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1.
A phenological study is one of the first steps in understanding the function of ecosystems. This is because phenological events reflect the way in which the species exploit the so‐called favourable periods in order to gain carbon and to allocate photosynthetic products for growth and reproduction. The objective of the present work was to examine the phenology of reproduction and the above‐ground growth of several Cenchrus ciliaris accessions, growing under the arid bioclimate in Tunisia. These accessions collected in the south of Tunisia are: Bou Hedma (P1), Tozeur (P2), Raas Jedir (P3) and Sidi Toui (P4). It was demonstrated that an important phenological variability exists within the different accessions studied. The statistical analysis (correlation and principal component analysis) showed that the accession from Bou Hedma (P1) was the most precocious and vigorous one. 相似文献
2.
Amina Kharrat‐Souissi Alex Baumel Khalil Mseddi Franck Torre Mohamed Chaieb 《African Journal of Ecology》2011,49(2):209-220
This study deals with the phenotypic polymorphism of twenty accessions of Cenchrus ciliaris L. (buffelgrass) collected in various climatic areas of Tunisia. Six seedlings per accession were cultivated according to a common garden experiment design, and 33 phenological or morphological variables were measured during one cycle of growth. The observed differences among accessions were not significant for the seedling stage, but they were significant for all other studied variables of the vegetative and reproductive growth, dry matter and habit type. The principal component analysis provided further support for the important fixed genetic polymorphism of this species. On the other hand, a hierarchical classification was used to classify accessions in four groups, but we did not observe a clear geographical pattern associated with these groups. In conclusion, our study revealed considerable genotypic variation for C. ciliaris across Tunisia, which could be preserved by the agamospermous system of reproduction. Finally, among the groups from hierarchical classification, Mezzouna‐08 accession may be a good choice for the restoration of degraded Tunisian ecosystems, thanks to its high aboveground biomass productivity. 相似文献
3.
Introduced grasses have displaced Hawaiian Pili grass (Heteropogon contortus) in most dry, leeward habitats of the Hawaiian Islands. The purpose of this study was to assess the feasibility of restoring an indigenous Heteropogon grassland at the Puukohola Heiau National Historic Site, where introduced Buffel grass (Cenchrus ciliaris) is now dominant. Heteropogon seeds (50 seedlings/m2) were added to replicate plots within a Cenchrus grassland. Some plots were subjected to one‐time herbicide or hand‐pulling treatments to remove established Cenchrus. Because Hawaiians historically used fire to promote Heteropogon grasslands, the plots were burned biennially. Plots were also subjected to two levels of water supplementation. Heteropogon establishment was monitored over 2 and 4 years in the higher‐ and lower‐water plots, respectively. In treatments containing established Cenchrus, Heteropogon establishment was consistently poor (<10% cover). But in the burned plots where established Cenchrus had been removed, as many as 31 Heteropogon seedlings per square meter were recorded, and Heteropogon became the dominant cover, averaging 34% absolute cover (81% relative cover) after 4 years in the lower‐water plot and 34% absolute cover (60% relative cover) after 2 years in the higher‐water plot. Few Cenchrus grass seedlings survived, possibly due to insufficient water. Water supplementation promoted growth of other alien grasses from the seed bank (Digitaria insularis and Eragrostis spp.); however, these grasses quickly declined after supplemental watering was terminated. Although initial suppression of Cenchrus was required, Heteropogon expanded quickly when seeds and fire were reintroduced, demonstrating that a Heteropogon‐dominated grassland can be reestablished in 2–4 years. 相似文献
4.
Despite high deforestation rates in dry forests there are few assessments of the impacts of this transformation on biodiversity. This study addresses the impact of clearing on plant species composition and diversity in mulga (Acacia aneura) forests of Queensland, Australia using data collected from either side of 58 clearing boundaries, incorporating data on site and management conditions. The physical and climatic conditions of the study sites were narrowly constrained but had greater influence on plant composition and richness than clearing per se. In general, the abundance of perennial forbs and shrubs was higher in cleared forest compared with adjacent intact forest and there was no significant difference in abundance of other plant life forms. Perennial forb richness diminished with the age of clearings, particularly where acid sub‐soils had been exposed and shrubs proliferated. Where deforestation in the mulga dry forests is not accompanied by the establishment of exotic pasture it has a relatively benign effect on plant diversity, mulga itself remains in high density as small trees and the integrity of the forest could be maintained with restoration. 相似文献
5.
Reduced leaf size is often correlated to increased aridity, where smaller leaves demand less water via xylem conduits. However, it is unknown if differences in three-dimensional (3D) xylem connectivity reflect leaf-level adaptations. We used X-ray microtomography (micro-CT) to quantify 3D xylem connectivity in ～5 mm diameter branch sections of co-occurring semi-arid Acacia species of varied phyllode size. We compared 3D connectivity to minimum branch water potential and two-dimensional (2D) vessel attributes derived from sections produced by micro-CT. 2D attributes included vessel area, density, vessel size to number ratio (S) and vessel lumen fraction (F). Trees with terete phyllodes had less negative water potentials than broad phyllode variants. 3D xylem connectivity was conserved across all trees regardless of phyllode type or minimum water potential. We also found that xylem connectivity was sensitive to vessel lumen fraction (F) and not the size to number ratio (S) even though F was consistent among species and phyllode variants. Our results demonstrate that differences in phyllode anatomy, and not xylem connectivity, likely explain diversity of drought tolerance among closely related Acacia species. Further analysis using our approach across a broader range of species will improve understanding of adaptations in the xylem networks of arid zone species. 相似文献
6.
利用原状土连续就地取样(sequentialcoringandin-situexposure)方法研究了澜沧江流域典型退化土壤的氮库营养动态变化过程,监测了矿质氮在时间和空间上的释放与固定、淋失与植物吸收消耗。结果表明人为干扰影响土壤氮矿质化,导致氮固定、淋失,引起养分衰减退化。从阔叶林转变为果园、坡耕地、桉树林和针叶林,矿质氮60d内平均衰减分别为51.51,29.64,26.84,16.40mg·kg-1,变异程度依次为21.5%、11.0%、14.2%、8.3%,氮固定分别为15.45,8.51,13.90,0.00mg·kg-1,淋失量则坡耕地最大,达44.50mg·kg-1,其次是针叶林和桉树林地,分别为38.41和25.30mg·kg-1。植物对土壤氮的吸收消耗为果园>坡耕地作物>桉树林>针叶林>阔叶林,利用形态以硝态氮为主。 相似文献
7.
The aim of the study was to determine tolerance of plant growth promoting rhizobacteria (PGPR) in different concentrations of Cu, Cr, Co, Cd, Ni, Mn, and Pb and to evaluate the PGPR-modulated bioavailability of different heavy metals in the rhizosphere soil and wheat tissues, grown in saline sodic soil. Bacillus cereus and Pseudomonas moraviensis were isolated from Cenchrus ciliaris L. growing in the Khewra salt range. Seven-day-old cultures of PGPR were applied on wheat as single inoculum, co-inoculation and carrier-based biofertilizer (using maize straw and sugarcane husk as carrier). At 100 ppm of Cr and Cu, the survival rates of rhizobacteria were decreased by 40%. Single inoculation of PGPR decreased 50% of Co, Ni, Cr and Mn concentrations in the rhizosphere soil. Co-inoculation of PGPR and biofertilizer treatment further augmented the decreases by 15% in Co, Ni, Cr and Mn over single inoculation except Pb and Co where decreases were 40% and 77%, respectively. The maximum decrease in biological concentration factor (BCF) was observed for Cd, Co, Cr, and Mn. P. moraviensis inoculation decreases the biological accumulation coefficient (BAC) as well as translocation factor (TF) for Cd, Cr, Cu Mn, and Ni. The PGPR inoculation minimized the deleterious effects of heavy metals, and the addition of carriers further assisted the PGPR. 相似文献
8.
The aim of the study was to map the distribution of Acacia senegal and its infraspecific taxa in Uganda and predict its suitable range of occurrence based on climatic factors. The distribution of the infraspecific taxa was analysed for richness, diversity, turnover and reserve selection. Regression analysis was performed to understand the relationship between distribution of the species and climatic variables. Georeferenced species occurrence points were superimposed over temperature and vapour maps. Areas with highest taxa richness, diversity and turnover were mapped and found in the Lake Kyoga basin. The species shows preference for the northern region of the study area with dissimilar climatic pattern from the southern region and the superimposition supported findings. Variety kerensis exhibited narrower climatic, altitudinal and distribution range preference. Temperature seasonality, maximum temperature of warmest month, temperature annual range, mean temperatures of warmest and driest quarters had the highest coefficients of determination (r2 > 0.7) hence most important in influencing species distribution. The most appropriate locations for in situ conservation and for germplasm collection to ensure maximum diversity is secured are found in Wabisi‐Wajala, Kiula, Kyalubanga, Bajo, Kasagala, Kabwika‐mujwalanganda, Maruzi, Moroto and Napak Central Forest Reserves. The study recommends ecological studies to understand status of A. senegal. 相似文献
9.
Gabrielle Lebbink John Matthew Dwyer Rod John Fensham 《Ecological Management & Restoration》2021,22(1):5-9
Protecting native biodiversity is a difficult prospect in extremely modified landscapes, especially where high‐impact exotic species are widespread. Using new data and a review of the literature, this paper comments on the use of livestock grazing to manage the invasive and highly combustible pasture grass species, Buffel Grass (Cenchrus ciliaris) and thereby help conserve fire‐sensitive Brigalow (Acacia harpophylla) vegetation in reserves in Queensland, Australia. We cite evidence that shows that grazing is a potentially useful management tool in such cases and its use can be compatible with the protection of both fire‐sensitive vegetation and other native plant species within the understorey. However, there are limitations in implementing grazing within conservation reserves including the lack of a clear understanding of the influence of grazing on biodiversity and resource condition. Importantly, we highlight secondary invasion by the exotic grass Indian Couch (Bothriochloa pertusa) as a key emerging threat that may undermine the biodiversity benefits gained by grazing in reserves. Grazing can be a useful tool for conservation management in particular scenarios, but the associated risks demand accompanying monitoring and reporting of positive and negative impacts to ensure the fundamental aim of biodiversity protection is being achieved. 相似文献
10.
Alejandro E. Castellanos Hernn Celaya‐Michel Julio C. Rodríguez Bradford P. Wilcox 《Ecohydrology》2016,9(8):1663-1674
In arid and semiarid lands worldwide, vegetation cover is being transformed to savannas dominated by exotic grasses. However, the ecohydrological and biogeochemical changes associated with this process remain little understood. For more than 3 years, we studied soil moisture dynamics in natural semiarid shrubland patches and compared those with changes in an adjacent site that had been transformed to an exotic buffelgrass (Cenchrus ciliaris) savanna. We found that volumetric soil moisture was higher in patches with some kind of cover. For both tree and bare patches, volumetric soil moisture and plant‐available water in the 60‐ to 100‐cm depth interval were significantly lower in the savanna than in the natural site. In buffelgrass patches, volumetric soil moisture and plant‐available water were higher at almost all depths and in wet years and increased significantly during the summer monsoon season, suggesting rapid infiltration mechanisms under buffelgrass. During years with wet winters, these mechanisms also led to brief accumulations of water in the soil profile (0–200 cm). Such changes in soil profile water dynamics brought about adaptive responses in perennial plant species. The ability of species to change their patterns of soil water use in the profile may be an important mechanism enabling them to compete when novel tree–grass interactions are established by invasion of grasses. Our results provide new insights for understanding the changes caused by grass invasion in arid and semiarid lands, as well as how these changes may impact ecohydrological dynamics in global change scenarios. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
11.
Brett P. Murphy Paolo Paron Lynda D. Prior Guy S. Boggs Donald C. Franklin David M. J. S. Bowman 《Journal of Biogeography》2010,37(11):2169-2182
Aim To develop a new modelling approach for spatially autocorrelated non‐normal data, and apply it to a case study of the role that fire–vegetation–soil feedbacks play in maintaining boundaries between fire‐sensitive and fire‐promoted plant communities. Location A mulga (Acacia aneura) shrubland–spinifex (Triodia spp.) grassland mosaic, central Australia. Methods Autoregressive error models were extended to non‐normal data by incorporating neighbourhood values of the response and predictor variables into generalized nonlinear models. These models were used to examine the environmental correlates of three response variables: mulga cover; fire frequency in areas free of mulga; and the presence of mulga banding. Mulga cover and mulga banding were assessed visually by overlaying 4477 × 1 km2 grid cells on both Landsat 7 ETM+ and very high resolution imagery. Fire frequency was estimated from an existing fire history for central Australia, based on remotely sensed fire scars. Results The autoregressive error models explained 27%, 47% and 57% of the null deviance of mulga cover, fire frequency and mulga banding, respectively, with 12%, 15% and 24% of the null deviance being explained by environmental variables alone. These models accounted for virtually all residual spatial autocorrelation. While there was a clear negative relationship between mulga cover and fire frequency, there was little evidence that mulga was being restricted to parts of the landscape with inherently low fire frequencies. Mulga was most abundant at very low slope angles and on red earths, both of which are likely to reflect high site productivity, while fire frequency was not clearly affected by slope angle and was also relatively high on red earths. Main conclusions The modelling approach we have developed provides a much needed way of analysing spatially autocorrelated non‐normal data and can be easily incorporated into an information‐theoretic modelling framework. Using this approach, we provide evidence that mulga and spinifex have a highly antagonistic relationship. In more productive parts of the landscape, mulga suppresses spinifex and fire, while in less productive parts of the landscape, fire and spinifex suppress mulga, leading to the remarkable abruptness of mulga–spinifex boundaries that are maintained via fire–vegetation–soil feedbacks. 相似文献
12.
硝化抑制剂DCD、 DMPP对褐土氮总矿化速率和硝化速率的影响 总被引：5，自引：0，他引：5
采用15N库稀释-原位培养法研究了硝化抑制剂DCD、DMPP对华北盐碱性褐土氮总矿化速率和硝化速率的影响.试验在山西省运城市种植玉米的盐碱性土壤上进行,设单施尿素、尿素+DCD、尿素+DMPP 3个处理.结果表明:施肥后2周,DCD、DMPP分别使氮总矿化速率和氮总硝化速率减少了25.5％、7.3％和60.3％、59.1％,DCD对氮总矿化速率的影响显著高于DMPP,两者对氮总硝化速率的影响无显著差异;而在施肥后7周,不同硝化抑制剂对氮总硝化速率的影响存在差异.施肥后2周,3个处理的土壤氮总矿化速率和硝化速率分别是施肥前的7.2 ～10.0倍和5.5 ～21.5倍;NH4+和NO3-消耗速率分别是施肥前的9.1 ～12.2倍和5.1 ～8.4倍,这是由氮肥对土壤的激发效应所致.硝化抑制剂使氮肥更多地以NH4+形式保持在土壤中,减少了NO3-的积累.土壤氮总矿化速率和总硝化速率受硝化抑制剂的抑制是N2O减排的主要原因. 相似文献
13.
Simulating the effects of N availability, straw particle size and location in soil on C and N mineralization 总被引：2，自引：0，他引：2
Predicting the C and N mineralization of straw added to soil is important for forecasting subsequent soil N availability during
and between crop growth cycles. The decomposition module of the STICS model, parameterized under optimal conditions, was used
to predict straw decomposition in sub-optimal conditions, i.e. when contact between soil and residue was poor (due to large
size residues or surface placement) or when mineral N availability was restricted. The data used in the simulations were obtained
from published studies of effects of residue size, location and N availability on C and N mineralization from straw under
controlled laboratory conditions. We selected studies in which the dynamics of C and N mineralization were measured simultaneously.
The dynamics of straw mineralization could be well predicted by the model under optimal conditions with standard parameter
values as derived from measured C/N ratios of the residues, but not under sub-optimal conditions which required a new parameterization. A good fit could be obtained
on these treatments by a marked reduction in the rate constants of residue and microbial biomass decomposition and a marked
increase in the microbial biomass C/N ratio. Our results show the need to include in decomposition models routines for simulating effects of spatial heterogeneity
of residue distribution, different particle sizes and limiting N availability. 相似文献
14.
Aaryn D. Olsson Julio Betancourt Mitchel P. McClaran Stuart E. Marsh 《Diversity & distributions》2012,18(1):10-21
Aim Biological invasions facilitate ecosystem transformation by altering the structure and function, diversity, dominance and disturbance regimes. A classic case is the grass–fire cycle in which grass invasion increases the frequency, scale and/or intensity of wildfires and promotes the continued invasion of invasive grasses. Despite wide acceptance of the grass–fire cycle, questions linger about the relative roles that interspecific plant competition and fire play in ecosystem transformations. Location Sonoran Desert Arizona Upland of the Santa Catalina Mountains, Arizona, USA. Methods We measured species cover, density and saguaro (Carnegiea gigantea) size structure along gradients of Pennisetum ciliare invasion at 10 unburned/ungrazed P. ciliare patches. Regression models quantified differences in diversity, cover and density with respect to P. ciliare cover, and residence time and a Fisher’s exact test detected demographic changes in saguaro populations. Because P. ciliare may have initially invaded locations that were both more invasible and less diverse, we ran analyses with and without the plots in which initial infestations were located. Results Richness and diversity decreased with P. ciliare cover as did cover and density of most dominant species. Richness and diversity declined with increasing time since invasion, suggesting an ongoing transformation. The proportion of old‐to‐young Carnegiea gigantea was significantly lower in plots with dominant P. ciliare cover. Main conclusions Rich desert scrub (15–25 species per plot) was transformed into depauperate grassland (2–5 species per plot) within 20 years following P. ciliare invasion without changes to the fire regime. While the onset of a grass–fire cycle may drive ecosystem change in the later stages and larger scales of grass invasions of arid lands, competition by P. ciliare can drive small‐scale transformations earlier in the invasion. Linking competition‐induced transformation rates with spatially explicit models of spread may be necessary for predicting landscape‐level impacts on ecosystem processes in advance of a grass–fire cycle. 相似文献
15.
16.
Abstract. Questions: This paper examines the long‐term change in the herbaceous layer of semi‐arid vegetation since grazing ceased. We asked whether (1) there were differences in the temporal trends of abundance among growth forms of plants; (2) season of rainfall affected the growth form response; (3) the presence of an invasive species influenced the abundance and species richness of native plants relative to non‐invaded plots, and (4) abundance of native plants and/or species richness was related to the time it took for an invasive species to invade a plot. Location: Alice Springs, Central Australia. Methods: Long‐term changes in the semi‐arid vegetation of Central Australia were measured over 28 years (1976–2004) to partition the effects of rainfall and an invasive perennial grass. The relative abundance (biomass) of all species was assessed 25 times in each of 24 plots (8 m × 1 m) across two sites that traversed floodplains and adjacent foot slopes. Photo‐points, starting in 1972, were also used to provide a broader overview of a landscape that had been intensively grazed by cattle and rabbits prior to the 1970s. Species’abundance data were amalgamated into growth forms to examine their relationship with environmental variation in space and time. Environmental variables included season and amount of rainfall, fire history, soil variability and the colonization of the plots by the exotic perennial grass Cenchrus ciliaris (Buffel grass). Results: Constrained ordination showed that season of rainfall and landscape variables relating to soil depth strongly influenced vegetation composition when Cenchrus was used as a covariate. When Cenchrus was included in constrained ordination, it was strongly related to the decline of all native growth forms over time. Univariate comparisons of non‐invaded vs impacted plots over time revealed unequivocal evidence that Cenchrus had caused the decline of all native growth form groups and species richness. They also revealed a contrasting response of native plants to season of rainfall, with a strong response of native grasses to summer rainfall and forbs to winter rainfall. In the presence of Cenchrus these responses were strongly attenuated. Discussion: Pronounced changes in the composition of vegetation were interpreted as a response to removal of grazing pressure, fluctuations in rainfall and, most importantly, invasion of an exotic grass. Declines in herbaceous species abundance and richness in the presence of Cenchrus appear to be directly related to competition for resources. Indirect effects may also be causing the declines of some woody species from changed fire regimes as a result of increased fuel loads. We predict that Cenchrus will begin to alter landscape level processes as a result of the direct and indirect effects of Cenchrus on the demography of native plants when there is a switch from resource limited (rainfall) establishment of native plants to seed limited recruitment. 相似文献
17.
Under the harsh environmental conditions present in severely overgrazed, semiarid rangelands, facilitator plants offer a promising tool for ecological restoration. This study investigated facilitative effects of Aloe secundiflora—a native drought‐tolerant, unpalatable, thorny shrub—on grass establishment in degraded rangelands in Kenya. We planted native perennial grass seeds adjacent to three neighbor treatments: transplanted mature aloe shrubs, piles of thorn branches that provided similar physical protection to aloes, and control treatments with no facilitator. We monitored grass performance for three growing seasons. During the first growing season, association with aloe shrubs significantly improved seedling survival and plant size of individual grasses, whereas grass survival in thorn treatments was intermediate between aloe and control treatments. At the population level, aloe neighbor treatments were associated with the greatest grass abundance and cover in all three seasons and reproductive output in the second season. Control treatments were associated with the poorest grass performance for all three variables. The findings indicate that planting aloes can improve the effectiveness of grass reseeding for rangeland restoration, exceeding the benefits gained from the more common strategy of using thorn branch piles. The utility of aloes in particular is further enhanced by the economic value of these plants; medicinal sap can be sustainably harvested from aloes planted for restoration. 相似文献
18.
Microbial dynamics and carbon and nitrogen cycling following re-wetting of soils beneath two semi-arid plant species 总被引：17，自引：0，他引：17
Sporadic summer rainfall in semi-arid ecosystems can provide enough soil moisture to drastically increase CO2 efflux and rates of soil N cycling. The magnitudes of C and N pulses are highly variable, however, and the factors regulating these pulses are poorly understood. We examined changes in soil respiration, bacterial, fungal and microfaunal populations, and gross rates of N mineralization, nitrification, and NH4+ and NO3– immobilization during the 10 days following wetting of dry soils collected from stands of big sagebrush (Artemisia tridentata) and cheatgrass (Bromus tectorum) in central Utah. Soil CO2 production increased more than tenfold during the 17 h immediately following wetting. The labile organic C pool released by wetting was almost completely respired within 2–3 days, and was nearly three times as large in sagebrush soil as in cheatgrass. In spite of larger labile C pools beneath sagebrush, microbial and microfaunal populations were nearly equal in the two soils. Bacterial and fungal growth coincided with depletion of labile C, and populations peaked in both soils 2 days after wetting. Protozoan populations, whose biomass was nearly 3,000-fold lower than bacteria and fungi, peaked after 2–4 days. Gross N mineralization and nitrification rates were both faster in cheatgrass soil than in sagebrush, and caused greater nitrate accumulation in cheatgrass soil. Grazing of bacteria and fungi by protozoans and nematodes could explain neither temporal trends in N mineralization rates nor differences between soil types. However, a mass balance model indicated that the initial N pulse was associated with degradation of microbial substrates that were rich in N (C:N <8.3), and that microbes had shifted to substrates with lower N contents (C:N =15–25) by day 7 of the incubation. The model also suggested that the labile organic matter in cheatgrass soil had a lower C:N ratio than in sagebrush, and this promoted faster N cycling rates and greater N availability. This study provides evidence that the high N availability often associated with wetting of cheatgrass soils is a result of cheatgrass supplying substrates to microbes that are of high decomposability and N content. 相似文献
19.
I. J. Manguiat G. B. Mascariña J. K. Ladha R. J. Buresh J. Tallada 《Plant and Soil》1994,160(1):131-137
Field experiments were conducted under flooded soil conditions using Maahas clay amended with urea and rice straw-sesbania mixtures during the wet and dry seasons. Parallel laboratory incubation tests were done. The objectives were 1) to determine N mineralization patterns and establish the relationship between mineralization parameters and either N availability or grain yield, and 2) to correlate the results of organic N mineralization studies in the laboratory with data from field experiments. The N mineralization patterns of flooded soils in the laboratory followed a logistic function. In laboratory studies, mineralization potential was positively correlated with extractable soil NH4+-N at the end of the incubation period (cumulative available N). Likewise, mineralization potential calculated from laboratory studies was positively correlated with N uptake and grain yield from field studies. Extractable (NH4++NO3–)-N in the field correlated positively with extractable NH4+-N in the laboratory. The extractable NH4+-N from laboratory incubations at 14 days after transplanting, panicle initiation, and maturity was also highly and positively correlated with grain yield from field experiments. 相似文献
20.
Angela Gullard Jelica Gluhak-Heinrich Silvana Papagerakis Philip Sohn Aaron Unterbrink Shuo Chen Mary MacDougall 《The journal of histochemistry and cytochemistry》2016,64(4):224-236
Matrix extracellular phosphoglycoprotein (MEPE) is an extracellular matrix protein found in dental and skeletal tissues. Although information regarding the role of MEPE in bone and disorders of phosphate metabolism is emerging, the role of MEPE in dental tissues remains unclear. We performed RNA in situ hybridization and immunohistochemistry analyses to delineate the expression pattern of MEPE during embryonic and postnatal development in craniofacial mineralizing tissues. Mepe RNA expression was seen within teeth from cap through root formation in association with odontoblasts and cellular cementoblasts. More intense expression was seen in the alveolar bone within the osteoblasts and osteocytes. MEPE immunohistochemistry showed biphasic dentin staining in incisors and more intense staining in alveolar bone matrix and in forming cartilage. Analysis of Mepe null mouse molars showed overall mineralized tooth volume and density of enamel and dentin comparable with that of wild-type samples. However, Mepe-/- molars exhibited increased thickness of predentin, dentin, and enamel over controls and decreased gene expression of Enam, Bsp, Dmp1, Dspp, and Opn by RT-PCR. In vitro Mepe overexpression in odontoblasts led to significant reductions in Dspp reporter activity. These data suggest MEPE may be instrumental in craniofacial and dental matrix maturation, potentially functioning in the maintenance of non-mineralized matrix. 相似文献