Lessons from the historical dynamics of environmental law enforcement in the Brazilian Amazon.

Here, we analyze critical changes in environmental law enforcement in the Brazilian Amazon between 2000 and 2020. Based on a dataset of law enforcement indicators, we discuss how these changes explain recent Amazon deforestation dynamics. Our analysis also covers changes in the legal prosecution process and documents a militarization of enforcement between 2018 and 2022. From 2004 to 2018, 43.6 thousand land-use embargoes and 84.3 thousand fines were issued, targeting 3.3 million ha of land, and totaling USD 9.3 billion in penalties. Nevertheless, enforcement relaxed and became spatially more limited, signaling an increasing lack of commitment by the State to enforcing the law. The number of embargoes and asset confiscations dropped by 59% and 55% in 2019 and 2020, respectively. These changes were accompanied by a marked increase in enforcement expenditure, suggesting a massive efficiency loss. More importantly, the creation of so-called conciliation hearings and the centralization of legal processes in 2019 reduced the number of actual judgments and fines collected by 85% and decreased the ratio between lawsuits resulting in paid fines over filed ones from 17 to 5%. As Brazil gears up to crack-down on illegal deforestation once again, our assessment suggests urgent entry points for policy action.

Will farmers seek environmental regularization in the Amazon and how? Insights from the Rural Environmental Registry (CAR) questionnaires.

The future availability and quality of natural resources essential to life such as ecosystem services and biodiversity depend on the conservation and restoration of native vegetation. The Brazilian Native Vegetation Protection Law (NVPL) requires farmers to conserve a minimum percentage of native vegetation within their properties as Legal Reserves (LR) as well as riparian forests and hilltops as Permanent Preservation Areas (PPAs). To monitor the conservation and facilitate the compliance of these areas, the Rural Environmental Registry (CAR) and the Environmental Regularization Program (PRA) were created. However, so far, little is known about farmers' interest in joining the PRA and the actions they intend to take to correct their past illegal deforestation. This article explores a unique dataset comprising of the individual answers of 97 thousand farmers in the states of Pará and Mato Grosso given to the Brazilian Forest Service in the process of joining at the national rural environmental registry system. We found that the adherence to the PRA is positively correlated with recognition of the LR deficit and the size of the rural property. Also medium and large landowners and crop producers tend to seek compliance by taking actions outside the farm (compensation), while small farmers and squatters are more likely to act inside their own areas (restoration). Understanding farmers' interests and options for LR compliance can contribute for the formulation of more effective implementation strategies for PRA and NVPL.

Disease risk analysis in sea turtles: A baseline study to inform conservation efforts.

The impact of a range of different threats has resulted in the listing of six out of seven sea turtle species on the IUCN Red List of endangered species. Disease risk analysis (DRA) tools are designed to provide objective, repeatable and documented assessment of the disease risks for a population and measures to reduce these risks through management options. To the best of our knowledge, DRAs have not previously been published for sea turtles, although disease is reported to contribute to sea turtle population decline. Here, a comprehensive list of health hazards is provided for all seven species of sea turtles. The possible risk these hazards pose to the health of sea turtles were assessed and "One Health" aspects of interacting with sea turtles were also investigated. The risk assessment was undertaken in collaboration with more than 30 experts in the field including veterinarians, microbiologists, social scientists, epidemiologists and stakeholders, in the form of two international workshops and one local workshop. The general finding of the DRA was the distinct lack of knowledge regarding a link between the presence of pathogens and diseases manifestation in sea turtles. A higher rate of disease in immunocompromised individuals was repeatedly reported and a possible link between immunosuppression and environmental contaminants as a result of anthropogenic influences was suggested. Society based conservation initiatives and as a result the cultural and social aspect of interacting with sea turtles appeared to need more attention and research. A risk management workshop was carried out to acquire the insights of local policy makers about management options for the risks relevant to Queensland and the options were evaluated considering their feasibility and effectiveness. The sea turtle DRA presented here, is a structured guide for future risk assessments to be used in specific scenarios such as translocation and head-starting programs.

Potential Impact of Construction Noise on Selected Zoo Animals.

In anticipation of a major construction project in an urban New Zealand zoo, a study was initiated to assess the response to construction noise of selected animal species (elephant, giraffe, emu and alligator) previously observed to be sensitive to this kind of noise. The overall aim was to detect any signs of aversive responses to this noise to enable keepers to recognize these and take any necessary mitigating actions during the construction period. The experimental approach involved the creation of acoustic maps of each focal animal enclosure, a series of 90-min video recordings of the animals' behavior in response to ambient noise (control) and amplified broadcast of pre-recorded continuous and intermittent construction noise. Concentration of fecal corticosterone metabolites was also measured for the emus. Key findings were that giraffes, elephants and emus appeared to show an increase in behaviors that could indicate stress or agitation including vigilance and locomotion and may prefer quieter regions of their enclosure during sound exposure. Giraffes also increased close contact with conspecifics when exposed to construction noise. While alligators did not show clear evidence of noise-related stress, our findings indicated that all focal species showed some behavioral responses to recorded construction noise.

Blending Polymer Labile Elements at Differing Scales to Affect Degradation Profiles in Heart Valve Scaffolds.

After more than 22 years of research challenges and innovation, the heart valve tissue engineering paradigm still attracts attention as an approach to overcome limitations which exist with clinically utilized mechanical or bioprosthetic heart valves. Despite encouraging results, delayed translation can be attributed to limited knowledge on the concurrent mechanisms of biomaterial degradation in vivo, host inflammatory response, cell recruitment, and de novo tissue elaboration. This study aimed to reduce this gap by evaluating three alternative levels at which lability could be incorporated into candidate polyurethane materials electroprocessed into a valve scaffold. Specifically, polyester and polycarbonate labile soft segment diols were reacted into thermoplastic elastomeric polyurethane ureas that formed scaffolds where (1) a single polyurethane containing both of the two diols in the polymer backbone was synthesized and processed, (2) two polyurethanes were physically blended, one with exclusively polycarbonate and one with exclusively polyester diols, followed by processing of the blend, and (3) the two polyurethane types were concurrently processed to form individual fiber populations in a valve scaffold. The resulting valve scaffolds were characterized in terms of their mechanics before and after exposure to varying periods of pulsatile flow in an enzymatic (lipase) buffer solution. The results showed that valve scaffolds made from the first type of polymer and processing combination experienced more extensive degradation. This approach, although demonstrated with polyurethane scaffolds, can generally be translated to investigate biomaterial approaches where labile elements are introduced at different structural levels to alter degradation properties while largely preserving the overall chemical composition and initial mechanical behavior.

The Investigation into the Toxic Potential of Iron Oxide Nanoparticles Utilizing Rat Pheochromocytoma and Human Neural Stem Cells.

Magnetic iron oxide (Magnetite, Fe3O4) nanoparticles are widely utilized in magnetic resonance imaging (MRI) and drug delivery applications due to their superparamagnetism. Surface coatings are often employed to change the properties of the magnetite nanoparticles or to modulate their biological responses. In this study, magnetite nanoparticles were fabricated through hydrothermal synthesis. Hydrophobicity is often increased by surface modification with oleic acid. In this study, however, hydrophobicity was introduced through surface modification with n-octyltriethoxysilane. Both the uncoated (hydrophilic) and coated (hydrophobic) individual nanoparticle sizes measured below 20 nm in diameter, a size range in which magnetite nanoparticles exhibit superparamagnetism. Both types of nanoparticles formed aggregates which were characterized by SEM, TEM, and dynamic light scattering (DLS). The coating process significantly increased both individual particle diameter and aggregate sizes. We tested the neurotoxicity of newly synthesized nanoparticles with two mammalian cell lines, PC12 (rat pheochromocytoma) and ReNcell VM (human neural stem cells). Significant differences were observed in cytotoxicity profiles, which suggests that the cell type (rodent versus human) or the presence of serum matters for nanoparticle toxicology studies. Differences in nanoparticle associations/uptake between the two cell types were observed with Prussian Blue staining. Finally, safe concentrations which did not significantly affect neuronal differentiation profiles were identified for further development of the nanoparticles.

Meso-scale topological cues influence extracellular matrix production in a large deformation, elastomeric scaffold model.

Physical cues are decisive factors in extracellular matrix (ECM) formation and elaboration. Their transduction across scale lengths is an inherently symbiotic phenomenon that while influencing ECM fate is also mediated by the ECM structure itself. This study investigates the possibility of enhancing ECM elaboration by topological cues that, while not modifying the substrate macro scale mechanics, can affect the meso-scale strain range acting on cells incorporated within the scaffold. Vascular smooth muscle cell micro-integrated, electrospun scaffolds were fabricated with comparable macroscopic biaxial mechanical response, but different meso-scale topology. Seeded scaffolds were conditioned on a stretch bioreactor and exposed to large strain deformations. Samples were processed to evaluate ECM quantity and quality via: biochemical assay, qualitative and quantitative histological assessment and multi-photon analysis. Experimental evaluation was coupled to a numerical model that elucidated the relationship between the scaffold micro-architecture and the strain acting on the cells. Results showed an higher amount of ECM formation for the scaffold type characterized by lowest fiber intersection density. The numerical model simulations associated this result with the differences found for the change in cell nuclear aspect ratio and showed that given comparable macro scale mechanics, a difference in material topology created significant differences in cell-scaffold meso-scale deformations. These findings reaffirmed the role of cell shape in ECM formation and introduced a novel notion for the engineering of cardiac tissue where biomaterial structure can be designed to both mimick the organ level mechanics of a specific tissue of interest and elicit a desirable cellular response.

Nitro-Oleic Acid (NO2-OA) Release Enhances Regional Angiogenesis in a Rat Abdominal Wall Defect Model.

Ventral hernia is often addressed surgically by the placement of prosthetic materials, either synthetic or from allogeneic and xenogeneic biologic sources. Despite advances in surgical approaches and device design, a number of postsurgical limitations remain, including hernia recurrence, mesh encapsulation, and reduced vascularity of the implanted volume. The in situ controlled release of angiogenic factors from a scaffold facilitating abdominal wall repair might address some of these issues associated with suboptimal tissue reconstruction. Furthermore, a biocomposite material that combines the favorable mechanical properties achievable with synthetic materials and the bioactivity associated with xenogeneic tissue sources would be desirable. In this report, an abdominal wall repair scaffold has been designed based on a microfibrous, elastomeric poly(ester carbonate)urethane urea matrix integrated with a hydrogel derived from decellularized porcine dermis (extracellular matrix [ECM] gel) and poly(lactic-co-glycolic acid) (PLGA) microspheres loaded with nitro-oleic acid (NO2-OA). NO2-OA is an electrophilic fatty acid nitro-alkene derivative that, under hypoxic conditions, induces angiogenesis. This scaffold was utilized to repair a rat abdominal wall partial thickness defect, hypothesizing that the nitro-fatty acid release would facilitate increased angiogenesis at the 8-week endpoint. The quantification of neovascularization was conducted by novel methodologies to assess vessel morphology and spatial distribution. The repaired abdominal wall defects were evaluated by histopathologic methods, including quantification of the foreign body response and cellular ingrowth. The results showed that NO2-OA release was associated with significantly improved regional angiogenesis. The combined biohybrid scaffold and NO2-OA-controlled release strategy also reduced scaffold encapsulation, increased wall thickness, and enhanced cellular infiltration. More broadly, the three components of the composite scaffold design (ECM gel, polymeric fibers, and PLGA microparticles) enable the tuning of performance characteristics, including scaffold bioactivity, degradation, mechanics, and drug release profile, all decisive factors to better address current limitations in abdominal wall repair or other soft tissue augmentation procedures.

Sustained viral gene delivery from a micro-fibrous, elastomeric cardiac patch to the ischemic rat heart.

Biodegradable and elastomeric patches have been applied to the surface of infarcted hearts as temporary mechanical supports to effectively alter adverse left ventricular remodeling processes. In this report, recombinant adeno-associated virus (AAV), known for its persistent transgene expression and low pathogenicity, was incorporated into elastomeric polyester urethane urea (PEUU) and polyester ether urethane urea (PEEUU) and processed by electrospinning into two formats (solid fibers and core-sheath fibers) designed to influence the controlled release behavior. The extended release of AAV encoding green fluorescent protein (GFP) was assessed in vitro. Sustained and localized viral particle delivery was achieved over 2 months in vitro. The biodegradable cardiac patches with or without AAV-GFP were implanted over rat left ventricular lesions three days following myocardial infarction to evaluate the transduction effect of released viral vectors. AAV particles were directly injected into the infarcted hearts as a control. Cardiac function and remodeling were significantly improved for 12 weeks after patch implantation compared to AAV injection. More GFP genes was expressed in the AAV patch group than AAV injection group, with both α-SMA positive cells and cardiac troponin T positive cells transduced in the patch group. Overall, the extended release behavior, prolonged transgene expression, and elastomeric mechanical properties make the AAV-loaded scaffold an attractive option for cardiac tissue engineering where both gene delivery and appropriate mechanical support are desired.

A Comparison of Disease Risk Analysis Tools for Conservation Translocations.

Conservation translocations are increasingly used to manage threatened species and restore ecosystems. Translocations increase the risk of disease outbreaks in the translocated and recipient populations. Qualitative disease risk analyses have been used as a means of assessing the magnitude of any effect of disease and the probability of the disease occurring associated with a translocation. Currently multiple alternative qualitative disease risk analysis packages are available to practitioners. Here we compare the ease of use, expertise required, transparency, and results from, three different qualitative disease risk analyses using a translocation of the endangered New Zealand passerine, the hihi (Notiomystis cincta), as a model. We show that the three methods use fundamentally different approaches to define hazards. Different methods are used to produce estimations of the risk from disease, and the estimations are different for the same hazards. Transparency of the process varies between methods from no referencing, or explanations of evidence to justify decisions, through to full documentation of resources, decisions and assumptions made. Evidence to support decisions on estimation of risk from disease is important, to enable knowledge acquired in the future, for example, from translocation outcome, to be used to improve the risk estimation for future translocations. Information documenting each disease risk analysis differs along with variation in emphasis of the questions asked within each package. The expertise required to commence a disease risk analysis varies and an action flow chart tailored for the non-wildlife health specialist are included in one method but completion of the disease risk analysis requires wildlife health specialists with epidemiological and pathological knowledge in all three methods. We show that disease risk analysis package choice may play a greater role in the overall risk estimation of the effect of disease on animal populations involved in a translocation than might previously have been realised.

Bi-layered polyurethane - Extracellular matrix cardiac patch improves ischemic ventricular wall remodeling in a rat model.

As an intervention to abrogate ischemic cardiomyopathy, the concept of applying a temporary, local patch to the surface of the recently infarcted ventricle has been explored from a number of design perspectives. Two important features considered for such a cardiac patch include the provision of appropriate mechanical support and the capacity to influence the remodeling pathway by providing cellular or biomolecule delivery. The objective of this report was to focus on these two features by first evaluating the incorporation of a cardiac extracellular matrix (ECM) component, and second by evaluating the impact of patch anisotropy on the pathological remodeling process initiated by myocardial infarction. The functional outcomes of microfibrous, elastomeric, biodegradable cardiac patches have been evaluated in a rat chronic infarction model. Ten weeks after infarction and 8 wk after patch epicardial placement, echocardiographic function, tissue-level structural remodeling (e.g., biaxial mechanical response and microstructural analysis), and cellular level remodeling were assessed. The results showed that the incorporation of a cardiac ECM altered the progression of several keys aspects of maladaptive remodeling following myocardial infarction. This included decreasing LV global mechanical compliance, inhibiting echocardiographically-measured functional deterioration, mitigating scar formation and LV wall thinning, and promoting angiogenesis. In evaluating the impact of patch anisotropy, no effects from the altered patch mechanics were detected after 8 wk, possibly due to patch fibrous encapsulation. Overall, this study demonstrates the benefit of a cardiac patch design that combines both ventricle mechanical support, through a biodegradable, fibrillary elastomeric component, and the incorporation of ECM-based hydrogel components.

Emerging infectious disease or evidence of endemicity? A multi-season study of beak and feather disease virus in wild red-crowned parakeets (Cyanoramphus novaezelandiae).

Beak and feather disease virus (BFDV) is a single-stranded DNA virus that is the etiological agent of beak and feather disease in both wild and captive parrots. Given that BFDV is globally recognized as a conservation threat for wild parrots, between 2011-2013, red-crowned parakeets (Cyanoramphus novaezelandiae, n = 229), which are endemic to New Zealand, were captured in mist nets on Tiritiri Matangi Island and Hauturu-o-Toi/Little Barrier Island (LBI), New Zealand, for disease surveillance. Blood and feathers from all birds were tested by PCR for BFDV, and full genomes were recovered and sequenced. A subset of blood samples (n = 96) were tested for antibodies to BFDV by the haemagglutination inhibition (HI) test. A further 238 feather samples were obtained from red-crowned parakeets from three sites in the Wellington region of the North Island, and these were screened for BFDV. The DNA-based prevalence of BFDV infection determined on Tiritiri Matangi Island was 1.09% (CI 95 %, 0.1-3.9%); on Hauturu-o-Toi/LBI, 4.4% (95% CI, 0.5%-15.1%); on Kapiti Island, 3.4% (CI 95%, 1.1-7.8%); at the ZEALANDIA-Karori sanctuary, 1.6% (95% CI, 0-8.4%); and on Matiu-Somes Island, 0% (CI 95%, 0-12.3%). Seroprevalence for BFDV, indicating prior or current exposure, in the Tiritiri Matangi Island population, it was 2% (CI 95%, 0-10.1%), and in the Hauturu-o-Toi/LBI population was 14% (CI 95%, 5.3-27.9%). BFDV-positive birds showed no signs of clinical disease, with the exception of an individual bird obtained opportunistically from Shakespear Regional Park during the study period, which had classical signs of feather loss. Phylogenetic analysis of the 11 full genome sequences recovered from BFDV-positive red-crowned parakeets revealed evidence of ongoing viral flow between red-crowned parakeets and eastern rosellas (Platycercus eximius) in the Hauraki Gulf/Auckland region, with separate but closely related strains from the Wellington region of the North Island. This is the first study to report HI results for a New Zealand endemic parrot species, and the first epidemiological analysis of serial cross-sectional surveys in a BFDV-infected population of red-crowned parakeets in New Zealand. We postulate that although BFDV remains a threat to small, isolated or naïve populations of parrots globally, the low viral prevalence in this and other studies suggests that native parakeets in New Zealand may act as dead-end or spillover hosts.

KNEMIDOKOPTINID (EPIDERMOPTIDAE: KNEMIDOKOPTINAE) MITE INFESTATION IN WILD RED-CROWNED PARAKEETS (CYANORAMPHUS NOVAEZELANDIAE): CORRELATIONS BETWEEN MACROSCOPIC AND MICROSCOPIC FINDINGS.

During a study on health and disease in Red-crowned Parakeets (Cyanoramphus novaezelandiae) on Tiritiri Matangi Island and Little Barrier Island (Hauturu-o-Toi) in New Zealand between 2011 and 2013, an outbreak of feather loss prompted the collection of skin biopsies (n = 135) under anesthesia from the head of captured birds. A subset of samples (n = 7) was frozen to obtain whole specimens for identification of ectoparasites. Mites (range 1-11) were observed in 79/135 (58.5%) skin biopsies, whereas feather loss was only found in 47/142 (33.1%) birds captured during the sampling period. Compact orthokeratotic hyperkeratosis and acanthosis were found in association with mites. Procnemidocoptes janssensi (Acari: Epidermoptidae, Knemidokoptinae) was identified from whole mites obtained from skin biopsies. We describe the presence, pathology, and stages of infestation for knemidokoptinid mange in a wild parrot population in New Zealand. Given the clinical and pathologic changes observed and poor knowledge of the parasite's New Zealand host and geographic distribution, further work is recommended for this and sympatric parrots, to understand relationships between the host, parasite, environment, and expression of disease. Results from this study reinforce the value of including biopsy samples for the investigation of skin disease in wild birds, particularly to link etiologic agents with pathologic changes.

Surveillance for arboviral zoonoses in New Zealand birds.

INTRODUCTION: Given the significant burden that emerging infectious diseases place on global economies and public health, the monitoring and mitigation of, and early response to, potential infectious diseases are of the highest priority. The objective of this study was to survey for known and other potential arboviral zoonoses in multiple bird species at four locations in New Zealand. METHODS: Common bird species were targeted for blood sampling during two southern hemisphere summers. Sera from each period (n = 185 and n = 693) were screened in an epitope blocking enzyme immunoassay for flavivirus antibody detection. In the first season, testing for antibodies to specific alphaviruses was conducted on samples with sufficient sera (n = 22). In the second season, blood clots (n = 544) were screened for viral presence by polymerase chain reaction (PCR) for alphaviral and flaviviral RNA, and virus isolation (n = 146) was conducted. RESULTS: Flavivirus antibodies were detected in 13 species, and one Australasian gannet (Morus serrator) from one site was positive for antibodies to Ross River virus. PCR tests and virus isolation were all negative. DISCUSSION: Evidence for flavivirus exposure in seabirds at Kaikoura Peninsula and Cape Kidnappers suggests that viruses isolated from seabirds and associated ticks in New Zealand in the late 1970s are still present. Evidence for flavivirus exposure in passerines at Kaikoura Peninsula, Cape Kidnappers and Mokoia Island is novel. The Ross River virus finding is also new and supports the hypothesis that migratory seabirds are an import pathway for such agents into New Zealand.

Fluorosis as a probable factor in metabolic bone disease in captive New Zealand native frogs (Leiopelma species).

This report describes the investigations into the cause and treatment of metabolic bone disease (MBD) in captive native New Zealand frogs (Leiopelma spp.) and the role of fluoride in the disease. MBD was diagnosed in Leiopelma archeyi and Leiopelma hochstetteri in 2008 at three institutions: Auckland Zoo, Hamilton Zoo, and the University of Otago. Most of these frogs had originally been held at the University of Canterbury for several years (2000-2004) but some were collected directly from the wild. Radiographs on archived and live frogs showed that MBD had been present at Canterbury, but at a lower rate (3%) than in the current institutions (38-67%). Microcomputed tomography showed that the femoral diaphyses of the captive frogs at Auckland Zoo had greater bone volume, bone surface, cross-sectional thickness, and mean total cross-sectional bone perimeter, which is consistent with osteofluorosis. On histology of the same femurs, there was hyperplasia, periosteal growth, and thickening of trabeculae, which are also consistent with skeletal fluorosis. An increase in fluoride levels in the water supply preceded the rise in the incidence of the above pathology, further supporting the diagnosis of osteofluorosis. Analysis of long-standing husbandry practices showed that ultraviolet B (UVB) exposure and the dietary calcium:phosphorus ratio were deficient when compared with wild conditions-likely causing chronic underlying MBD. To prevent multifactorial MBD in captive Leiopelma, the authors recommend increasing dietary calcium by incorporating into the captive diet inherently calcium-rich invertebrates; increasing exposure to natural or artificial (UVB) light; and using defluoridated water. Addressing these three factors at Auckland Zoo reduced morbidity, bone fractures, and mortality rates.

Nematode and ciliate nasal infection in captive archey's frogs (Leiopelma archeyi).

Archey's frogs (Leiopelma archeyi) are first on the list of evolutionarily distinct and globally endangered (EDGE) amphibians. Captive breeding is an important strategy for protection of the species, but programs are hampered by a lack of information on diseases present in wild and captive populations. Two novel nematodes (Koerneria sp. and Rhabditis sp.) were found separately in four captive Archey's frogs showing clinical signs of hemorrhagic purulent nasal discharge and weight loss. One of these frogs also had a novel protozoal infection (Tetrahymena) in the nasal cavity. Koerneria, Rhabditis, and Tetrahymena have not previously been reported in amphibians in New Zealand. One frog was treated successfully with oral moxidectin at 0.4 mg/kg for the nematode infection and topical metronidazole at 10 mg/kg for the protozoal infection. The clinical signs abated only after both infections were cleared. The second frog died before treatment could be established. The third and fourth frogs were found dead.

Transition state of the sulfuryl transfer reaction of estrogen sulfotransferase.

Kinetic isotope effects have been measured for the estrogen sulfotransferase-catalyzed sulfuryl (SO3) transfer from p-nitrophenyl sulfate to the 5'-phosphoryl group of 3'-phosphoadenosine 5'-phosphate. 18(V/K)nonbridge = 1.0016 +/- 0.0005, 18(V/K)bridge = 1.0280 +/- 0.0006, and 15(V/K) = 1.0014 +/- 0.0004. (15(V/K) refers to the nitro group in p-nitrophenyl sulfate). The kinetic isotope effects indicate substantial S O bond fission in the transition state, with partial charge neutralization of the leaving group. The small kinetic isotope effect in the nonbridging sulfuryl oxygen atoms suggests no significant change in bond orders of these atoms occurs, consistent with modest nucleophilic involvement. A comparison of the data for enzymatic and uncatalyzed sulfuryl transfer reactions suggests that both proceed through very similar transition states.

Generality of solvation effects on the hydrolysis rates of phosphate monoesters and their possible relevance to enzymatic catalysis.

Previous work by Kirby and co-workers revealed a significant acceleration of the rate of hydrolysis of p-nitrophenyl phosphate by added dipolar solvents such as DMSO. Activation parameters and kinetic isotope effects have been measured to ascertain the origin of this effect. The generality of this phenomenon was examined with a series of esters with more basic leaving groups. Computational analyses of the effects of desolvation of dianionic phosphate monoesters were carried out, and the possible effect of the transfer from water to the active site of alkaline phosphatase was modeled. The results are consistent with a desolvation-induced weakening of the P-O ester bond in the ground state. Other aryl phosphate esters show similar rate accelerations at high fractions of DMSO, but phenyl and methyl phosphates do not, and their hydrolysis reactions are actually slowed by these conditions.