Regrowth Potential Research Articles

Multiple views of biological stability and optimized coagulation in the control of biostability in traditional water treatment processes: a pilot test

This study investigated biological stability in a pilot test of traditional water treatment processes in eastern China. The variations of assimilable organic carbon, biodegradable dissolved organic carbon, bacterial regrowth potential, and total phosphorus were analyzed, and the relationships among them were studied. High-purity aluminum sulfate was added as a coagulant, and the corresponding removal efficiencies of the coagulation–sedimentation unit and the sand filtration unit were evaluated. The experimental results indicate that the removal efficiencies of the dissolved organic carbon (DOC) and UV254 both increased as the alum dosages increased in the coagulation and sedimentation process. The removal efficiencies of the biostability indicators of the coagulation and sedimentation process were higher than those of the filtration treatment. The bacterial regrowth potential was correlated with DOC concentration, and the introduction of total dissolved phosphorus into the evaluation of biostability is recommended to help confirm the C:P ratio and to select the appropriate strategy for controlling bacterial regrowth. An explanation for the changes in biostability indicators is provided.

Slow recovery of tropical old-field rainforest regrowth and the value and limitations of active restoration.

There is current debate about the potential for secondary regrowth to rescue tropical forests from an otherwise inevitable cascade of biodiversity loss due to land clearing and scant evidence to test how well active restoration may accelerate recovery. We used site chronosequences to compare developmental trajectories of vegetation between self-organized (i.e., spontaneous) forest regrowth and biodiversity plantings (established for ecological restoration, with many locally native tree species at high density) in the Australian wet tropics uplands. Across 28 regrowth sites aged 1-59 years, some structural attributes reached reference rainforest levels within 40 years, whereas wood volume and most tested components of native plant species richness (classified by species' origins, family, and ecological functions) reached less than 50% of reference rainforest values. Development of native tree and shrub richness was particularly slow among species that were wind dispersed or animal dispersed with large (>10 mm) seeds. Many species with animal-dispersed seeds were from near-basal evolutionary lineages that contribute to recognized World Heritage values of the study region. Faster recovery was recorded in 25 biodiversity plantings of 1-25 years in which wood volume developed more rapidly; native woody plant species richness reached values similar to reference rainforest and was better represented across all dispersal modes; and species from near-basal plant families were better (although incompletely) represented. Plantings and regrowth showed slow recovery in species richness of vines and epiphytes and in overall resemblance to forest in species composition. Our results can inform decision making about when and where to invest in active restoration and provide strong evidence that protecting old-growth forest is crucially important for sustaining tropical biodiversity.

Influence of water quality on nitrifier regrowth in two full-scale drinking water distribution systems.

The potential for regrowth of nitrifying microorganisms was monitored in 2 full-scale chloraminated drinking water distribution systems in Ontario, Canada, over a 9-month period. Quantitative PCR was used to measure amoA genes from ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), and these values were compared with water quality parameters that can influence nitrifier survival and growth, including total chlorine, ammonia, temperature, pH, and organic carbon. Although there were no severe nitrification episodes, AOB and AOA were frequently detected at low concentrations in samples collected from both distribution systems. A culture-based presence-absence test confirmed the presence of viable nitrifiers. AOB were usually present in similar or greater numbers than AOA in both systems. As well, AOB showed higher regrowth potential compared with AOA in both systems. Statistically significant correlations were measured between several water quality parameters of relevance to nitrification. Total chlorine was negatively correlated with both nitrifiers and heterotrophic plate count (HPC) bacteria, and ammonia levels were positively correlated with nitrifiers. Of particular importance was the strong correlation between HPC and AOB, which reinforced the usefulness of HPC as an operational parameter to measure general microbiological conditions in distribution systems.

Regrowth in post-fire area in a fragment of semideciduous seasonal forest in Viçosa-MG

The sprouting is the typical response of pointers to death of trees as a result of fire, courts, diseases or physiological disorders. The present work aimed to study the regrowth ability of species remaining trees in a Seasonal Forest Semidecidual degraded by fire and assess the importance of resprouting ability in the area of recovery. The fire resulted in the destruction of 12 hectares of native vegetation, with differential levels of degradation. The study focused on the section where the effect of the fire was more severe, with total destruction of the vegetation cover. The area a complete survey of all species showing budding was performed. The diameter (cm) at the base of the bud, using a caliper, and the height (m) of the sprout with the aid of a tape was measured. It was observed that the sprouting capacity varies with the tree species and the size/age of the plant. Mabea fistulifera and Dalbergia nigra showed a higher number of shoots; Anadenanthera macrocarpa and Piptadenia gonoacantha the greatest height and diameter, the first of which also had the highest number of shoots per array; Aegiphila sellowiana showed high potential for regrowth both the stem and the roots. The widespread occurrence of grasses, especially the grass ( Melinis minutiflora ) represents a physical impediment and reduces the brightness to the by sprouting roots. Additional keywords: budding; forest fire; natural regeneration; secondary succession.

Pratt timothy

Papadopoulos, Y. A., Christie, B. R., McRae, K. B., Gehl, D. and Fillmore, S. A. E. 2015. Pratt timothy. Can. J. Plant Sci. 95: 1047–1048. Pratt timothy (Phleum pratense L.) is an 11-clone synthetic cultivar developed through progeny testing for general combining ability at Agriculture and Agri-Food Canada, Crops and Livestock Research Centre, Charlottetown, Prince Edward Island. Pratt timothy was selected for winter hardiness, plant vigour, plant height, and intermediate maturity (similar to the check cultivar Climax but later than Champ). In Atlantic Canada, Pratt timothy produced more forage than Champ during 3 production years. This cultivar was superior in persistence and re-growth potential with greater production of second-cut herbage.

Sorghum Accessions for Use as Cover Crops and Biofuel Feedstocks

Phenotypes of sorghum species (Sorghum sp.) have characteristics making them valuable summer annual cover crops and/or biofuel feedstocks for temperate climates. In field studies conducted at Urbana, IL, USA, fourteen USDA sorghum landrace accessions and three commercial sorghum accessions were evaluated for their growth habits and regrowth potential. In Canonical Discriminant Analysis (CDA) analysis, the first two canonical variates were significant and accounted for 86% of the among-accession variability. Unmown tiller number, regrowth tiller number, and regrowth biomass best discriminated between accessions in CDA and scattergrams. The accessions clustered into three subgroups. Three multi-stemmed accessions (two commercial varieties and one USDA accession) with an ability to regrow clustered away from the bulk of the USDA sorghums. Multi-stemmed accessions are useful for breeding improved summer annual cover crops that are tall, produce copious amounts of biomass, and rapidly regrow after defoliation; although propensity to lodging and poor germination of accessions will need attention. Additionally, landrace sorghum accessions in the USDA germplasm collection are useful for breeding cover crop and biofuel feedstocks, due to their great height and biomass production, although it will be necessary to select for improved regrowth potential. Crosses between USDA landraces and the commercially available multi-stemmed accessions could lead to a sorghum cover crop and biofuel plant with great biomass and height and ability to regrow following defoliation.

Inactivation and regrowth of multidrug resistant bacteria in urban wastewater after disinfection by solar-driven and chlorination processes

Solar disinfection and solar-driven advanced oxidation processes (AOPs) (namely H2O2/sunlight, TiO2/sunlight, H2O2/TiO2/sunlight, solar photo-Fenton) were evaluated in the inactivation of indigenous antibiotic-resistant bacteria (ARB) in real urban wastewater. A multidrug resistant (MDR) Escherichia coli strain isolated from the effluent of the biological process of an urban wastewater treatment plant was the target ARB. The higher inactivation rates (residual density under detection limit, 2CFUmL−1) were achieved with H2O2/TiO2/sunlight (cumulative energy per unit of volume (QUV) in the range 3–5kJL−1, depending on H2O2/TiO2 ratio) and H2O2/sunlight (QUV of 8kJL−1) processes. All investigated processes did not affect antibiotic resistance of survived colonies. Moreover, H2O2/sunlight was compared with conventional chlorination process to evaluate bacterial regrowth potential and particularly the proportion of indigenous MDR E. coli with respect to total indigenous E. coli population. Chlorination (1.0mg Cl2L−1) was more effective than H2O2/sunlight (50mg H2O2L−1) to achieve total inactivation of MDR E. coli (15min Vs 90min) but less effective in controlling their regrowth (24h Vs 48h). Interestingly, the percentage of MDR E. coli in H2O2/sunlight treated samples decreased as incubation time increased; the opposite was observed for chlorinated samples.

Aminocyclopyrachlor Absorption and Translocation in Three Aquatic Weeds

Studies were conducted to evaluate 14C-aminocyclopyrachlor absorption and translocation in alligatorweed, waterhyacinth, and waterlettuce. Alligatorweed plants were treated at the seven-node stage, waterhyacinth was treated at the five-leaf stage, and waterlettuce was treated at the eight-leaf stage. All plants were pretreated with nonlabeled aminocyclopyrachlor at 0.14 kg ai ha−1 with 1% (v/v) methylated seed oil (MSO). 14C-aminocyclopyrachlor was then applied to a protected leaf, and plants were harvested at 1, 2, 4, 12, 24, and 96 h after treatment (HAT). Radioactivity was determined in the treated leaf, shoots above treated leaf, shoots below treated leaf, roots, and growing solution. Absorption was rapid in all species and reached a maximum of 73, 72, and 73% of applied radioactivity for alligatorweed, waterhyacinth, and waterlettuce, respectively. In alligatorweed at 96 HAT, 43% of absorbed carbon-14 (14C) was translocated to shoots above the treated leaf and 17% was translocated to lower shoot tissue. In waterhyacinth at 96 HAT, 56% of absorbed 14C remained in the treated leaf, whereas 14 and 13% were found in parts above and below the treated leaf, respectively. In waterlettuce at 96 HAT, 50 and 33% of absorbed radioactivity was located above the treated leaf and in the growing solution, respectively. The low recovery of aminocyclopyrachlor in alligatorweed roots and growing solution might explain regrowth potential after herbicide treatment. These results also indicate that the lack of waterlettuce control with aminocyclopyrachlor is not due to reduced absorption or translocation.

Assessment of biological activated carbon treatment to control membrane fouling in reverse osmosis of secondary effluent for reuse in irrigation

Biologically treated secondary effluent (BTSE) is being used increasingly as a source of water for irrigation purposes. Biological activated carbon (BAC) was investigated as a pre-treatment to reduce the organic fouling and biofouling potential of reverse osmosis (RO) membranes for the desalination of a moderately saline BTSE to be used for agricultural purposes. The BAC reduced the organic content through biodegradation by the microorganisms and adsorption by the activated carbon, and subsequent microfiltration (0.1μm PVDF) further reduced the organic content and thus fouling of the RO membrane. The BAC treatment was shown to effectively reduce the biodegradable dissolved organic carbon and assimilable organic carbon contents, and the bacterial regrowth potential, thus confirming its potential for mitigating biofouling of the RO membrane. The improved RO performance demonstrated that this process was effective for reducing the fouling propensity of the BTSE to enable its sustainable application for producing an effluent with a high reuse potential for irrigation purposes. The RO permeate can then be blended with untreated water to produce a product with a suitable inorganic content for irrigation.

Temperature-dependent change of light dose effects on E. coli inactivation during simulated solar treatment of secondary effluent

In this study, simulation of solar disinfection of secondary effluents was performed, to assess the dose effects, as instructed by the reciprocity law. A full factorial experimental design on the operational parameters of the process was performed (time, temperature, bacterial load, light intensity) and three response variables were estimated (disinfection efficiency, regrowth after 24, and 48h). In the 240 disinfection experiments, an erratic behavior was observed in all responses to light exposure, attributed to the combination of both irradiation intensity and temperature during treatment. As a result, the validity of the reciprocity law between light dose and irradiation intensity is challenged. The majority of the cases failed to comply with it, indicating the dependence on temperature conditions, as well as the applied intensity. Dose affected the bacterial regrowth potential after 24 and 48h in a more conventional way. It appears that in order to attain a valid projection of the outcome of solar disinfection in secondary effluent, intensity and dose are not the only parameters to be considered, with temperature also having to be taken under consideration.

Abstract 339: Inhibition of NANOG/NANOGP8 downregulates MCL-1 in colorectal cancer (CRC) cells, enhances the efficacy of BH3 mimetics and inhibits clonogenicity

Abstract Combining lentiviral (LV) delivered shRNA against NANOG (shNG-1) or NANOGP8 (shNp8-1) with BH3 mimetics (ABT-737 and ABT-199) was undertaken to determine whether inhibition of NANOG/NANOGP8 enhances the cytotoxic effect of these BH3 mimetics in Colorectal Cancer (CRC) cells. NANOG is a key transcription factor important for both pluripotency in embryonic stem cells and malignant transformation and progression of colorectal carcinoma (CRC). Inhibition of NANOG or its paralog NANOGP8 reduces the proliferation, stemness and tumorigenicity of CRC cells. The cytotoxic potential of ABT-737 or ABT-199, as single agents, was tested in the CRC cell lines- Clone A, CX-1 and LS174T that have high levels of anti-apoptotic BCL-2 family proteins. Treatment with ABT-737 or ABT-199 showed variable cytotoxicity in the three CRC lines with LS174T being the most resistant. Inhibition of NANOG and NANOGP8 with LVshNG-1 or LVshNp8-1 in these cell lines decreased expression of MCL-1. The combination of LVshNG-1 and/or LVshNp8-1, with ABT-737 produced enhanced killing of the CRC cells by caspase-dependent apoptosis. These results were were confirmed when LV shNG-1 or LV shNp8-1 was used in combination with ABT-199. siRNA targeting MCL-1 reproduced the effects of NANOG/NANOGP8 inhibition. The CRC cells that survived the combination treatment showed lower regrowth potential and reduced clonogenicity when re-plated in fresh media. These results demonstrate that inhibition of NANOGP8 or NANOG enhances the cytotoxicity of BH3 mimetics that target BCL-2 family members through inhibition of MCL-1 expression. Citation Format: Abid R. Mattoo, Jingyu Zhang, Luis A. Espinoza, Snorri S. Thorgeirsson, J. M. Jessup. Inhibition of NANOG/NANOGP8 downregulates MCL-1 in colorectal cancer (CRC) cells, enhances the efficacy of BH3 mimetics and inhibits clonogenicity. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 339. doi:10.1158/1538-7445.AM2014-339

Regrowth Potential of Bacteria after Ultraviolet Disinfection in the Absence of Light and Dark Repair

The objective of this study was to investigate the regrowth potential of E. coli and indigenous wastewater bacteria after ultraviolet (UV) disinfection in the absence of light and dark repair and under different nutrient conditions. Light repair was prevented by keeping the samples in the dark following UV exposure (15 and 40 mJ/cm2). Dark repair was controlled for by varying the initial and surviving bacterial concentrations, and achieving complete inactivation and no growth in control samples. Net growth and die-off in samples were determined 6, 18, 24, 30, and 48 h after UV disinfection. The results of this study showed that the percent regrowth of E. coli and indigenous wastewater bacteria were higher after UV disinfection at 40 mJ/cm2 than at 15 mJ/cm2, and the regrowth was also sustained for a longer time. Even in the absence of any nutrients, significant regrowth of E. coli was observed in phosphate-buffered saline (PBS) indicating that the lysis of UV-damaged cells may provide a source of nutrients for the surviving bacteria. In spite of the availability of nutrients in wastewater, the presence of inhibiting and toxic substances appeared to slow down the regrowth of E. coli. Indigenous coliform bacteria in wastewater could achieve much higher regrowth compared to laboratory cultured E. coli even after a UV dose of 40 mJ/cm2.

Using coagulation to restrict microbial re-growth in tap water by phosphate limitation in water treatment

Extensive microbial re-growth in a drinking water distribution system can deteriorate water quality. The limiting factor for microbial re-growth in a tap water produced by a conventional drinking water treatment plant in China was identified by determining the microbial re-growth potential (MRP) by adding different nutrients to stimulate growth of a natural microbial consortium as inoculum and flow-cytometric enumeration. No obvious change of MRP was found in tap water after addition of carbon, whereas, a 1- to 2-fold increase of MRP was observed after addition of phosphate (P). This clearly demonstrated that microbial re-growth in this tap water was limited by P. Most of the re-grown microbial flora (>85%) consisted of high nucleic acid content cells.A subsequent investigation of the MRP in the actual water treatment plant demonstrated that coagulation was the crucial step for decreasing MRP and producing P-limited water. Therefore, a comparison concerning the control of MRP by three different coagulants was conducted. It showed that all the three coagulants efficiently reduced the MRP and shifted the limitation regime from C to P, but the required dose was different. The study shows that it is feasible to restrict microbial re-growth by P limitation using coagulation in water treatment.

Assessing microbiological water quality in drinking water distribution systems with disinfectant residual using flow cytometry

Flow cytometry (FCM) as a diagnostic tool for enumeration and characterization of microorganisms is rapidly gaining popularity and is increasingly applied in the water industry. In this study we applied the method to obtain a better understanding of total and intact cell concentrations in three different drinking water distribution systems (one using chlorine and two using chloramines as secondary disinfectants). Chloramine tended to result in lower proportions of intact cells than chlorine over a wider residual range, in agreement with existing knowledge that chloramine suppresses regrowth more efficiently. For chlorinated systems, free chlorine concentrations above 0.5 mg L−1 were found to be associated with relatively low proportions of intact cells, whereas lower disinfectant levels could result in substantially higher percentages of intact cells. The threshold for chlorinated systems is in good agreement with guidelines from the World Health Organization. The fact that the vast majority of samples failing the regulatory coliform standard also showed elevated proportions of intact cells suggests that this parameter might be useful for evaluating risk of failure. Another interesting parameter for judging the microbiological status of water, the biological regrowth potential, greatly varied among different finished waters providing potential help for investment decisions. For its measurement, a simple method was introduced that can easily be performed by water utilities with FCM capability.

Laser nanosurgery of cerebellar axons in vivo.

Only a few neuronal populations in the central nervous system (CNS) of adult mammals show local regrowth upon dissection of their axon. In order to understand the mechanism that promotes neuronal regeneration, an in-depth analysis of the neuronal types that can remodel after injury is needed. Several studies showed that damaged climbing fibers are capable of regrowing also in adult animals. The investigation of the time-lapse dynamics of degeneration and regeneration of these axons within their complex environment can be performed by time-lapse two-photon fluorescence (TPF) imaging in vivo. This technique is here combined with laser surgery, which proved to be a highly selective tool to disrupt fluorescent structures in the intact mouse cortex. This protocol describes how to perform TPF time-lapse imaging and laser nanosurgery of single axonal branches in the cerebellum in vivo. Olivocerebellar neurons are labeled by anterograde tracing with a dextran-conjugated dye and then monitored by TPF imaging through a cranial window. The terminal portion of their axons are then dissected by irradiation with a Ti:Sapphire laser at high power. The degeneration and potential regrowth of the damaged neuron are monitored by TPF in vivo imaging during the days following the injury.

Laser Nanosurgery of Cerebellar Axons <em>In Vivo</em>

Only a few neuronal populations in the central nervous system (CNS) of adult mammals show local regrowth upon dissection of their axon. In order to understand the mechanism that promotes neuronal regeneration, an in-depth analysis of the neuronal types that can remodel after injury is needed. Several studies showed that damaged climbing fibers are capable of regrowing also in adult animals1,2. The investigation of the time-lapse dynamics of degeneration and regeneration of these axons within their complex environment can be performed by time-lapse two-photon fluorescence (TPF) imaging in vivo3,4. This technique is here combined with laser surgery, which proved to be a highly selective tool to disrupt fluorescent structures in the intact mouse cortex5-9. This protocol describes how to perform TPF time-lapse imaging and laser nanosurgery of single axonal branches in the cerebellum in vivo. Olivocerebellar neurons are labeled by anterograde tracing with a dextran-conjugated dye and then monitored by TPF imaging through a cranial window. The terminal portion of their axons are then dissected by irradiation with a Ti:Sapphire laser at high power. The degeneration and potential regrowth of the damaged neuron are monitored by TPF in vivo imaging during the days following the injury.

Stomatal Development and Associated Photosynthetic Characteristics of Watermelon (Citrullus lanatus) Plug Seedlings during Light Storage

Illumination during storage was proven to extend the storability of seedlings, but little attention has been given to the underlying mechanism. To determine how light conditions affect photosynthetic status in watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] plug seedlings, differences of stomatal development and relative photosynthetic characteristics of expanding new leaves when stored for 8 days at 15 °C in light at a photosynthetic photon flux (PPF) of 15 μmol·m−2·s−1 or darkness were investigated. The stomatal density (SD) increased with time to a peak and then decreased from the start of storage in light to the subsequent transplantation. Dark storage retarded the stomatal development and delayed the appearance of the peak of SD. Compared with those under dark storage, light-stored seedlings showed significantly higher SD and stomatal index (SI) in leaves accompanied by higher maximal photochemical efficiency of PSII (Fv/Fm) and quantum yield of PSII (ΦPSII). During storage in darkness, Fv/Fm and ΦPSII declined steeply with increasing storage duration but recovered gradually to reach the same level of those in light at the fourth day after transplanting. Seedlings stored in light for 8 days showed higher net photosynthesis rate (Pn), stomatal conductance (gS), intercellular CO2 concentration (Ci), and transpiration rate (Tr) than in darkness. The post-storage recovery of Pn, gS, and Tr were closely related to the SI, which ensured the fast recovery of photosynthesis during the early stage of transplanting. In agreement with the change of SD, no differences in Pn, gS, Ci, and Tr between light and dark storage were observed after 8 days of transplantation. Seedlings stored in light appeared vigorous and the shoot dry weight was significantly higher than that of dark-stored ones. Although seedlings in dark storage had a poor appearance during storage, they showed inhibited regrowth potentials during the subsequent transplanting stage. This study exhibited that light in short-term storage contributed to maintaining stomatal development as well as photosynthetic efficiency in watermelon, which could also extend to post-storage for ensuring the transplant quality of seedlings after removal from storage.

Changes in water biostability levels in water treatment trials.

This article presents the results of studies of changes in water biostability levels in water treatment systems. In order to evaluate the potential of microorganism regrowth, both the organic and non-organic nutrient substrate content was taken into account. Pre-treatment in the analyzed water treatment plants ensured high phosphate ion removal effectiveness but a significantly worse effectiveness in removing biodegradable dissolved organic carbon (BDOC). Lowering nutrient substrate content during the main treatment stage was only possible in water treatment systems that incorporated biological processes. Conversely, final water treatment processes only influenced BDOC content in the treated water. Irrespective of the water type and unit treatment process, the limiting factors for microorganism regrowth in the distribution system were the phosphate ion content and BDOC content. However, none of the analyzed treatment systems ensured a reduction in non-organic nitrogen content that would ensure biological stability of the water.

The Use of Multiple Tracers to Evaluate the Impact of Sewered and Non‐Sewered Development on Coastal Water Quality in a Rural Area of Florida

When onsite wastewater treatment and disposal systems (OSTDS) are not sited appropriately or installed properly, wastewater constituents can be a source of adverse environmental impacts to soil and groundwater, which can lead to potential public health risks. A paired monitoring design developed to compare water quality in sewered and non-sewered areas is presented here. It is suggested as a possible monitoring scheme for assessing the impact of sewer installation projects. As such, two sets of single-family, rural residential Florida neighborhoods were evaluated over a two-year period to gain insight into the effects of small-community use of OSTDS on coastal water quality. One set of two neighborhoods were connected to the sanitary sewer network and the other set of two were served exclusively by OSTDS. Water quality sampling was conducted at the paired sites during seasonal high water table (SHWT) and seasonal low water table (SLWT) events. Measured surface water quality during the SHWT showed indications of environmental impacts from OSTDS in terms of nutrients, microbial pathogen indicators, and other water quality measures, such as turbidity and conductivity. However, during the SLWT events, no obvious impacts attributable to OSTDS were detected. The water quality results indicate that OSTDS impacts may be measureable in rural areas. Other factors, such as microbial indicator survival and regrowth potential, may confound the understanding of water quality impacts of sewer projects. For example, the microbial indicators Escherichia coli and enterococci were found to persist over time and therefore did not always represent true comparisons of OSTDS and sewered areas between seasons. The timeframe for evaluating the effects of sewer projects may be longer than anticipated because of this survival and regrowth phenomenon.

Methods to Analyze Bone Regenerative Response to Different rhBMP-2 Doses in Rabbit Craniofacial Defects

Multiple assessment methods are available to evaluate the performance of engineered scaffolds in accepted bone healing animal models. Evaluation and comparison of these methods can aid in the planning of future animal studies, as well as, inform clinical assessments as the engineered scaffolds translate into clinical studies and applications. To evaluate multiple bone assessment techniques, bone regrowth potential of tyrosine-derived polycarbonate (TyrPC) scaffolds loaded with various dosages of recombinant human bone morphogenetic protein-2 (rhBMP-2) (0, 10, 25, and 50 μg) was assessed after 16 weeks in vivo in a rabbit calvarial model. Traditional X-ray radiography and micro-computed tomography (micro-CT) analyses were used to quantify the volume and density of regenerated bone. Histomorphometric analysis was performed as the traditional gold standard of evaluation. While these techniques are fairly standard in bone tissue engineering, we also investigated 64-slice CT, a tool more commonly used clinically, for comparison and to guide translational efforts. The 64-slice CT scans were carried out at 4 and 16 weeks to monitor temporal bone healing patterns. Study results indicated a clear dose-dependent response of increasing regenerated bone volume with rhBMP-2 loaded on the TyrPC scaffolds after 16 weeks of implantation. Significantly more bone formation was observed at the highest dose of rhBMP-2 (50 μg), which is 25-50% of the previously recommended dose (100-200 μg) for this defect. A significant difference was observed between the lowest and highest doses using radiographs (p<0.001), micro-CT (p=0.002), and CT (p<0.001) and a high correlation was found between techniques (R(2) values between 0.446 and 0.911). It was found that the number of animals required per group to detect significant dose effects ranged between 6 and 8 for the imaging methods while histomorphometric analysis would require 25 animals per group to detect similar differences (desired power=0.9, α=0.05). Radiographic analysis provided quantifiable % defect coverage and radio-opacity, micro-CT provided spatial volumetric and bone density measures, histomorphometry provided biological confirmation, and 64-slice CT allowed for establishing of clinically relevant translational guidelines. These methodologies allow for a standardized and comprehensive description of bone regeneration and provide guidelines for the planning of future preclinical and clinical studies.