOC), total dissolved nitrogen, and total dissolved phosphorus (TDP). DOM optical properties were particularly sensitive to moisture, with drier scenarios resulting in DOM of lower molecular weight and aromaticity. Warmer temperatures led to lower DOC and TDP concentrations. To consider long-term relationships between climate and lake chemical properties, we analyzed long-term water chemistry data from two additional Wisconsin lakes from the long term ecological research (LTER) project in a cross correlation analysis with Palmer drought severity index data. Analysis of the LTER data supported our experimental results that soil moisture has a significant effect on the quality of DOM entering lakes and that climate may significantly affect lake chemical properties. Although unexpected in terms of DOM loading for climate change scenarios, these results are consistent with patterns of decomposition in organic soils and may be attributed to an increase in soil DOM processing.     

Induction of neutrophil extracellular traps by Campylobacter jejuni

Campylobacter jejuni is the leading cause of bacterial‐derived gastroenteritis worldwide and can lead to several post‐infectious inflammatory disorders. Despite the prevalence and health impacts of the bacterium, interactions between the host innate immune system and C. jejuni remain poorly understood. To expand on earlier work demonstrating that neutrophils traffic to the site of infection in an animal model of campylobacteriosis, we identified significant increases in several predominantly neutrophil‐derived proteins in the faeces of C. jejuni‐infected patients, including lipocalin‐2, myeloperoxidase and neutrophil elastase. In addition to demonstrating that these proteins significantly inhibited C. jejuni growth, we determined they are released during formation of C. jejuni‐induced neutrophil extracellular traps (NETs). Using quantitative and qualitative methods, we found that purified human neutrophils are activated by C. jejuni and exhibit signatures of NET generation, including presence of protein arginine deiminase‐4, histone citrullination, myeloperoxidase, neutrophil elastase release and DNA extrusion. Production of NETs correlated with C. jejuni phagocytosis/endocytosis and invasion of neutrophils suggesting that host‐ and bacterial‐mediated activities are responsible for NET induction. Further, NET‐like structures were observed within intestinal tissue of C. jejuni‐infected ferrets. Finally, induction of NETs significantly increased human colonocyte cytotoxicity, indicating that NET formation during C. jejuni infection may contribute to observed tissue pathology. These findings provide further understanding of C. jejuni–neutrophil interactions and inflammatory responses during campylobacteriosis.     

A Novel Cryptochrome-Dependent Oscillator in Neurospora crassa

Several lines of evidence suggest that the circadian clock is constructed of multiple molecular feedback oscillators that function to generate robust rhythms in organisms. However, while core oscillator mechanisms driving specific behaviors are well described in several model systems, the nature of other potential circadian oscillators is not understood. Using genetic approaches in the fungus Neurospora crassa, we uncovered an oscillator mechanism that drives rhythmic spore development in the absence of the well-characterized FRQ/WCC oscillator (FWO) and in constant light, conditions under which the FWO is not functional. While this novel oscillator does not require the FWO for activity, it does require the blue-light photoreceptor CRYPTOCHROME (CRY); thus, we call it the CRY-dependent oscillator (CDO). The CDO was uncovered in a strain carrying a mutation in cog-1 (cry-dependent oscillator gate-1), has a period of ∼1 day in constant light, and is temperature-compensated. In addition, cog-1 cells lacking the circadian blue-light photoreceptor WC-1 respond to blue light, suggesting that alternate light inputs function in cog-1 mutant cells. We show that the blue-light photoreceptors VIVID and CRY compensate for each other and for WC-1 in CRY-dependent oscillator light responses, but that WC-1 is necessary for circadian light entrainment.     

Weather underground: Subsurface hydrologic processes mediate tree vulnerability to extreme climatic drought

Drought extent and severity have increased and are predicted to continue to increase in many parts of the world. Understanding tree vulnerability to drought at both individual and species levels is key to ongoing forest management and preparation for future transitions in community composition. The influence of subsurface hydrologic processes is particularly important in water‐limited ecosystems, and is an under‐studied aspect of tree drought vulnerability. With California's 2013–2016 extraordinary drought as a natural experiment, we studied four co‐occurring woodland tree species, blue oak (Quercus douglasii), valley oak (Quercus lobata), gray pine (Pinus sabiniana), and California juniper (Juniperus californica), examining drought vulnerability as a function of climate, lithology and hydrology using regional aerial dieback surveys and site‐scale field surveys. We found that in addition to climatic drought severity (i.e., rainfall), subsurface processes explained variation in drought vulnerability within and across species at both scales. Regionally for blue oak, severity of dieback was related to the bedrock lithology, with higher mortality on igneous and metamorphic substrates, and to regional reductions in groundwater. At the site scale, access to deep subsurface water, evidenced by stem water stable isotope composition, was related to canopy condition across all species. Along hillslope gradients, channel locations supported similar environments in terms of water stress across a wide climatic gradient, indicating that subsurface hydrology mediates species’ experience of drought, and that areas associated with persistent access to subsurface hydrologic resources may provide important refugia at species’ xeric range edges. Despite this persistent overall influence of the subsurface environment, individual species showed markedly different response patterns. We argue that hydrologic niche segregation can be a useful lens through which to interpret these differences in vulnerability to climatic drought and climate change.