Late Health Effects of Partial Body Irradiation Injury in a Minipig Model Are Associated with Changes in Systemic and Cardiac IGF-1 Signaling.

Clinical, epidemiological, and experimental evidence demonstrate non-cancer, cardiovascular, and endocrine effects of ionizing radiation exposure including growth hormone deficiency, obesity, metabolic syndrome, diabetes, and hyperinsulinemia. Insulin-like growth factor-1 (IGF-1) signaling perturbations are implicated in development of cardiovascular disease and metabolic syndrome. The minipig is an emerging model for studying radiation effects given its high analogy to human anatomy and physiology. Here we use a minipig model to study late health effects of radiation by exposing male Göttingen minipigs to 1.9-2.0 Gy X-rays (lower limb tibias spared). Animals were monitored for 120 days following irradiation and blood counts, body weight, heart rate, clinical chemistry parameters, and circulating biomarkers were assessed longitudinally. Collagen deposition, histolopathology, IGF-1 signaling, and mRNA sequencing were evaluated in tissues. Our findings indicate a single exposure induced histopathological changes, attenuated circulating IGF-1, and disrupted cardiac IGF-1 signaling. Electrolytes, lipid profiles, liver and kidney markers, and heart rate and rhythm were also affected. In the heart, collagen deposition was significantly increased and transforming growth factor beta-1 (TGF-beta-1) was induced following irradiation; collagen deposition and fibrosis were also observed in the kidney of irradiated animals. Our findings show Göttingen minipigs are a suitable large animal model to study long-term effects of radiation exposure and radiation-induced inhibition of IGF-1 signaling may play a role in development of late organ injuries.

Circadian rhythms driving a fast-paced root clock implicate species-specific regulation in Medicago truncatula.

Plants have a hierarchical circadian structure comprising multiple tissue-specific oscillators that operate at different speeds and regulate the expression of distinct sets of genes in different organs. However, the identity of the genes differentially regulated by the circadian clock in different organs, such as roots, and how their oscillations create functional specialization remain unclear. Here, we profiled the diurnal and circadian landscapes of the shoots and roots of Medicago truncatula and identified the conserved regulatory sequences contributing to transcriptome oscillations in each organ. We found that the light-dark cycles strongly affect the global transcriptome oscillation in roots, and many clock genes oscillate only in shoots. Moreover, many key genes involved in nitrogen fixation are regulated by circadian rhythms. Surprisingly, the root clock runs faster than the shoot clock, which is contrary to the hierarchical circadian structure showing a slow-paced root clock in both detached and intact Arabidopsis thaliana (L.) Heynh. roots. Our result provides important clues about the species-specific circadian regulatory mechanism, which is often overlooked, and possibly coordinates the timing between shoots and roots independent of the current prevailing model.

Sebaceous lipids are essential for water repulsion, protection against UVB-induced apoptosis and ocular integrity in mice.

Sebocytes, which are characterized by lipid accumulation that leads to cell disruption, can be found in hair follicle-associated sebaceous glands (SGs) or in free SGs such as the Meibomian glands in the eyelids. Because genetic tools that allow targeting of sebocytes while maintaining intact epidermal lipids are lacking, the relevance of sebaceous lipids in health and disease remains poorly understood. Using Scd3, which is expressed exclusively in mature sebocytes, we established a mouse line with sebocyte-specific expression of Cre recombinase. Both RT-PCR analysis and crossing into Rosa26-lacZ reporter mice and Kras(G12D) mice confirmed Cre activity specifically in SGs, with no activity in other skin compartments. Importantly, loss of SCD3 function did not cause detectable phenotypical alterations, endorsing the usefulness of Scd3-Cre mice for further functional studies. Scd3-Cre-induced, diphtheria chain A toxin-mediated depletion of sebaceous lipids resulted in impaired water repulsion and thermoregulation, increased rates of UVB-induced epidermal apoptosis and caused a severe pathology of the ocular surface resembling Meibomian gland dysfunction. This novel mouse line will be useful for further investigating the roles of sebaceous lipids in skin and eye integrity.

Regional signals in the planarian body guide stem cell fate in the presence of genomic instability.

Cellular fate decisions are influenced by their topographical location in the adult body. For instance, tissue repair and neoplastic growth are greater in anterior than in posterior regions of adult animals. However, the molecular underpinnings of these regional differences are unknown. We identified a regional switch in the adult planarian body upon systemic disruption of homologous recombination with RNA-interference of Rad51 Rad51 knockdown increases DNA double-strand breaks (DSBs) throughout the body, but stem cells react differently depending on their location along the anteroposterior axis. In the presence of extensive DSBs, cells in the anterior part of the body resist death, whereas cells in the posterior region undergo apoptosis. Furthermore, we found that proliferation of cells with DNA damage is induced in the presence of brain tissue and that the retinoblastoma pathway enables overproliferation of cells with DSBs while attending to the demands of tissue growth and repair. Our results implicate both autonomous and non-autonomous mechanisms as key mediators of regional cell behavior and cellular transformation in the adult body.

Is there a measure for low power laser dose?

Low power lasers have been used successfully for treatment of many diseases in soft and bone tissues. Basic and clinical researches have developed quickly being the scientific basis to therapeutic protocols based on these lasers. However, there are difficulties to compare experimental and clinical results obtained from different researchers because a complicated and intricate list of physical and biological parameters should be checked before the irradiation procedures as well as part of these parameters are omitted or inaccurately reported. This review focuses on the physical and biological parameters proposed to make experimental and clinical protocols accurate and reproducible as well as suggests dose parameters based on biological effects induced by low power lasers. A variety of parameters are reported by different authors and the number of parameter suggested could overcome three dozens. Thus, laser dose and laser dose equivalent are defined based on laser-induced biological effects and suggested as simplified dose parameters for low power lasers. These parameters could simplify and be useful to researchers and clinicians, permitting comparisons and decreasing mistakes and inaccuracies when laser-induced effects are evaluated and compared with those obtained in previous studies. The laser dose and laser dose equivalent could contribute significantly to improve accuracy, effectiveness, and safety of clinical protocols based on low power lasers.

A uORF Represses the Transcription Factor AtHB1 in Aerial Tissues to Avoid a Deleterious Phenotype.

AtHB1 is an Arabidopsis (Arabidopsis thaliana) homeodomain-leucine zipper transcription factor that participates in hypocotyl elongation under short-day conditions. Here, we show that its expression is posttranscriptionally regulated by an upstream open reading frame (uORF) located in its 5' untranslated region. This uORF encodes a highly conserved peptide (CPuORF) that is present in varied monocot and dicot species. The Arabidopsis uORF and its maize (Zea mays) homolog repressed the translation of the main open reading frame in cis, independent of the sequence of the latter. Published ribosome footprinting results and the analysis of a frame-shifted uORF, in which the repression capability was lost, indicated that the uORF causes ribosome stalling. The regulation exerted by the CPuORF was tissue specific and did not act in the absence of light. Moreover, a photosynthetic signal is needed for the CPuORF action, since plants with uncoupled chloroplasts did not show uORF-dependent repression. Plants transformed with the native AtHB1 promoter driving AtHB1 expression did not show differential phenotypes, whereas those transformed with a construct in which the uORF was mutated exhibited serrated leaves, compact rosettes, and, most significantly, short nondehiscent anthers and siliques containing fewer or no seeds. Thus, we propose that the uncontrolled expression of AtHB1 is deleterious for the plant and, hence, finely repressed by a translational mechanism.

Transient Receptor Potential Vanilloid 4 Ion Channel Functions as a Pruriceptor in Epidermal Keratinocytes to Evoke Histaminergic Itch.

TRPV4 ion channels function in epidermal keratinocytes and in innervating sensory neurons; however, the contribution of the channel in either cell to neurosensory function remains to be elucidated. We recently reported TRPV4 as a critical component of the keratinocyte machinery that responds to ultraviolet B (UVB) and functions critically to convert the keratinocyte into a pain-generator cell after excess UVB exposure. One key mechanism in keratinocytes was increased expression and secretion of endothelin-1, which is also a known pruritogen. Here we address the question of whether TRPV4 in skin keratinocytes functions in itch, as a particular form of "forefront" signaling in non-neural cells. Our results support this novel concept based on attenuated scratching behavior in response to histaminergic (histamine, compound 48/80, endothelin-1), not non-histaminergic (chloroquine) pruritogens in Trpv4 keratinocyte-specific and inducible knock-out mice. We demonstrate that keratinocytes rely on TRPV4 for calcium influx in response to histaminergic pruritogens. TRPV4 activation in keratinocytes evokes phosphorylation of mitogen-activated protein kinase, ERK, for histaminergic pruritogens. This finding is relevant because we observed robust anti-pruritic effects with topical applications of selective inhibitors for TRPV4 and also for MEK, the kinase upstream of ERK, suggesting that calcium influx via TRPV4 in keratinocytes leads to ERK-phosphorylation, which in turn rapidly converts the keratinocyte into an organismal itch-generator cell. In support of this concept we found that scratching behavior, evoked by direct intradermal activation of TRPV4, was critically dependent on TRPV4 expression in keratinocytes. Thus, TRPV4 functions as a pruriceptor-TRP in skin keratinocytes in histaminergic itch, a novel basic concept with translational-medical relevance.

Identification and functional characterization of a p-coumaroyl CoA 2'-hydroxylase involved in the biosynthesis of coumarin skeleton from Peucedanum praeruptorum Dunn.

KEY MESSAGE: A p-coumaroyl CoA 2'-hydroxylase responsible for the formation of coumarin lactone ring was identified from Peucedanum praeruptorum Dunn and functionally characterized in vitro. Coumarins are important plant secondary metabolites with a variety of biological activities. Ortho-hydroxylation of cinnamates leads to the formation of coumarin lactone ring and is generally thought to be a key step in coumarin biosynthesis. However, ortho-hydroxylases, especially p-coumaroyl CoA 2'-hydroxylase (C2'H) responsible for the biosynthesis of the most common coumarin skeleton, have received insufficient attention. Here, a putative ortho-hydroxylase PpC2'H was isolated from P. praeruptorum Dunn, a traditional Chinese medicinal herb rich in coumarins. Expression profile indicated that PpC2'H exhibited the highest transcript level in roots and could be up-regulated by MeJA elicitation. Subcellular localization of PpC2'H was demonstrated to be cytosol in planta. In order to functionally characterize PpC2'H, the purified recombinant protein was incubated with various potential substrates. HPLC-ESI-MS analysis indicated that PpC2'H catalyzed the conversion of p-coumaroyl CoA into hydroxylated intermediate, which then underwent spontaneous lactonization to generate umbelliferone. Our data also showed that light would promote the spontaneous process. In addition, based on homology modeling and site-directed mutagenesis, amino acid residues Phe-130, Lys-141, Asn-207, His-224, Asp-226, His-282 and Phe-298 were verified essential for enzymatic activity. These findings provide insight into structure-function relationship of this pivotal ortho-hydroxylase and also contribute to elucidating the biosynthetic mechanism of coumarin skeleton.

Autofluorescence spectroscopy for nerve-sparing laser surgery of the head and neck-the influence of laser-tissue interaction.

The use of remote optical feedback systems represents a promising approach for minimally invasive, nerve-sparing laser surgery. Autofluorescence properties can be exploited for a fast, robust identification of nervous tissue. With regard to the crucial step towards clinical application, the impact of laser ablation on optical properties in the vicinity of structures of the head and neck has not been investigated up to now. We acquired 24,298 autofluorescence spectra from 135 tissue samples (nine ex vivo tissue types from 15 bisected pig heads) both before and after ER:YAG laser ablation. Sensitivities, specificities, and area under curve(AUC) values for each tissue pair as well as the confusion matrix were statistically calculated for pre-ablation and post-ablation autofluorescence spectra using principal component analysis (PCA), quadratic discriminant analysis (QDA), and receiver operating characteristics (ROC). The confusion matrix indicated a highly successful tissue discrimination rate before laser exposure, with an average classification error of 5.2%. The clinically relevant tissue pairs nerve/cancellous bone and nerve/salivary gland yielded an AUC of 100% each. After laser ablation, tissue discrimination was feasible with an average classification accuracy of 92.1% (average classification error 7.9%). The identification of nerve versus cancellous bone and salivary gland performed very well with an AUC of 100 and 99%, respectively. Nerve-sparing laser surgery in the area of the head and neck by means of an autofluorescence-based feedback system is feasible even after ER-YAG laser-tissue interactions. These results represent a crucial step for the development of a clinically applicable feedback tool for laser surgery interventions in the oral and maxillofacial region.

Contribution of PsbS Function and Stomatal Conductance to Foliar Temperature in Higher Plants.

Natural capacity has evolved in higher plants to absorb and harness excessive light energy. In basic models, the majority of absorbed photon energy is radiated back as fluorescence and heat. For years the proton sensor protein PsbS was considered to play a critical role in non-photochemical quenching (NPQ) of light absorbed by PSII antennae and in its dissipation as heat. However, the significance of PsbS in regulating heat emission from a whole leaf has never been verified before by direct measurement of foliar temperature under changing light intensity. To test its validity, we here investigated the foliar temperature changes on increasing and decreasing light intensity conditions (foliar temperature dynamics) using a high resolution thermal camera and a powerful adjustable light-emitting diode (LED) light source. First, we showed that light-dependent foliar temperature dynamics is correlated with Chl content in leaves of various plant species. Secondly, we compared the foliar temperature dynamics in Arabidopsis thaliana wild type, the PsbS null mutant npq4-1 and a PsbS-overexpressing transgenic line under different transpiration conditions with or without a photosynthesis inhibitor. We found no direct correlations between the NPQ level and the foliar temperature dynamics. Rather, differences in foliar temperature dynamics are primarily affected by stomatal aperture, and rapid foliar temperature increase during irradiation depends on the water status of the leaf. We conclude that PsbS is not directly involved in regulation of foliar temperature dynamics during excessive light energy episodes.

Organ specificity in the plant circadian system is explained by different light inputs to the shoot and root clocks.

Circadian clocks allow the temporal compartmentalization of biological processes. In Arabidopsis, circadian rhythms display organ specificity but the underlying molecular causes have not been identified. We investigated the mechanisms responsible for the similarities and differences between the clocks of mature shoots and roots in constant conditions and in light : dark cycles. We developed an imaging system to monitor clock gene expression in shoots and light- or dark-grown roots, modified a recent mathematical model of the Arabidopsis clock and used this to simulate our new data. We showed that the shoot and root circadian clocks have different rhythmic properties (period and amplitude) and respond differently to light quality. The root clock was entrained by direct exposure to low-intensity light, even in antiphase to the illumination of shoots. Differences between the clocks were more pronounced in conditions where light was present than in constant darkness, and persisted in the presence of sucrose. We simulated the data successfully by modifying those parameters of a clock model that are related to light inputs. We conclude that differences and similarities between the shoot and root clocks can largely be explained by organ-specific light inputs. This provides mechanistic insight into the developing field of organ-specific clocks.

Characterization of photomorphogenic responses and signaling cascades controlled by phytochrome-A expressed in different tissues.

The photoreceptor phytochrome A acts as a light-dependent molecular switch and regulates responses initiated by very low fluences of light (VLFR) and high fluences (HIR) of far-red light. PhyA is expressed ubiquitously, but how phyA signaling is orchestrated to regulate photomorphogenesis is poorly understood. To address this issue, we generated transgenic Arabidopsis thaliana phyA-201 mutant lines expressing the biologically active phyA-YFP photoreceptor in different tissues, and analyzed the expression of several reporter genes, including ProHY5:HY5-GFP and Pro35S:CFP-PIF1, and various FR-HIR-dependent physiological responses. We show that phyA action in one tissue is critical and sufficient to regulate flowering time and root growth; control of cotyledon and hypocotyl growth requires simultaneous phyA activity in different tissues; and changes detected in the expression of reporters are not restricted to phyA-containing cells. We conclude that FR-HIR-controlled morphogenesis in Arabidopsis is mediated partly by tissue-specific and partly by intercellular signaling initiated by phyA. Intercellular signaling is critical for many FR-HIR induced responses, yet it appears that phyA modulates the abundance and activity of key regulatory transcription factors in a tissue-autonomous fashion.

Investigation of relative metabolic changes in the organs and plasma of rats exposed to X-ray radiation using HR-MAS (1)H NMR and solution (1)H NMR.

Excess exposure to ionizing radiation generates reactive oxygen species and increases the cellular inflammatory response by modifying various metabolic pathways. However, an investigation of metabolic perturbations and organ-specific responses based on the amount of radiation during the acute phase has not been conducted. In this study, high-resolution magic-angle-spinning (HR-MAS) NMR and solution NMR-based metabolic profiling were used to investigate dose-dependent metabolic changes in multiple organs and tissues--including the jejunum, spleen, liver, and plasma--of rats exposed to X-ray radiation. The organs, tissues, and blood samples were obtained 24, 48, and 72 h after exposure to low-dose (2 Gy) and high-dose (6 Gy) X-ray radiation and subjected to metabolite profiling and multivariate analyses. The results showed the time course of the metabolic responses, and many significant changes were detected in the high-dose compared with the low-dose group. Metabolites with antioxidant properties showed acute responses in the jejunum and spleen after radiation exposure. The levels of metabolites related to lipid and protein metabolism were decreased in the jejunum. In addition, amino acid levels increased consistently at all post-irradiation time points as a consequence of activated protein breakdown. Consistent with these changes, plasma levels of tricarboxylic acid cycle intermediate metabolites decreased. The liver did not appear to undergo remarkable metabolic changes after radiation exposure. These results may provide insight into the major metabolic perturbations and mechanisms of the biological systems in response to pathophysiological damage caused by X-ray radiation.

Shade-induced stem elongation in rice seedlings: Implication of tissue-specific phytohormone regulation.

A better understanding of shade avoidance syndrome (SAS) is an urgent need because of its effect on energy reallocation. Leverage-related mechanism in crops is of potential economic interest for agricultural applications. Here we report the SAS phenotype at tissue level rice seedlings. Tissue-specific RNA-sequencing indicates auxin plays different roles between coleoptile and the first leaf. Phenotypes of wild type treated by gibberellin and brassinosteroid biosynthesis inhibitors and of related mutants suggest these two hormones positively regulate SAS. Our work reveals the diversity of hormone responses in different organs and different species in shade conditions.

Calculations of S values and effective dose for the radioiodine carrier and surrounding individuals based on Chinese hybrid reference phantoms using the Monte Carlo technique.

The S values for the thyroid as the radioiodine source organ to other target organs were investigated using Chinese hybrid reference phantoms and the Monte Carlo code MCNP5. Two radioiodine isotopes (125)I and (131)I uniformly distributed in the thyroid were investigated separately. We compared our S values for (131)I in Chinese phantoms with previous studies using other types of phantoms: Oak Ridge National Laboratory (ORNL) stylized phantoms, International Commission on Radiological Protection (ICRP) voxel phantoms, and University of Florida (UF) phantoms. Our results are much closer to the UF phantoms. For each specific target organ, the S value for (131)I is larger than for (125)I in both male and female phantoms. In addition, the S values and effective dose to surrounding face-to-face exposed individuals, including different genders and ages (10- and 15-year-old juniors, and adults) from an adult male radioiodine carrier were also investigated. The target organ S values and effective dose for surrounding individuals obey the inverse square law with the distance between source and target phantoms. The obtained effective dose data in Chinese phantoms are comparable to the results in a previous study using the UF phantoms. The data generated in this study can serve as the reference to make recommendations for radiation protection of the Chinese patients or nuclear workers.

Behavior of bone marrow-derived cells following in vivo transplantation: differentiation into stromal cells with roles in organ maintenance.

After injection of green fluorescent protein-positive (GFP(+)) bone marrow (BM) cells into lethally irradiated wild-type mice, the organs of the recipient mice [BM transplantation (BMT) mice] were regenerated; however, irradiation of the cecum or spleen (only) blocked their regeneration with loss of injected BM cells. These results suggest that the donor cells first enter the BM and then migrate to the peripheral organs. The maintenance of epithelial structure and function is controlled by interactions between stromal cells and the epithelia; the organ is stable only if the stroma is functioning normally. In BMT mice, intestinal GFP(+) stromal cells were regenerated fairly rapidly although GFP(+) cells were observed only rarely in the intestinal epithelium even if it passes several weeks or months post BMT, indicating that BM-derived stromal cells play a pivotal role in epithelial renewal and are crucial for maintaining organ structure and function. BM-derived cells in the periphery possess a special key to return to the BM and then to migrate to various organs to become resident cells.

Tissue-specific and light-dependent regulation of phytochrome gene expression in rice.

Phytochromes are red- and far red light photoreceptors in higher plants. Rice (Oryza sativa L.) has three phytochromes (phyA, phyB and phyC), which play distinct as well as cooperative roles in light perception. To gain a better understanding of individual phytochrome functions in rice, expression patterns of three phytochrome genes were characterized using promoter-GUS fusion constructs. The phytochrome genes PHYA and PHYB showed distinct patterns of tissue- and developmental stage-specific expression in rice. The PHYA promoter-GUS was expressed in all leaf tissues in etiolated seedlings, while its expression was restricted to vascular bundles in expanded leaves of light-grown seedlings. These observations suggest that light represses the expression of the PHYA gene in all cells except vascular bundle cells in rice seedlings. Red light was effective, but far red light was ineffective in gene repression, and red light-induced repression was not observed in phyB mutants. These results indicate that phyB is involved in light-dependent and tissue-specific repression of the PHYA gene in rice.

Three-dimensional patterns of cell division and expansion throughout the development of Arabidopsis thaliana leaves.

Variations in size and shape of multicellular organs depend on spatio-temporal regulation of cell division and expansion. Here, cell division and expansion rates were quantified relative to the three spatial axes in the first leaf pair of Arabidopsis thaliana. The results show striking differences in expansion rates: the expansion rate in the petiole is higher than in the leaf blade; expansion rates in the lateral direction are higher than longitudinal rates between 5 and 10 days after stratification, but become equal at later stages of leaf blade development; and anticlinal expansion co-occurs with, but is an order of magnitude slower than periclinal expansion. Anticlinal expansion rates also differed greatly between tissues: the highest rates occurred in the spongy mesophyll and the lowest in the epidermis. Cell division rates were higher and continued for longer in the epidermis compared with the palisade mesophyll, causing a larger increase of palisade than epidermal cell area over the course of leaf development. The cellular dynamics underlying the effect of shading on petiole length and leaf thickness were then investigated. Low light reduced leaf expansion rates, which was partly compensated by increased duration of the growth phase. Inversely, shading enhanced expansion rates in the petiole, so that the blade to petiole ratio was reduced by 50%. Low light reduced leaf thickness by inhibiting anticlinal cell expansion rates. This effect on cell expansion was preceded by an effect on cell division, leading to one less layer of palisade cells. The two effects could be uncoupled by shifting plants to contrasting light conditions immediately after germination. This extended kinematic analysis maps the spatial and temporal heterogeneity of cell division and expansion, providing a framework for further research to understand the molecular regulatory mechanisms involved.

A novel mitochondrial DnaJ/Hsp40 family protein BIL2 promotes plant growth and resistance against environmental stress in brassinosteroid signaling.

Plant steroid hormones, brassinosteroids, are essential for growth, development and responses to environmental stresses in plants. Although BR signaling proteins are localized in many organelles, i.e., the plasma membrane, nuclei, endoplasmic reticulum and vacuole, the details regarding the BR signaling pathway from perception at the cellular membrane receptor BRASSINOSTEROID INSENSITIVE 1 (BRI1) to nuclear events include several steps. Brz (Brz220) is a specific inhibitor of BR biosynthesis. In this study, we used Brz-mediated chemical genetics to identify Brz-insensitive-long hypocotyls 2-1D (bil2-1D). The BIL2 gene encodes a mitochondrial-localized DnaJ/Heat shock protein 40 (DnaJ/Hsp40) family, which is involved in protein folding. BIL2-overexpression plants (BIL2-OX) showed cell elongation under Brz treatment, increasing the growth of plant inflorescence and roots, the regulation of BR-responsive gene expression and suppression against the dwarfed BRI1-deficient mutant. BIL2-OX also showed resistance against the mitochondrial ATPase inhibitor oligomycin and higher levels of exogenous ATP compared with wild-type plants. BIL2 participates in resistance against salinity stress and strong light stress. Our results indicate that BIL2 induces cell elongation during BR signaling through the promotion of ATP synthesis in mitochondria.

The effects of a stimulating intron on the expression of heterologous genes in Arabidopsis thaliana.

Introns are often added to transgenes to increase expression, although the mechanism through which introns stimulate gene expression in plants and other eukaryotes remains mysterious. While introns vary in their effect on expression, it is unknown whether different genes respond similarly to the same stimulatory intron. Furthermore, the degree to which gene regulation is preserved when expression is increased by an intron has not been thoroughly investigated. To test the effects of the same intron on the expression of a range of genes, GUS translational fusions were constructed using the promoters of eight Arabidopsis genes whose expression was reported to be constitutive (GAE1, CNGC2 and ROP10), tissue specific (ADL1A, YAB3 and AtAMT2) or regulated by light (ULI3 and MSBP1). For each gene, a fusion containing the first intron from the UBQ10 gene was compared to fusions containing the gene's endogenous first intron (if the gene has one) or no intron. In every case, the UBQ10 intron increased expression relative to the intronless control, although the magnitude of the change and the level of expression varied. The UBQ10 intron also changed the expression patterns of the CNGC2 and YAB3 fusions to include strong activity in roots, indicating that tissue specificity was disrupted by this intron. In contrast, the regulation of the ULI3 and MSBP1 genes by light was preserved when their expression was stimulated by the intron. These findings have important implications for biotechnology applications in which a high level of transgene expression in only certain tissues is desired.