Climate change is poised to alter mountain stream ecosystem processes via organismal phenological shifts.

Climate change is affecting the phenology of organisms and ecosystem processes across a wide range of environments. However, the links between organismal and ecosystem process change in complex communities remain uncertain. In snow-dominated watersheds, snowmelt in the spring and early summer, followed by a long low-flow period, characterizes the natural flow regime of streams and rivers. Here, we examined how earlier snowmelt will alter the phenology of mountain stream organisms and ecosystem processes via an outdoor mesocosm experiment in stream channels in the Eastern Sierra Nevada, California. The low-flow treatment, simulating a 3- to 6-wk earlier return to summer baseflow conditions projected under climate change scenarios in the region, increased water temperature and reduced biofilm production to respiration ratios by 32%. Additionally, most of the invertebrate species explaining community change (56% and 67% of the benthic and emergent taxa, respectively), changed in phenology as a consequence of the low-flow treatment. Further, emergent flux pulses of the dominant insect group (Chironomidae) almost doubled in magnitude, benefitting a generalist riparian predator. Changes in both invertebrate community structure (composition) and functioning (production) were mostly fine-scale, and response diversity at the community level stabilized seasonally aggregated responses. Our study illustrates how climate change in vulnerable mountain streams at the rain-to-snow transition is poised to alter the dynamics of stream food webs via fine-scale changes in phenology-leading to novel predator-prey "matches" or "mismatches" even when community structure and ecosystem processes appear stable at the annual scale.

Relationships between biodiversity and ecosystem functioning proxies strengthen when approaching chemosynthetic deep-sea methane seeps.

As biodiversity loss accelerates globally, understanding environmental influence over biodiversity-ecosystem functioning (BEF) relationships becomes crucial for ecosystem management. Theory suggests that resource supply affects the shape of BEF relationships, but this awaits detailed investigation in marine ecosystems. Here, we use deep-sea chemosynthetic methane seeps and surrounding sediments as natural laboratories in which to contrast relationships between BEF proxies along with a gradient of trophic resource availability (higher resource methane seep, to lower resource photosynthetically fuelled deep-sea habitats). We determined sediment fauna taxonomic and functional trait biodiversity, and quantified bioturbation potential (BPc), calcification degree, standing stock and density as ecosystem functioning proxies. Relationships were strongly unimodal in chemosynthetic seep habitats, but were undetectable in transitional 'chemotone' habitats and photosynthetically dependent deep-sea habitats. In seep habitats, ecosystem functioning proxies peaked below maximum biodiversity, perhaps suggesting that a small number of specialized species are important in shaping this relationship. This suggests that absolute biodiversity is not a good metric of ecosystem 'value' at methane seeps, and that these deep-sea environments may require special management to maintain ecosystem functioning under human disturbance. We promote further investigation of BEF relationships in non-traditional resource environments and emphasize that deep-sea conservation should consider 'functioning hotspots' alongside biodiversity hotspots.

Observations from the emergency management of dialysis patients evacuated from the US Virgin Islands to Puerto Rico following hurricane Irma.

Two category 5 hurricanes, Irma and Maria, arrived in the Caribbean in September 2017 in rapid succession. On September 6, Irma devastated the islands of St. Thomas and St. John, in the Virgin Islands of the United States (USVI). Most medical infrastructure was damaged, including hemodialysis facilities, paralyzing dialysis operations. After Irma's landfall, Puerto Rico served as a safehaven for thousands of displaced and repatriated persons from the impacted islands. These included a cohort of 129 hemodialysis patients evacuated from St. Thomas, USVI to San Juan, Puerto Rico from September 9-11, 2017. The hemodialysis patients arrived first at hotels in San Juan and were then transferred to a Special Needs Shelter, run by the Commonwealth of Puerto Rico and located in the Puerto Rico Convention Center. With the imminent arrival of Hurricane Maria, most patients were evacuated on September 19 to a special needs shelter on the campus of the Florida International University, in Miami, Florida. While in San Juan, hemodialysis treatments were provided by local nephrologists working with local hemodialysis centers. Here, we describe the challenges and the emergency management actions taken to ensure continuity of care, including providing dialysis, general medical care, shelter, food and transportation for USVI dialysis patients during their stay in San Juan, Puerto Rico. We describe here the experiences of federal and host state/territorial officials in the special needs shelter, in the context of the state/territorial and federal response to disasters, in order to provide ideas about challenges, solutions, and approaches to coordinating care for dialysis patients evacuated from a disaster.

Integrating ecosystem-service tradeoffs into land-use decisions.

Recent high-profile efforts have called for integrating ecosystem-service values into important societal decisions, but there are few demonstrations of this approach in practice. We quantified ecosystem-service values to help the largest private landowner in Hawaii, Kamehameha Schools, design a land-use development plan that balances multiple private and public values on its North Shore land holdings (Island of O'ahu) of ∼10,600 ha. We used the InVEST software tool to evaluate the environmental and financial implications of seven planning scenarios encompassing contrasting land-use combinations including biofuel feedstocks, food crops, forestry, livestock, and residential development. All scenarios had positive financial return relative to the status quo of negative return. However, tradeoffs existed between carbon storage and water quality as well as between environmental improvement and financial return. Based on this analysis and community input, Kamehameha Schools is implementing a plan to support diversified agriculture and forestry. This plan generates a positive financial return ($10.9 million) and improved carbon storage (0.5% increase relative to status quo) with negative relative effects on water quality (15.4% increase in potential nitrogen export relative to status quo). The effects on water quality could be mitigated partially (reduced to a 4.9% increase in potential nitrogen export) by establishing vegetation buffers on agricultural fields. This plan contributes to policy goals for climate change mitigation, food security, and diversifying rural economic opportunities. More broadly, our approach illustrates how information can help guide local land-use decisions that involve tradeoffs between private and public interests.

Analysis of the expression of cytoskeletal proteins of Taenia crassiceps ORF strain cysticerci (Cestoda).

The Taenia crassiceps ORF strain is used to generate a murine model of cysticercosis, which is used for diagnosis, evaluation of drugs, and vaccination. This particular strain only exists as cysticerci, is easily maintained under in vivo and in vitro conditions, and offers an excellent model for studying the cytoskeletons of cestodes. In this study, several experimental approaches were used to determine the tissue expression of its cytoskeletal proteins. The techniques used were microscopy (video, confocal, and transmission electron), one-dimensional (1D) and two-dimensional (2D) electrophoresis, immunochemistry, and mass spectrometry. The tissue expression of actin, tubulin, and paramyosin was assessed using microscopy, and their protein isoforms were determined with 1D and 2D electrophoresis and immunochemistry. Nineteen spots were excised from a proteomic gel and identified by liquid chromatography-tandem mass spectrometry and immunochemistry. The proteins identified were classic cytoskeletal proteins, metabolic enzymes, and proteins with diverse biological functions, but mainly involved in detoxification activities. Research suggests that most noncytoskeletal proteins interact with actin or tubulin, and the results of the present study suggest that the proteins identified may be involved in supporting the dynamics and plasticity of the cytoskeleton of T. crassiceps cysticerci. These results contribute to our knowledge of the cellular biology and physiology of cestodes.

Female proportion has a stronger influence on dispersal than body size in nematodes of mountain lakes.

Nematodes disperse passively and are amongst the smallest invertebrates on Earth. Free-living nematodes in mountain lakes are highly tolerant of environmental variations and are thus excellent model organisms in dispersal studies, since species-environment relationships are unlikely to interfere. In this study, we investigated how population or organism traits influence the stochastic physical nature of passive dispersal in a topologically complex environment. Specifically, we analyzed the influence of female proportion and body size on the geographical distribution of nematode species in the mountain lakes of the Pyrenees. We hypothesized that dispersal is facilitated by (i) a smaller body size, which would increase the rate of wind transport, and (ii) a higher female proportion within a population, which could increase colonization success because many nematode species are capable of parthenogenetic reproduction. The results showed that nematode species with a low proportion of females tend to have clustered spatial distributions that are not associated with patchy environmental conditions, suggesting greater barriers to dispersal. When all species were pooled, the overall proportion of females tended to increase at the highest elevations, where dispersal between lakes is arguably more difficult. The influence of body size was barely relevant for nematode distributions. Our study highlights the relevance of female proportion as a mechanism that enhances the dispersal success of parthenogenetic species, and that female sex is a determining factor in metacommunity connectivity.

Waste barrel contamination and macrobenthic communities in the San Pedro Basin DDT dumpsite.

Industrial waste barrels were discarded from 1947 to 1961 at a DDT dumpsite in the San Pedro Basin (SPB) in southern California, USA at ~890 m. The barrels were studied for effects on sediment concentrations of DDX, PCBs, PAHs and sediment properties, and on benthic macrofaunal assemblages, including metazoan meiofaunal taxa >0.3 mm. DDX concentration was highest in the 2-6 cm fraction of the 10-cm deep cores studied but exhibited no correlation with macrofaunal density, composition or diversity. Macrofaunal diversity was lowest and distinct in sediments within discolored halos surrounding the barrels. Low macrobenthos density and diversity, high dominance by Entoprocta, and numerical prevalence of large nematodes may result from the very low oxygen concentrations in bottom waters (< 4.4 µM). There is potential for macrofauna to remobilize DDX into the water column and ultimately the food web in the SPB.

Antiproliferative and Antibacterial Activity of Polyporoid Fungi from Veracruz, Mexico.

Polyporoid fungi represent a vast source of bioactive compounds with potential pharmacological applications. The importance of polyporoid fungi in traditional Chinese medicine has led to an extensive use of some species of Ganoderma for promoting health and longevity because their consumption is associated with several bioactivities. Nevertheless, bioactivity of some other members of the Polyporaceae family has also been reported. This work reports the antiproliferative and antibacterial activity of crude extracts obtained from fruiting bodies of polypore fungi collected from the central region of Veracruz, Mexico, aimed at understanding the diversity of polypore species with potential pharmacological applications. 29 collections were identified macro- and microscopically in 19 species of polyporoid fungi, belonging to 13 genera. The antiproliferative activity screening of extracts against solid tumor cell lines (A549, SW1573, HeLa, HBL-100, T-47D, WiDr) allow us to identify four extracts with strong bioactivity [half-maximal growth inhibition (GI50) ≤ 50 µg/mL]. After this, a phylogenetic analysis of DNA sequences from the ITS region obtained from bioactive specimens allowed us to identify three extracts as Pycnoporus sanguineus (GI50 = ≤ 10 µg/mL) and the fourth bioactive extract as Ganoderma oerstedii (GI50 = < 50 µg/mL. Likewise, extracts from P. sanguineus showed mild or moderate antibacterial activity against Escherichia coli, Staphylococcus aureus and Xanthomonas albilineas. Bioprospecting studies of polyporoid fungi add to the knowledge of the diversity of macrofungi in Mexico and allow us to select one of the bioactive P. sanguineus to continue the pursuit of bioactive compounds through mycochemical studies.

Psychological stress responses to a live performance by professional flamenco dancers.

Dance is a high demanding discipline that involves physiological and psychological pressures. The pressure increases when dancers perform in front of an audience that, on a physiological level, can generate hormonal responses similar to those of an athlete before a competition for social status. Low levels of testosterone (T) and high levels of cortisol (C) are related to a decrease in performance and an increase in the risk of injury. Therefore, this study sets out to analyse hormone response patterns in professional flamenco dance performances depending on whether the performances are completed successfully and whether there are differences by sex and professional category. Saliva specimens (2-5 ml) were taken from the participants before and after the performance. Samples were immunoassayed by duplicate to analyze momentary fluctuations in two hormones regularly used in studies with professional athletes. The results showed significant differences in solo dancers' T responses before and after the performance (p < 0.01), suggesting that the dancing role in the show (soloist or corps the ballet) and responsibility over the performance were important modulators to the hormone responses observed.

Isolation controls reestablishment mechanisms and post-drying community structure in an intermittent stream.

Biota in disturbance-prone landscapes have evolved a variety of strategies to persist long term, either locally (resistance) or by regional recolonization (resilience). Habitat fragmentation and isolation can limit the availability of recolonization pathways, and thus the dynamics of post-disturbance community reestablishment. However, empirical studies on how isolation may control the mechanisms that enable community recovery remain scarce. Here, we studied a pristine intermittent stream (Chalone Creek, Pinnacles National Park, California) to understand how isolation (distance from a perennial pool) alters invertebrate community recolonization after drying. We monitored benthic invertebrate reestablishment during the rewetting phase along a ~2-km gradient of isolation, using mesh traps that selected for specific recolonization pathways (i.e., drift, flying, swimming/crawling, and vertical migration from the hyporheic). We collected daily emigration samples, surveyed the reestablished benthic community after 6 weeks, and compared assemblages across trap types and sites. We found that isolation mediated migration dynamics by delaying peak vertical migration from the hyporheic by ca. 1 day on average per 250 m of dry streambed. The relative importance of reestablishment mechanisms varied longitudinally-with more resistance strategists (up to 99.3% of encountered individuals) in the upstream reaches, and increased drift and aerial dispersers in the more fragmented habitats (up to 17.2% and 18%, respectively). Resistance strategists persisting in the hyporheic dominated overall (88.2% of individuals, ranging 52.9%-99.3% across sites), but notably most of these organisms subsequently outmigrated downstream (85.6% on average, ranging 52.1%-96% across sites). Thus, contrary to conventional wisdom, resistance strategists largely contributed to downstream resilience as well as to local community recovery. Finally, increased isolation was associated with a general decrease in benthic invertebrate diversity, and up to a 3-fold increase in the relative abundance of drought-resistant stoneflies. Our results advance the notion that understanding spatial context is key to predicting post-disturbance community dynamics. Considering the interaction between disturbance and fragmentation may help inform conservation in ecosystems that are subject to novel environmental regimes.

Large Pneumoperitoneum After Gastrostomy Placement in a Patient With Amyotrophic Lateral Sclerosis.

We present a 67-year-old male with amyotrophic lateral sclerosis (ALS) who developed left lower lobe atelectasis and respiratory failure caused by a large pneumoperitoneum after gastrostomy placement. The patient was successfully managed with paracentesis, postural measures, and continued application of noninvasive positive pressure ventilation (NIPPV). There is no clear evidence that links the use of NIPPV with an increased risk of pneumoperitoneum. The evacuation of air from the peritoneal cavity may help improve the respiratory mechanics in patients with diaphragmatic weakness such as the one presented.

Antiparasitic Activity of Compounds Isolated from Ganoderma tuberculosum (Agaricomycetes) from Mexico.

The genus Ganoderma has a long history of use in traditional Asiatic medicine due to its different nutritional and medicinal properties. In Mexico, the species G. tuberculosum is used in indigenous communities, for example, the Wixaritari and mestizos of Villa Guerrero Jalisco for the treatment of diseases that may be related to parasitic infections; however, few chemical studies corroborate its traditional medicinal potential. Thereby, the objective of this study was to isolate and identify anti-parasitic activity compounds from a strain of G. tuberculosum native to Mexico. From the fruiting bodies of G. tuberculosum (GVL-21) a hexane extract was obtained which was subjected to guided fractioning to isolate pure compounds. The in vitro anti-parasitic activity of the pure compound (IC50) was assayed against Leishmania amazonensis, Trypanosoma cruzi, Acanthamoeba castellanii Neff, and Naegleria fowleri. Furthermore, the cytotoxicity (CC50) of the isolated compounds was determined against murine macrophages. The guided fractioning produced 5 compounds: ergosterol (1), ergosta-4,6,8(14),22-tetraen-3-one (2), ergosta-7,22-dien-3ß-ol (3), 3,5-dihydroxy-ergosta-7,22-dien-6-one (4), and ganoderic acid DM (5). Compounds 2 and 5 showed the best anti-parasitic activity in an IC50 range of 54.34 ± 8.02 to 12.38 ± 2.72 µM against all the parasites assayed and low cytotoxicity against murine macrophages. The present study showed for the first time the in vitro anti-parasitic activity of compounds 1-5 against L. amazonensis, T. cruzi, A. castellanii Neff, and N. fowleri, corroborating the medicinal potential of Ganoderma and its traditional applications.

Does substrate matter in the deep sea? A comparison of bone, wood, and carbonate rock colonizers.

Continental margins host methane seeps, animal falls and wood falls, with chemosynthetic communities that may share or exchange species. The goal of this study was to examine the existence and nature of linkages among chemosynthesis-based ecosystems by deploying organic fall mimics (bone and wood) alongside defaunated carbonate rocks within high and lesser levels of seepage activity for 7.4 years. We compared community composition, density, and trophic structure of invertebrates on these hard substrates at active methane seepage and transition (less seepage) sites at Mound 12 at ~1,000 m depth, a methane seep off the Pacific coast of Costa Rica. At transition sites, the community composition on wood and bone was characteristic of natural wood- and whale-fall community composition, which rely on decay of the organic substrates. However, at active sites, seepage activity modified the relationship between fauna and substrate, seepage activity had a stronger effect in defining and homogenizing these communities and they depend less on organic decay. In contrast to community structure, macrofaunal trophic niche overlap between substrates, based on standard ellipse areas, was greater at transition sites than at active sites, except between rock and wood. Our observations suggest that whale- and wood-fall substrates can function as stepping stones for seep fauna even at later successional stages, providing hard substrate for attachment and chemosynthetic food.

Intervention to prevent intestinal parasitic reinfections among Tarahumara indigenous schoolchildren in northern Mexico.

OBJECTIVE: To assess the effectiveness of a 20-week, broad intervention to prevent reinfection by Ascaris lumbricoides (AL) and Giardia lamblia (GL) among indigenous schoolchildren in northern Mexico. METHODS: A prospective, comparative, ecological study. Two isolated boarding schools, each hosting 100-120 children, 4-15 years of age, were selected based on physical infrastructure: intervention school (IS), modern; control school (CS), deprived. After initial diagnosis, children with positive stool samples received supervised treatment with oral nitazoxanide. Diagnoses were made with at least one positive microscopic result from two serial samples using the Faust technique, as reported by the independent observations of two trained, laboratory technicians. Post-treatment samples were taken, and only those with negative results were followed-up. The intervention included infrastructure improvements/maintenance and an educational preventive program for children, parents, and school personnel; no activities were undertaken in the CS. RESULTS: Baseline prevalence for AL was 37.5% at the IS versus 16.6% at the CS (P < 0.01); and for GL, 51.7% versus 37.8%, respectively. At the IS, 35.7% did not speak Spanish, compared to 6.7% in the CS (P < 0.01). Cure rates were similar in both schools for AL (~ 98%) and GL (~ 80%). Final prevalence and reinfection rates for GL were 10.4% versus 10.8%, and 17.2% versus 21% at the IS and CS, respectively. No children were infected/reinfected with AL in either school. Follow-up rates were 80%-83% at the CS and 90%-95% at the IS. CONCLUSIONS: Infection/reinfection rates were similar at the schools after 20 weeks. Supervised treatment alone every semester could effectively control AL/GL infections in this indigenous setting.

Ganoderma oerstedii (Fr.) murrill (higher Basidiomycetes), a tree parasite species in Mexico: taxonomic description, rDNA study, and review of its medical applications.

We present a description of macro- and microscopic taxonomical features of a medicinal mushroom, Ganoderma oerstedii, based on Mexican specimens from the states of Chiapas, Morelos, Sinaloa, and Veracruz, and discuss its relationships with species of the G. lucidum complex. A phylogenetic study based in rDNA sequences of a specimen of G. oerstedii from Veracruz is presented, as well as a review of traditional and modern uses in medicine.

Multi-drug resistant tuberculosis, ten years later. / Tuberculosis multirresistentediez años después.

Drug-resistant tuberculosis, especially those with resistance to rifampicin (RR-TB), has become one of the main obstacles to achieving the dream of eradicating tuberculosis. Furthermore, it is necessary to combine three or four different drugs in the attempt to cure TB, however, unfortunately, there are few available that can be considered genuinely effective. Fortunately, the notable worldwide increase in RR-TB in recent years has led to the investment of resources in the development of new drugs for TB, and other drugs investigated for other diseases have been successfully tested on TB. This has resulted in a clear change in the clinical management of these patients over the last 3-4 years, and it is now easier to design therapeutic regimens and achieve higher success rates. All these changes are updated in this review.

Biological Activities of Different Strains of the Genus Ganoderma spp. (Agaricomycetes) from Mexico.

Antiproliferative, antioxidant, and antibacterial activities were determined for 14 extracts obtained with a mixture of chloroform-methanol (1:1) from the mycelial cultures of 14 wild strains of the genus Ganoderma collected in the central-south part of Veracruz Province, Mexico. Identification of the strains collected was confirmed based on rDNA internal transcribed spacer phylogenetic analysis. The strains G. tuberculosum (GVL-04 and GVL-21), G. tornatum (GVL-05), and G. weberianum (GVL-17 and GVL-26) manifested activity in at least one of the six cancer cell lines tested (HBL-100 and T-47D [breast], HeLa [cervix], A-549 and SW1573 [lung], and WiDr [colon]), with a minimum concentration necessary to cause 50% growth inhibition of cancer cells (GI50) < 50 µg/mL-1. The strains G. tuberculosum (GVL-21) and G. martinicense (GVL-35) had the best antioxidant activity, with values of 62.5 ± 3.9 and 40 ± 2.0 µM Trolox equivalents/mg according to the 1,1-diphenyl-2-picrihydrazyl assay. In addition, nine extracts demonstrated antibacterial activity against Clavibacter michiganensis in a concentration range of 31.5 to 1000 µg/mL. Although these results were expected due to the bioactive potential of Ganoderma species, the antibacterial activity against C. michiganensis causing tomato canker is highlighted.

Antiproliferative and antibacterial activity of extracts of Ganoderma strains grown in vitro.

In this bioprospecting study the biological activities of extracts of the in vitro culture of Ganoderma Mexican strains were evaluated. The extracts were tested by the Sulforhodamine B staining method for antiproliferative activity and the plate microdilution method for antibacterial activity. Extracts that proved bioactive in these two activities, the antioxidant activity (Galvinoxyl, ABTS, and DPPH) and total phenolic contents (Folin-Ciocalteu) were additionally determined, as well as acute toxicity (Artemia franciscana). In the antiproliferative activity Ganoderma curtisii strain (GH-16-015) obtained a remarkable value of GI50 ≤ 50 µg/mL against tumor lines: A549, HBL-100, HeLa, and T-47D. G. curtisii strains (GH-16-012 and GH-16-015) showed MIC values = 500 µg/mL against Staphylococcus aureus. G. curtisii strain (GH-16-012) almost reduced by 50% the radical Galvinoxyl. Finally, G. curtisii strain (GH-16-023) presented the lowest level of toxicity with a LC50 of 490.881 µg/mL against A. franciscana. These results support the potential medicinal effects of Mexican strains of G. curtisii.

The Role of Experience, Perceived Match Importance, and Anxiety on Cortisol Response in an Official Esports Competition.

The aim of the present study was to analyse the neuroendocrine stress response, psychological anxiety response, and perceived match importance (PMI) between expert and non-expert control gamers in an official competitive context. We analyzed, in 25 expert esports players and 20 control participants, modifications in their somatic anxiety, cognitive anxiety, self-confidence, PMI, and cortisol in a League of Legends competition. We found how expert esports players presented higher cortisol concentrations (Z = 155.5; p = 0.03; Cohen's d = -0.66), cognitive anxiety (Z = 99.5; p = 0.001), and PMI (Z = 50.5; p < 0.001) before the competition than non-experts participants. We found a greater statistical weight in the cognitive variables than in the physiological ones. The results obtained suggest that real competitive context and player's expertise were factors associated with an anticipatory stress response. The PMI proved to be a differentiating variable between both groups, highlighting the necessity to include subjective variables that contrast objective measurements.

Extrasynaptic Communication.

Streams of action potentials or long depolarizations evoke a massive exocytosis of transmitters and peptides from the surface of dendrites, axons and cell bodies of different neuron types. Such mode of exocytosis is known as extrasynaptic for occurring without utilization of synaptic structures. Most transmitters and all peptides can be released extrasynaptically. Neurons may discharge their contents with relative independence from the axon, soma and dendrites. Extrasynaptic exocytosis takes fractions of a second in varicosities or minutes in the soma or dendrites, but its effects last from seconds to hours. Unlike synaptic exocytosis, which is well localized, extrasynaptic exocytosis is diffuse and affects neuronal circuits, glia and blood vessels. Molecules that are liberated may reach extrasynaptic receptors microns away. The coupling between excitation and exocytosis follows a multistep mechanism, different from that at synapses, but similar to that for the release of hormones. The steps from excitation to exocytosis have been studied step by step for the vital transmitter serotonin in leech Retzius neurons. The events leading to serotonin exocytosis occur similarly for the release of other transmitters and peptides in central and peripheral neurons. Extrasynaptic exocytosis occurs commonly onto glial cells, which react by releasing the same or other transmitters. In the last section, we discuss how illumination of the retina evokes extrasynaptic release of dopamine and ATP. Dopamine contributes to light-adaptation; ATP activates glia, which mediates an increase in blood flow and oxygenation. A proper understanding of the workings of the nervous system requires the understanding of extrasynaptic communication.