Benthic Primary Production Budget of a Caribbean Reef Lagoon (Puerto Morelos,Mexico)

High photosynthetic benthic primary production (P) represents a key ecosystem service provided by tropical coral reef systems. However, benthic P budgets of specific ecosystem compartments such as macrophyte-dominated reef lagoons are still scarce. To address this, we quantified individual and lagoon-wide net (P_n) and gross (P_g) primary production by all dominant functional groups of benthic primary producers in a typical macrophyte-dominated Caribbean reef lagoon near Puerto Morelos (Mexico) via measurement of O₂ fluxes in incubation experiments. The photosynthetically active 3D lagoon surface area was quantified using conversion factors to allow extrapolation to lagoon-wide P budgets. Findings revealed that lagoon 2D benthic cover was primarily composed of sand-associated microphytobenthos (40%), seagrasses (29%) and macroalgae (27%), while seagrasses dominated the lagoon 3D surface area (84%). Individual P_g was highest for macroalgae and scleractinian corals (87 and 86 mmol O₂ m⁻² specimen area d⁻¹, respectively), however seagrasses contributed highest (59%) to the lagoon-wide P_g. Macroalgae exhibited highest individual P_n rates, but seagrasses generated the largest fraction (51%) of lagoon-wide P_n. Individual R was highest for scleractinian corals and macroalgae, whereas seagrasses again provided the major lagoon-wide share (68%). These findings characterise the investigated lagoon as a net autotrophic coral reef ecosystem compartment revealing similar P compared to other macrophyte-dominated coastal environments such as seagrass meadows and macroalgae beds. Further, high lagoon-wide P (P_g: 488 and P_n: 181 mmol O₂ m⁻² lagoon area d⁻¹) and overall P_g:R (1.6) indicate substantial benthic excess production within the Puerto Morelos reef lagoon and suggest the export of newly synthesised organic matter to surrounding ecosystems.     

Evidence That Transition from Health to Psychotic Disorder Can Be Traced to Semi-Ubiquitous Environmental Effects Operating against Background Genetic Risk

Background

In order to assess the importance of environmental and genetic risk on transition from health to psychotic disorder, a prospective study of individuals at average (n = 462) and high genetic risk (n = 810) was conducted.

Method

A three-year cohort study examined the rate of transition to psychotic disorder. Binary measures indexing environmental exposure (combining urban birth, cannabis use, ethnicity and childhood trauma) and proxy genetic risk (high-risk sibling status) were used to model transition.

Results

The majority of high-risk siblings (68%) and healthy comparison subjects (60%) had been exposed to one or more environmental risks. The risk of transition in siblings (n = 9, 1.1%) was higher than the risk in healthy comparison subjects (n = 2, 0.4%; OR_adj  = 2.2,95%CI:5–10.3). All transitions (100%) were associated with environmental exposure, compared to 65% of non-transitions (p = 0.014), with the greatest effects for childhood trauma (OR_adj  = 34.4,95%CI:4.4–267.4), cannabis use (OR = 4.1,95%CI:1.1, 15.4), minority ethnic group (OR = 3.8,95%CI:1.2,12.8) and urban birth (OR = 3.7,95%CI:0.9,15.4). The proportion of transitions in the population attributable to environmental and genetic risk ranged from 28% for minority ethnic group, 45% for urban birth, 57% for cannabis use, 86% for childhood trauma, and 50% for high-risk sibling status. Nine out of 11 transitions (82%) were exposed to both genetic and environmental risk, compared to only 43% of non-transitions (p = 0.03).

Conclusion

Environmental risk associated with transition to psychotic disorder is semi-ubiquitous regardless of genetic high risk status. Careful prospective documentation suggests most transitions can be attributed to powerful environmental effects that become detectable when analysed against elevated background genetic risk, indicating gene-environment interaction.     

Dual-function RNA regulators in bacteria

The importance of small RNA (sRNA) regulators has been recognized across all domains of life. In bacteria, sRNAs typically control the expression of virulence and stress response genes via antisense base pairing with mRNA targets. Originally dubbed “non-coding RNAs,” a number of bacterial antisense sRNAs have been found to encode functional proteins. Although very few of these dual-function sRNAs have been characterized, they have been found in both gram-negative and gram-positive organisms. Among the few known examples, the functions and mechanisms of regulation by dual-function sRNAs are variable. Some dual-function sRNAs depend on the RNA chaperone Hfq for base pairing-dependent regulation (riboregulation); this feature appears so far exclusive to gram-negative bacterial sRNAs. Other variations can be found in the spatial organization of the coding region with respect to the riboregulation determinants. How the functions of encoded proteins relate to riboregulation is for the most part not understood. However, in one case it appears that there is physiological redundancy between protein and riboregulation functions. This mini-review focuses on the two best-studied bacterial dual-function sRNAs: RNAIII from Staphylococcus aureus and SgrS from Escherichia coli and includes a discussion of what is known about the structure, function and physiological roles of these sRNAs as well as what questions remain outstanding.     

The chromosomal passenger complex controls spindle checkpoint function independent from its role in correcting microtubule kinetochore interactions

The chromosomal passenger complex (CPC) is a critical regulator of chromosome segregation during mitosis by correcting nonbipolar microtubule-kinetochore interactions. By severing these interactions, the CPC is thought to create unattached kinetochores that are subsequently sensed by the spindle assembly checkpoint (SAC) to prevent premature mitotic exit. We now show that spindle checkpoint function of the CPC and its role in eliminating nonbipolar attachments can be uncoupled. Replacing the chromosomal passenger protein INCENP with a mutant allele that lacks its coiled-coil domain results in an overt defect in a SAC-mediated mitotic arrest in response to taxol treatment, indicating that this domain is critical for CPC function in spindle checkpoint control. Surprisingly, this mutant could restore alignment and cytokinesis during unperturbed cell divisions and was capable of resolving syntelic attachments. Also, Aurora-B kinase was localized and activated normally on centromeres in these cells, ruling out a role for the coiled-coil domain in general Aurora-B activation. Thus, mere microtubule destabilization of nonbipolar attachments by the CPC is insufficient to install a checkpoint-dependent mitotic arrest, and additional, microtubule destabilization-independent CPC signaling toward the spindle assembly checkpoint is required for this arrest, potentially through amplification of the unattached kinetochore-derived checkpoint signal.     

Effects of taxon sampling and tree reconstruction methods on phylodiversity metrics

相似文献   

Prehospital electronic patient care report systems: early experiences from emergency medical services agency leaders

Background

As the United States embraces electronic health records (EHRs), improved emergency medical services (EMS) information systems are also a priority; however, little is known about the experiences of EMS agencies as they adopt and implement electronic patient care report (e-PCR) systems. We sought to characterize motivations for adoption of e-PCR systems, challenges associated with adoption and implementation, and emerging implementation strategies.

Methods

We conducted a qualitative study using semi-structured in-depth interviews with EMS agency leaders. Participants were recruited through a web-based survey of National Association of EMS Physicians (NAEMSP) members, a didactic session at the 2010 NAEMSP Annual Meeting, and snowball sampling. Interviews lasted approximately 30 minutes, were recorded and professionally transcribed. Analysis was conducted by a five-person team, employing the constant comparative method to identify recurrent themes.

Results

Twenty-three interviewees represented 20 EMS agencies from the United States and Canada; 14 EMS agencies were currently using e-PCR systems. The primary reason for adoption was the potential for e-PCR systems to support quality assurance efforts. Challenges to e-PCR system adoption included those common to any health information technology project, as well as challenges unique to the prehospital setting, including: fear of increased ambulance run times leading to decreased ambulance availability, difficulty integrating with existing hospital information systems, and unfunded mandates requiring adoption of e-PCR systems. Three recurring strategies emerged to improve e-PCR system adoption and implementation: 1) identify creative funding sources; 2) leverage regional health information organizations; and 3) build internal information technology capacity.

Conclusion

EMS agencies are highly motivated to adopt e-PCR systems to support quality assurance efforts; however, adoption and implementation of e-PCR systems has been challenging for many. Emerging strategies from EMS agencies and others that have successfully implemented EHRs may be useful in expanding e-PCR system use and facilitating this transition for other EMS agencies.