Decidual Zone Research Articles

Expression and function of fatty acid–binding protein 4 during mouse decidualization

Fatty acid-binding protein 4 (Fabp4) is highly expressed in the secondary decidual zone of mouse decidua and deciduoma and stromal cells under in vitro decidualization. Dtprp, a well-known marker of in vitro decidualization, is diminished by small interfering RNA against Fabp4 and FABP4 inhibitor and stimulated through Fabp4 overexpression.

Death effector domain–containing protein (DEDD) is required for uterine decidualization during early pregnancy in mice

During intrauterine life, the mammalian embryo survives via its physical connection to the mother. The uterine decidua, which differentiates from stromal cells after implantation in a process known as decidualization, plays essential roles in supporting embryonic growth before establishment of the placenta. Here we show that female mice lacking death effector domain-containing protein (DEDD) are infertile owing to unsuccessful decidualization. In uteri of Dedd-/- mice, development of the decidual zone and the surrounding edema after embryonic implantation was defective. This was subsequently accompanied by disintegration of implantation site structure, leading to embryonic death before placentation. Polyploidization, a hallmark of mature decidual cells, was attenuated in DEDD-deficient cells during decidualization. Such inefficient decidualization appeared to be caused by decreased Akt levels, since polyploidization was restored in DEDD-deficient decidual cells by overexpression of Akt. In addition, we showed that DEDD associates with and stabilizes cyclin D3, an important element in polyploidization, and that overexpression of cyclin D3 in DEDD-deficient cells improved polyploidization. These results indicate that DEDD is indispensable for the establishment of an adequate uterine environment to support early pregnancy in mice.

Altitudinal Movements of Guizhou Snub-Nosed Monkeys (Rhinopithecus brelichi) in Fanjingshan National Nature Reserve, China: Implications for Conservation Management of a Flagship Species

Primate movements can include a substantial altitudinal component, depending on the complexity of the landscape and the distribution of the inherent vegetation zones. We investigated altitudinal movements of Guizhou snub-nosed monkeys (Rhinopithecus brelichi) at Fanjingshan National Nature Reserve, China. The monkeys ranged at elevations between 1,350 and 1,870 m with an overall mean of 1,660 m. We did not find a significant difference in the mean elevations among seasons or evidence of winter migration to lower elevations. The monkeys exhibited a distinct daily altitudinal movement pattern that coincided with their activities. During the day, the monkeys consistently traveled from lower to higher elevations in the morning (98% of records) and then descended to lower elevations in the afternoon (96%). Hence, the mean elevation of night roosts was significantly lower (1,561 m) than those of feeding sites and day roosts (1,735 and 1,737 m, respectively). We suggest that this daily pattern of R. brelichi may reflect a trade-off between finding food and avoiding predation within the mixed evergreen and deciduous broadleaf vegetation zone at the study site, which may constitute the most important habitat for R. brelichi in the reserve.

Adherens Junction Proteins in the Hamster Uterus: Their Contributions to the Success of Implantation.

The adherens junction (AJ), which is an indispensible intercellular unit in the uterine luminal epithelial lining, is important for maintaining uterine structural integrity, composition of luminal environment, and initiation of implantation by virtue of its properties of cell-cell recognition, adhesion, and establishment of cell polarity and permeability barrier by developing tight junctions. In this study, we investigated the uterine changes of AJ components E-cadherin, beta-catenin and alpha-catenin at their protein and mRNA levels together with the cellular distribution of phospho-beta-catenin and active beta-catenin. Studies were performed in hamsters that show only ovarian progesterone-dependent uterine receptivity and implantation similar to humans. By immunofluorescence, in situ hybridization, immunoprecipitation and immuno blotting, we have demonstrated that uterine epithelial cells expressed three of these AJ proteins and their mRNAs prior to and during the initial phase of implantation. With advancement of the implantation process and loss of the epithelial lining surrounding the implanting blastocyst, three components of AJs were primarily expressed in cells of the secondary decidual zone (SDZ), but not in the primary decidual zone (PDZ). In contrast, we noted strong expression of beta-catenin and alpha-catenin proteins in cell of the PDZ, but not in the SDZ, of mice. We also report that uterine beta-catenin may be involved in mediating the Wnt-signaling pathway in the uterus during implantation and decidualization. Taken together, these results demonstrate that uterine AJ junctional proteins are important for cell-cell adhesion and signaling in continuation of pregnancy to ensure protection of the embryo by creating a favorable uterine environment. Research supported by NIH HD044741. (poster)

Effect of Preimplantation Bisphenol-A Exposure on Uterine Receptivity in Mice.

Uterine receptivity is a transient state in which the uterus can accept an embryo to implant into the uterine wall. It is controlled by the ovarian hormones progesterone (P4) and estrogen (E2). P4 and E2 exert their uterine effects mainly through their respective receptors, PR and ER. Bisphenol-A (BPA) is an endocrine disruptor that has been widely used in polycarbonate plastics and epoxy resins. It has been demonstrated that BPA has adverse effects on uterine development and can alter uterine expression of PR and ER. In addition, it has been reported that BPA treatment at ~400 mg/kg/day in early pregnancy is detrimental to embryo implantation. However, it is unknown whether the adverse effect is on the embryo or the uterus or both during embryo implantation. To investigate the potential effect of BPA on uterine receptivity, wild type C57B6/129 mixed background young adult females (4-6 each group) were mated with untreated wild type stud males. The timed pregnant mice were treated with 0, 40, 100, and 400 mg/kg/day BPA (dissolved in sesame oil) daily via subcutaneously injection from embryonic day 0.5 to 3.5. Implantation sites were visualized with Evans blue dye injection at day 4.5 (mating night as day 0, implantation normally initiates ~ day 4.0 in mice). No implantation sites were detected in both100 and 400 mg/kg/day BPA treated groups. No embryos were flushed from these uteri either, indicating that BPA at these high doses are toxic to the early stage embryos. Reduced number of implantation sites were detected in the 40 mg/kg/day BPA treated group. However, the appearance of the blue bands (implantation sites) was not as sharp as those seen in the uteri of the control group. Immunohistochemistry of PR indicated that there was no decidual zone at the implantation sites in the 40 mg/kg/day BPA treated group, and PR was highly expressed in the luminal epithelium, suggesting that implantation was abnormal in this group. PR expression disappeared from the luminal epithelium but was strong in the primary decidal zone in the implantation sites from the control group. PR expression in day 4.5 uteri from both100 and 400 mg/kg/day BPA treated groups was also dysregulated. To further define the effect of BPA on uterine receptivity at these high doses, we will transfer embryos from untreated females into BPA-treated pseudo-pregnant uterus. Our results demonstrate that high doses of BPA are detrimental to early stage embryos and their effect on uterine receptivity awaits further clarification. (Supported by startup funding from The University of Georgia and funding from the Interdisciplinary Toxicology Program at The University of Georgia). (poster)

Drought Tolerance Of <i>Garcinia kola</i> And <i>Garcinia afzelii</i> At The Seedlings Stage

Garcinia kola and Garcinia afzelii are very useful forest tree species for chew stick and medicinal purposes in West Africa. They are currently receiving attention for cultivation due to the dwindling stocks of the species in the natural forest. Soil moisture is one of the most critical environmental factors that affect seedling growth in the field. The study was therefore conducted to test the response of the two species to variability in water availability. The seedlings were subjected to simulated no drought, 15-day drought, 30-day drought and 84-day drought. Seedling response to watering after 60-day simulated drought by withholding of watering was also monitored. Relative growth rate (RGR) in diameter decreased with the prolongation of the simulated drought period, and the difference was significant among all the treatments. For G. afzelii , simulated 84-day drought exhibited negative RGR in diameter, whereas for G. kola both the simulated 30-day and 84-day drought exhibited negative RGR in diameter. The RGR in height and leaf production was similar for the simulated no drought and the 15-day drought but significantly different from the 30-day and the 84-day drought period for G. afzelii. However for G. kola , it was the 15-day and 30-day simulated drought that were similar. Leaf production was highly correlated with height growth than with diameter growth. Release of drought-stress by the resumption of watering triggered leaf shedding up to a minimum value and thereafter increased. The relative rate of leaf production after re-watering increased, however the rate declined with the passage of time for G. afzelii but continued to increase for G. kola. Diameter growth was more affected than height by the dry conditions. The growth performance of G. afzelii was generally better than that of G. kola and both species have mechanisms for overcoming dry periods without experiencing mortality. Garcinia afzelii can be established in any of the forest zones, whereas Garcinia kola should preferably be established in Wet/Moist Forest and moist semi deciduous forest zones. Keywords : Garcinia species, simulated drought, diameter growth, height growth, leaf production

Altered Spatiotemporal Expression of Collagen Types I, III, IV, and VI in Lpar3-Deficient Peri-Implantation Mouse Uterus

Lpar3 is upregulated in the preimplantation uterus, and deletion of Lpar3 leads to delayed uterine receptivity in mice. Microarray analysis revealed that there was higher expression of Col3a1 and Col6a3 in the Preimplantation Day 3.5 Lpar3(-/-) uterus compared to Day 3.5 wild-type (WT) uterus. Since extracellular matrix (ECM) remodeling is indispensable during embryo implantation, and dynamic spatiotemporal alteration of specific collagen types is part of this process, this study aimed to characterize the expression of four main uterine collagen types: fibril-forming collagen (COL) I and COL III, basement membrane COL IV, and microfibrillar COL VI in the peri-implantation WT and Lpar3(-/-) uterus. An observed delay of COL III and COL VI clearance in the Lpar3(-/-) uterus may be associated with higher preimplantation expression of Col3a1 and Col6a3. There was also delayed clearance of COL I and delayed deposition of COL IV in the decidual zone in the Lpar3(-/-) uterus. These changes were different from the effects of 17beta-estradiol and progesterone on uterine collagen expression in ovariectomized WT uterus, indicating that the altered collagen expression in Lpar3(-/-) uterus is unlikely to be a result of alterations in ovarian hormones. Decreased expression of several genes encoding matrix-degrading metallo- and serine proteinases was observed in the Lpar3(-/-) uterus. These results demonstrate that pathways downstream of LPA3 are involved in the dynamic remodeling of ECM in the peri-implantation uterus.

Extracellular matrix remodelling in rat endometrium during early pregnancy: The role of fibronectin and laminin

The endometrial extracellular matrix (ECM) remodelling has a crucial role in the establishment of a successful pregnancy. In addition to its basic function such as regulation of cell function, differentiation, migration, proliferation, the substantial alterations in the endometrial ECM may play a specific role in the trophoblast invasion, placentation, cell death and formation of the proper and functional implantation chamber around the embryo. In the present study, immunolocalizations of fibronectin and laminin were determined using avidin–biotin complex–peroxidase in rat implantation sites during 7–10 days of pregnancy. Both proteins were present in the basal membrane of blood vessels and in decidual matrix whereas they were absent or had very weak reactivity in the primary decidual zone on day 7. When placentation has begun, the immunoreactivity of both proteins was increased in the placental bed and in the basal membrane of blood vessels of the mesometrial region. The immunolocalization of both proteins seemed to be decreased in the antimesometrial decidua, however, it was increased in the mesometrial decidual matrix on days 9 and 10. Therefore, it could be suggested laminin and fibronectin demonstrating dynamic expressions in relation with the morphological differentiation of endometrial stroma may play crucial roles in the control of trophoblast adhesion and invasion, in placentation and angiogenesis, in the determination of cell shape and fate thus contributing the endometrial receptivity and a successful pregnancy.

Role of secretory protease inhibitor SPINK3 in mouse uterus during early pregnancy

Successful embryo implantation depends on intricate epithelial-stromal cross-talk. However, molecular modulators involved in this cellular communication remain poorly elucidated. Using multiple approaches, we have investigated the spatiotemporal expression and regulation of serine protease inhibitor Kazal type 3 (SPINK3) in mouse uterus during the estrous cycle and early pregnancy. In cycling mice, both SPINK3 mRNA and protein are only expressed during proestrus. In the pregnant mouse, the expression levels of both SPINK3 mRNA and protein increase on days 5-8 and then decline. Spink3 mRNA is expressed exclusively in the uterine glandular epithelium, whereas SPINK3 protein is localized on the surface of both luminal and glandular epithelium and in the decidua. Moreover, SPINK3 in the decidua has been observed in the primary decidual zone on day 6 and the secondary decidual zone on days 7-8; this is tightly associated with the progression of decidualization. SPINK3 has also been found in decidual cells of the artificially decidualized uterine horn but not control horn, whereas Spink3 mRNA localizes in the glands of both horns. The expression of endometrial Spink3 is not regulated by the blastocyst according to its expression pattern during pseudopregnancy and delayed implantation but is induced by progesterone and further augmented by a combination of progesterone and estrogen in ovariectomized mice. Thus, uterine-gland-derived SPINK3, as a new paracrine modulator, might play an important role in embryo implantation through its influence on stromal decidualization in mice.

Glis glis (Rodentia: Gliridae)

Glis glis (Linnaeus, 1766) is a glirid commonly called the fat or edible dormouse. It is the largest dormouse and the only species in the genus Glis. Range mainly overlaps with a deciduous and mixed forest zone in Europe and southwestern Asia. Principal habitat is deciduous and mixed woodland and the species is strictly nocturnal. G. glis is unusual among small rodents in its long life expectancy (mean is about 9 years), prolonged hibernation (up to 7 months), and periodic reproductive failure. It is a species of conservation concern along the northern part of its range, and a game animal in Slovenia and Croatia.

Distribution and status of medicinal leeches (genus Hirudo) in the Western Palaearctic: anthropogenic, ecological, or historical effects?

Abstract1. Distribution and status of medicinal leeches were re‐considered in the light of the new taxonomy recognizing four Western Palaearctic species: Hirudo medicinalis, Hirudo verbana, Hirudo orientalis and Hirudo troctina.2. Recent records and new data obtained on expeditions to Ukraine, Russia, Azerbaijan, Kazakhstan, Uzbekistan and the Western Balkans were mapped to obtain an up‐to‐date overview of the distribution.3. Three hypotheses explaining the current ranges of all Hirudo species were tested. The ecological hypothesis, suggesting a strong impact of large‐scale environmental factors, received the highest support, while anthropogenic influence was minimal, and no historical patterns of refugia and colonization were detected.4. Mapped localities of all Hirudo species show extensive, belt‐shaped ranges extending from east to west. H. medicinalis is distributed from Britain and southern Norway to the southern Urals and probably as far as the Altai Mountains, occupying the deciduous arboreal zone. H. verbana has been recorded from Switzerland and Italy to Turkey and Uzbekistan, which largely corresponds to the Mediterranean and sub‐boreal steppe zone. H. orientalis is associated with mountainous areas in the sub‐boreal eremial zone and occurs in Transcaucasian countries, Iran and Central Asia. H. troctina has been found in north‐western Africa and Spain in the Mediterranean zone.5. Based on the data gathered, and considering real and potential threats, global IUCN category Near Threatened is proposed for H. medicinalis, H. verbana, and H. orientalis, while H. troctina can only be assigned to category Data Deficient. Copyright © 2010 John Wiley & Sons, Ltd.

Updated estimate of carbon balance on Russian territory

The land use system in Russia changed considerably after 1990: 30.2 million ha of croplands were abandoned. Based on the own field investigations that were carried out in abandoned lands of different age (Luvic Phaeozems, deciduous forest zone; Moscow region, 54.50N, 37.37E), it has been shown that after 4.5 yr of abandonment, the former croplands acted as a stable sink of CO2. The net ecosystem production (NEP) in the post-agrogenic ecosystems averaged 245 ) 73g C m-2 yr-1 for the first 15 yr after land use change that corresponds to an estimated 74 ) 22 Tg C yr-1 for the total area of abandoned lands in Russian Federation. Currently, the Russian territory acts as an absolute sink of atmospheric CO2 at a rate about 0.90 Pg C yr-1. Using three different approaches, it was demonstrated that after 1990, the carbon sequestration in Russian soils (0.20 cm layer) has averaged 34 ) 2.2 Tg C yr-1. This soil C forms net biome production (NBP) where carbon lifetime is much longer than in eKyoto forestsf. Thus, the post-agrogenic ecosystems in Russia provide with the additional CO2 sink in NEP and NBP that could annually compensate about 25% of the current fossil fuel emissions in the Russian Federation.

Effects of TGF beta-1 on mouse embryo implantation and expression of H2-D1 and H2-DM

We investigated the mechanism that TGF-beta1 influences the immuno-environment at maternal-fetal interface and affects embryo implantation, using mouse uterine horn injection model. The expression of MHC I antigen (H2-D1) and the chaperone of MHC II antigen (H2-DM) after anti-TGF-beta1 antibody or hrTGF-beta1 treated pregnant mice were examined by real-time PCR, western blotting and immunohistochemistry. The results showed that the number of implanted embryos of anti-TGF-beta1 antibody-treated mice was decreased compared with the control. The expression of H2-D1 and H2-DM on days 6 and 7 treated uteri was increased both at mRNA and protein levels. In hrTGF-beta1 treated group, the expression of H2-D1 and H2-DM protein was decreased, and the number of implanted embryos was slightly increased. Immunohistochemical studies revealed that H2-D1 and H2-DM were mainly localized to the primary decidual zone. The anti-TGF-beta1 antibody and exogenous hrTGF-beta1 treatment altered the intensity of H2-D1 and H2-DM signal but did not change their localization. These observations suggested that injection of anti-TGF-beta1 antibody affected the number of mouse embryo implantation, and regulated the expression of H2-DM and H2-Q10.

Spatial and temporal alterations of phospholipids determined by mass spectrometry during mouse embryo implantation

Molecular events involved in successful embryo implantation are not well understood. In this study, we used MALDI imaging mass spectrometry (IMS) technologies to characterize the spatial and temporal distribution of phospholipid species associated with mouse embryo implantation. Molecular images showing phospholipid distribution within implantation sites changed markedly between distinct cellular areas during days 4-8 of pregnancy. For example, by day 8, linoleate- and docosahexaenoate-containing phospholipids localized to regions destined to undergo cell death, whereas oleate-containing phospholipids localized to angiogenic regions. Arachidonate-containing phospholipids showed different segregation patterns depending on the lipid class, revealing a strong correlation of phosphatidylethanolamines and phosphatidylinositols with cytosolic phospholipase A(2alpha) and cyclooxygenase-2 during embryo implantation. LC-ESI-MS/MS was used to validate MALDI IMS phospholipid distribution patterns. Overall, molecular images revealed the dynamic complexity of lipid distributions in early pregnancy, signifying the importance of complex interplay of lipid molecules in uterine biology and implantation.

Paracrine Signals from the Mouse Conceptus Are Not Required for the Normal Progression of Decidualization

The purpose of this study was to determine whether the conceptus directs the formation of a tight- and adherens-dependent permeability barrier formed by the primary decidual zone and normal progression of decidual cell differentiation during embryo implantation. Four artificial models of decidualization were used, some apparently more physiological than others. The results show that both the formation of the permeability barrier and decidual cell differentiation of three of the artificial models were quite different from that of pregnant uteri. One artificial model of decidualization, namely pseudopregnant animals receiving concanavalin A-coated Sepharose bead transfers on d 2.5 of pseudopregnancy, better recapitulated the decidual changes that occur in the pregnant uterus undergoing decidualization. This included the formation of a primary decidual zone-like permeability barrier and decidual growth. This model also exhibited similar temporal changes of the expression of genes involved in decidualization that are markers of decidual cell differentiation. Overall, the results of this study indicate that some models of inducing decidualization artificially produce responses that are more similar to those occurring in the pregnant uterus, whereas others are quite different. More importantly, the results suggest that concanavalin A-coated Sepharose beads can provide an equivalent stimulus as the trophectoderm to cause the formation of the primary decidual zone permeability barrier.

Vascular Endothelial Growth Factor Receptor 2 (VEGFR-2) Functions to Promote Uterine Decidual Angiogenesis during Early Pregnancy in the Mouse

Implantation of an embryo induces rapid proliferation and differentiation of uterine stromal cells, forming a new structure, the decidua. One salient feature of decidua formation is a marked increase in maternal angiogenesis. Vascular endothelial growth factor (VEGF)-dependent pathways are active in the ovary, uterus, and embryo, and inactivation of VEGF function in any of these structures might prevent normal pregnancy development. We hypothesized that decidual angiogenesis is regulated by VEGF acting through specific VEGF receptors (VEGFRs). To test this hypothesis, we developed a murine pregnancy model in which systemic administration of a receptor-blocking antibody would act specifically on uterine angiogenesis and not on ovarian or embryonic angiogenesis. In our model, ovarian function was replaced with exogenous progesterone, and blocking antibodies were administered prior to embryonic expression of VEGFRs. After administration of a single dose of the anti-VEGFR-2 antibody during the peri-implantation period, no embryos were detected on embryonic d 10.5. The pregnancy was disrupted because of a significant reduction in decidual angiogenesis, which under physiological conditions peaks on embryonic d 5.5 and 6.5. Inactivation of VEGFR-3 reduced angiogenesis in the primary decidual zone, whereas administration of VEGFR-1 blocking antibodies had no effect. Pregnancy was not disrupted after administration of anti-VEGFR-3 or anti-VEGFR-1 antibodies. Thus, the VEGF/VEGFR-2 pathway plays a key role in the maintenance of early pregnancy through its regulation of peri-implantation angiogenesis in the uterine decidua. This newly formed decidual vasculature serves as the first exchange apparatus for the developing embryo until the placenta becomes functionally active.

Expression of secreted frizzled-related protein 4 in the primate placenta

Secreted frizzled-related protein 4 (sFRP4) blocks the Wnt signalling pathway by competitively binding Wnt ligands (frizzled receptors). This pathway is important during development and oncogenesis. It is, however, complex with a large number of interacting proteins, isoforms and receptors. The Wnt signalling pathway has a role in human placental development and implantation, particularly in the trophoblast. Humans and macaque monkeys exhibit a similar remodelling of the decidual spiral arteries. The expression of sFRP4 in human and macaque placentas at different gestational ages have been examined with immunohistochemistry, in-situ hybridization, real-time polymerase chain reaction, and western blotting. This study demonstrates that sFRP4 is expressed predominantly in the villous syncytiotrophoblast and the invasive intermediate cytotrophoblast, and in the amnion. These observational studies suggest that sFRP4 has a role in placental development and implantation, and may be an important factor in the development of the decidual fibrinoid zone, and in trophoblast apoptosis and a band of apoptosis in the underlying decidua deep into the trophoblast.

Consideration on the distribution of the subalpine deciduous broad-leaved forest zone

Consideration on the distribution of the subalpine deciduous broad-leaved forest zone

Body measurement characteristics of the West African Dwarf (WAD) Goat in deciduous forest zone of Southwestern Nigeria

Two hundred and forty four (244) West African Dwarf (WAD) Goats comprising one hundred and sixty (160) females and eighty-four (84) males in five (5) age groups in years (0 - 1, 1 - 2, 2 - 3, 3 - 4 and 4 - 5) for female and two (2) age groups also in years (0 - 1 and 1 - 2) for males were investigated. The aim was to document the body characteristics of the WAD goats in the deciduous forest of Southwest Nigeria. Results showed that the body weights (BDW) for female and male goats averaged 5.97, 10.59, 14.59, 19.23, 20.06 males; 4.33 and 7.55 kg females respectively. The body linear measurements for male and female goats varied between 33.70 and 39.58 cm, 28.98 and 31.50 cm, 25.68 and 30.49 cm, 28.94 and 34.73 cm and 6.47 and 7.72 cm for male goats and 41.53 and 59.51 cm, 37.07 and 53.55 cm, 31.30 and 45.22 cm, 37.08 and 50.23 cm, 9.06 and 13.08 cm for female goats for heart girth (HTG), body length (BDL), height at wither (HTW), rump height (RPH) and sacral pelvic width (SPW), respectively. Age significantly (P 1 and 1 - 2 years, sex significantly (P be predicted accurately from heart girth, sacral pelvic width, body length, wither height and rump height.

Will Stream Periphyton Respond to Increases in Light Following Forecasted Regional Hemlock Mortality?

ABSTRACT The hemlock woolly adelgid invasion is expected to cause widespread mortality of eastern hemlock (Tsuga canadensis) throughout much of New England. Light levels in streams with hemlock riparian zones are anticipated to increase as hemlock trees are replaced by deciduous trees. We sought to: (1) quantify differences in light reaching streams with hemlock and deciduous riparian zones, (2) determine if increases in light result in higher periphyton biomass, and (3) explore the role of macroinvertebrate grazing on periphyton biomass as light increases in an attempt to help predict stream ecosystem responses to hemlock mortality. Light measurements were taken along 100–800 m stream reaches with riparian zones of healthy hemlock and deciduous trees in Massachusetts and Connecticut. In addition, a 2 × 2 factorial experimental design with five replicates was executed on a deciduous reach of Egypt Brook in central Massachusetts, in which light (high light vs. low light) and grazing (high grazing vs. low grazing) were manipulated. Light measurements were significantly higher for streams with deciduous riparian zones than hemlock riparian zones. Periphyton biomass was significantly reduced by controlled shading, but was not influenced by grazer exclusion.