Über den Flavonoidstoffwechsel während der Samenkeimung

Es wurde das Flavonoidmuster ruhender Samen und 8 bis 10 Tage alter Keimlinge von 18 Pflanzenarten unterschiedlicher taxonomischer Einheiten verglichen. Als allgemeines Ergebnis kann festgestellt werden: In den meisten Samen und in allen Keimlingen liegen neben Zimtsäuren (und Derivaten) Flavonoide, hauptsächlich Quercetin- und Kämpferolglykoside, in unterschiedlicher Anzahl und Menge vor. Das “Ruhemuster” unterscheidet sich allgemein von der Pigmentausstattung junger Keimlinge. Drei typische Gruppen von Pflanzen wurden gefunden, deren Pigmentgehalt und -muster während der Samenkeimung charakteristisch verändert wird.     

Habitat selection by grayling—I. Spawning habitats

Grayling spawning sites were investigated in two French rivers, the Pollon (1 year) and the Suran (2 years) and described by current velocity, water depth, and substrate composition, completed by an assessment of bottom shear stress with FST-hemispheres. A comparison was made between used and available habitats, the latter being characterized by random sampling of 300 m long (Pollon) and 510 m long (Suran) river sections, both including three riffle/pool sequences. Mean velocities observed on spawning sites did not differ significantly between rivers or years (overall mean 48–9 cm s^-1 S.D. = 11.9, range 25.8–91.7 cm s^-1, n =150). Most water depths ranged from 10 to 40 cm in both rivers, but mean depths were significantly different ( P <0.05). Substratum of spawning grounds was dominated by gravel and pebbles (2–64 mm) in both rivers. Most spawning sites (99%) were characterized by a narrow range of hemispheres (nos 9–13), i.e. a range of shear stress of about 5–16 dyn m^-2. In the Pollon, spawners between spawning acts were found in a resting pool located immediately downstream from the spawning area and characterized by slow-flowing water (mainly <20 cm s^-1) and great depth (mainly >60 cm), with cover provided by overhanging branches and tree roots.     

Efficient Evergreen Plant Regeneration of <i>Cinnamomum japonicum</i> Sieb. through <i>in vitro</i> Organogenesis

Cinnamomum japonicum Sieb. is an excellent roadside tree and medicinal tree species with considerable ornamental and economic value. In this study, we successfully developed a large-scale micropropagation protocol for C. japonicum for the first time. Sterilized shoots were excised and used as explants for shoot induction on several basal media, supplemented with different concentrations of plant growth regulators (PGRs), such as Thidiazuron (TDZ), N⁶ -Benzyladenine (6-benzylaminopurine) (BA), α-naphthaleneacetic acid (NAA) and Gibberellic acid (GA₃). After comparison, the most efficient medium for shoot regeneration was 1/2 Murashige and Skoog (MS) medium containing 0.5 mg L^–1 BA, 0.05 mg L^–1 NAA and 0.2 mg L^–1 GA₃, which resulted in an average number of induced shoots per explant and shoot length of 5.2 and 1.62 cm at 28 d, respectively. Then, elongated adventitious shoots were transferred to induce roots. 86.7% of shoots was able to root on 1/2 MS medium supplemented with 0.5 mg L^–1 NAA and 0.1 mg L^–1 BA. The earliest rooting time observed was after 21 d and the average root length was up to 3.3 cm after 28 d. Our study shows that C. japonicum can be successfully regenerated through de novo organogenesis, which lays a foundation for future transformation research on this tree.     

The benthos of Øvre Heimdalsvatn: Introduction

For the purpose of benthic studies Øvre Heimdalsvatn was divided into three depth zones. These were the exposed zone (from the shore down to 1–2 m depth), the macrophytic zone (1–2 m to 5–5.5 m depth) and the non-macrophytic zone (5–5.5 m to 13 m). The reasons for this division and the main characteristics of each zone, including the substrata present, are given.     

Role of Organic Amendments to Mitigate Cd Toxicity and Its Assimilation in <i>Triticum aestivum</i> L.

In soil biota, higher and enduring concentration of heavy metals like cadmium (Cd) is hazardous and associated with great loss in growth, yield, and quality parameters of most of the crop plants. Recently, in-situ applications of eco-friendly stabilizing agents in the form of organic modifications have been utilized to mitigate the adverse effects of Cd-toxicity. This controlled experiment was laid down to appraise the imprints of various applied organic amendments namely poultry manure (PM), farmyard manure (FYM), and sugarcane press mud (PS) to immobilize Cd in polluted soil. Moreover, phytoavailability of Cd in wheat was also accessed under an alkaline environment. Results revealed that the addition of FYM (5–10 ton ha^-1 ) in Cd-contaminated soil significantly increased germination rate, leaf chlorophyll content, plant height, spike length, biological and grain yield amongst all applied organic amendments. Moreover, the addition of FYM (5–10 ton ha^-1 ) also reduced the phytoavailability of Cd by 73–85% in the roots, 57–83% in the shoots, and 81–90% in grains of wheat crop. Thus, it is affirmed that incorporation of FYM (5–10 ton ha^-1 ) performed better to enhance wheat growth and yield by remediating Cd. Thus, the application of FYM (5–10 ton ha^-1 ) reduced the toxicity induced by Cd to plants by declining its uptake and translocation as compared to all other applied organic amendments to immobilize Cd under sandy alkaline polluted soil.     

Angiotensin-(1–7) through AT2 receptors mediates tyrosine hydroxylase degradation via the ubiquitin–proteasome pathway

Hypothalamic norepinephrine (NE) release regulates arterial pressure by altering sympathetic nervous system activity. Because angiotensin (Ang) (1–7) decreases hypothalamic NE release and this effect may be correlated with a diminished NE synthesis, we hypothesize that Ang-(1–7) down-regulates tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamines biosynthesis. We investigated the effect of Ang-(1–7) on centrally TH activity and expression. TH activity was evaluated by the release of tritiated water from ³H- l -tyrosine. TH expression and phosphorylation were determined by western blot. Hypothalami from normotensive or spontaneously hypertensive rats pre-incubated with Ang-(1–7) showed a significant decrease in TH specific activity. Ang-(1–7) caused a decrease in TH phosphorylation at Ser19 and Ser40 residues. The heptapeptide induced a decrease in TH expression that was blocked by an AT₂ receptor antagonist and not by an AT₁ or Mas receptor antagonist, suggesting the involvement of AT₂ receptors. The proteasome inhibitor MG132 blocked the Ang-(1–7)-mediated TH reduction. In addition, Ang-(1–7) increased the amount of TH–ubiquitin complexes, indicating that the Ang-(1–7)-mediated TH degradation involves ubiquitin conjugation prior to proteasome degradation. We conclude that Ang-(1–7) down-regulates TH activity and expression centrally leading to a decrease in the central NE system activity.     

Mechanism of docosahexaenoic acid-induced inhibition of in vitro Aβ1–42 fibrillation and Aβ1–42-induced toxicity in SH-S5Y5 cells

The mechanism of the effect of docosahexaenoic acid (DHA; C22:6, n -3), one of the essential brain nutrients, on in vitro fibrillation of amyloid β (Aβ_1–42), Aβ_1–42-oligomers and its toxicity imparted to SH-S5Y5 cells was studied with the use of thioflavin T fluorospectroscopy, laser confocal microfluorescence, and transmission electron microscopy. The results clearly indicated that DHA inhibited Aβ_1–42-fibrill formation with a concomitant reduction in the levels of soluble Aβ_1–42 oligomers. The polymerization (into fibrils) of preformed oligomers treated with DHA was inhibited, indicating that DHA not only obstructs their formation but also inhibits their transformation into fibrils. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis (12.5%), Tris–Tricine gradient(4–20%) gel electrophoresis and western blot analyses revealed that DHA inhibited at least 2 species of Aβ_1–42 oligomers of 15–20 kDa, indicating that it hinders these on-pathway tri/tetrameric intermediates during fibrillation. DHA also reduced the levels of dityrosine and tyrosine intrinsic fluorescence intensity, indicating DHA interrupts the microenvironment of tyrosine in the Aβ_1–42 backbone. Furthermore, DHA protected the tyrosine from acrylamide collisional quenching, as indicated by decreases in Stern–Volmer constants. 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide-reduction efficiency and immunohistochemical examination suggested that DHA inhibits Aβ_1–42-induced toxicity in SH-S5Y5 cells. Taken together, these data suggest that by restraining Aβ_1–42 toxic tri/tetrameric oligomers, DHA may limit amyloidogenic neurodegenerative diseases, Alzheimer's disease.     

A thermotolerant and high acetic acid-producing bacterium Acetobacter sp. I14–2

A thermotolerant bacterium with high production of acetic acid was isolated from spoiled banana in Taiwan. The isolate, I14–2 ,was considered to be an Acetobacter sp. according to phenotypic and chemotaxonomic characteristics. Optimal cultural conditions for Acetobacter sp. I14–2 to produce acetic acid were studied under cultivation in a medium containing 2 mg l⁻¹ acetic acid and 5% ethanol at 30 °C. Acetic acid productivity by Acetobacter sp. I14–2 was almost two and three times the amount produced by Acet. aceti IFO3283 and Acetobacter sp. CCRC 12326, respectively. The isolate retained 22% residual acetic acid-producing activity after 3 d incubation in a medium containing 8% ethanol, and produced acetic acid in a medium containing 10 g l⁻¹ acetic acid. This bacterium is thermotolerant and retained 97% and 68% of acetic acid-producing activity after 3 d incubation at 35 °C and 37 °C, respectively, compared with that when incubated at 30 °C.     

Aerobic degradation and dechlorination of 2–chlorophenol, 3-chlorophenol and 4-chlorophenol by a Pseudomonas pickettii strain

F. FAVA, P.M. ARMENANTE AND D. KAFKEWITZ. 1995. A Gram-negative aerobic bacterium capable of using 2–chlorophenol (2–CP), 3–chlorophenol (3–CP) and 4–chlorophenol (4–CP) as sole carbon sources was isolated and characterized. The bacterium, designated LD1, was identified to be a Pseudomonas pickettii strain. LD1 was able to totally degrade and dechlorinate 2–CP (initial concentration: 1.51 mmol I^-1), 3–CP (initial concentration: 0.57 mmol I^-1) and 4–CP (initial concentration: 0.75 mmol I^-1) within 30, 30 and 40 h of incubation, respectively, under growing-cell batch conditions. LD1 was also found to be able to metabolize chlorocatechols in growing- and resting-cell conditions. This suggests that the bacterium degrades monochlorophenols through a chlorocatechol pathway. In addition, LD1 was found to be capable of readily metabolizing other organic compounds such as phenol, benzoic acid, hydroxybenzoic acids and hydroquinone.
Because of the broad spectrum of monochlorophenols and organic compounds that LD1 can degrade, this bacterium appears to have the potential for being successfully used in the biotreatment of wastewaters and in soil decontamination.     

Some Eugregarines (Sporozoa, Apicomplexa) from the Stored Fruit Beetle, Oryzaephilus mercator Fauv. (Coleoptera) from India

Morphology and life history of 3 cephaline gregarines found in the gut of the pest of stored fruit, Oryzaephilus mercator. are described. Of these 3, 2 are new species. The 3 species are (1) Hirmocystis minuta (Ishii, 1914) (LP TL = 1:7 – 1:22, WP/WD = 1:1, 6–1:7); (2) Amsotobus indicus n. sp. (LP/TL = 1:3–1:6, WP/WD = 1:1 – 1:1.3); (3) Leidyana oryzaephili n. sp. (LP/TL = 1:2 – 1:12; WP/WD = 1:1–1:1.6).     

Licht- und ultraviolettmikroskopische Beobachtungen an Schließzellen nach ihrer Reaktion auf verschiedene Umweltbedingungen1

• 1 . Zellkerne, Chloroplasten und Sphärosomen der Schließzellen lassen sich in der Regel schon im sichtbaren Licht mit dem DIK-Verfahren sehr gut darstellen
• 2 . Wichtige Strukturunterschiede an Zellkern, Chloroplasten und Vakuolen wurden in geöffneten und geschlossenen lebenden Schließzellen mit dem UV-Mikroskop (ZEISS) gefunden
• 3 . Die UV-Absorption der Flavonoide bzw. phenolischen Pflanzeninhaltsstoffe in geschlossenen Stomata ist hoch, die der geöffneten gering (Abbau?). Wegen der großen Menge an Flavonoiden im Zellsaft der Freilandpflanzen wird eine Veränderung ihres Absorptionsvermögens nur schwer nachweisbar sein
• 4 . Hohe Temperaturen (bis 41 °C) oder Lagerung der Epidermen in Paraffinöl führen nach etwa 24 Stunden zu einem Verschwinden der Flavonoidabsorption und zu einer Schädigung der Stomata
• 5 . Wassermangel durch Welken des Blattes führt zu einer reversiblen Konvexplasmolyse der Schließzellen. Die Flavonoidabsorption bleibt dabei weitgehend erhalten

     

Immunohistochemical Localization of G Protein β1, β2, β3, β4, β5, and γ3 Subunits in the Adult Rat Brain

Abstract: The regional distributions of the G protein β subunits (Gβ1–β5) and of the Gγ3 subunit were examined by immunohistochemical methods in the adult rat brain. In general, the Gβ and Gγ3 subunits were widely distributed throughout the brain, with most regions containing several Gβ subunits within their neuronal networks. The olfactory bulb, neocortex, hippocampus, striatum, thalamus, cerebellum, and brainstem exhibited light to intense Gβ immunostaining. Negative immunostaining was observed in cortical layer I for Gβ1 and layer IV for Gβ4. The hippocampal dentate granular and CA1–CA3 pyramidal cells displayed little or no positive immunostaining for Gβ2 or Gβ4. No anti-Gβ4 immunostaining was observed in the pars compacta of the substantia nigra or in the cerebellar granule cell layer and Purkinje cells. Immunoreactivity for Gβ1 was absent from the cerebellar molecular layer, and Gβ2 was not detected in the Purkinje cells. No positive Gγ3 immunoreactivity was observed in the lateral habenula, lateral septal nucleus, or Purkinje cells. Double-fluorescence immunostaining with anti-Gγ3 antibody and individual anti-Gβ1–β5 antibodies displayed regional selectivity with Gβ1 (cortical layers V–VI) and Gβ2 (cortical layer I). In conclusion, despite the widespread overlapping distributions of Gβ1–β5 with Gγ3, specific dimeric associations in situ were observed within discrete brain regions.     

黑毛石斛和长距石斛的光合特性

以黑毛组的黑毛石斛(Dendrobium williamsonii)和长距石斛(D. longicornu)为材料, 对其光合生理特性进行了系统研究。2种石斛叶片的解剖结构为异面叶, 气孔仅分布在下表面, 具气孔盖, 叶脉维管束鞘不含叶绿体, 无花环型结构。2种石斛的光强、CO₂浓度和温度的响应研究表明, 它们的光补偿点(LCP)和光饱和点(LSP)分别为5–10 μmol·m⁻²·s⁻¹和800–900μmol·m⁻²·s⁻¹,表观量子效率为0.02; CO₂补偿点和CO₂饱和点分别为80–90 μmol·mol⁻¹和800 μmol·mol⁻¹, 羧化效率在0.015–0.021之间; 光合作用的最适温度为28–30°C。光合特性的研究表明, 2种石斛的净光合速率(P_n)日变化均呈双峰型曲线, 首峰出现在12:00, 最大光合速率为5 μmolCO2·m⁻²·s⁻¹, 次峰出现在15:00, 夜间不吸收CO₂。2种石斛叶片的叶绿素a/叶绿素b比值在2.51–2.66之间。酶活性的测定结果表明, 2种石斛的PEPCase活性极低, 但RuBPCase和GO酶活性较高。以上的研究结果均表明, 黑毛石斛和长距石斛光合作用碳同化途径属C3植物类型, 具有半阴生植物的特点。     

欧美108杨细根形态及垂直分布对水氮耦合措施的响应

合理高效的水肥集约经营是有效地提高速生丰产林生产力的重要途径。细根是植物吸收水肥和维持生长的主要器官, 了解细根形态及其分布对水肥耦合措施的响应机制有助于解释树木生长和吸收水肥能力的差异性。该文基于水氮耦合措施对欧美108杨(Populus × euramericana ‘Guariento’)幼林表土层(0–30 cm)细根形态及分布的影响研究, 在连续两年的水氮管理后, 开展了欧美108杨0–60 cm土层细根形态及垂直分布对水氮耦合响应的研究。田间设计3个灌溉水平(灌溉土壤水势起始阈值为–75 kPa、–50 kPa、–25 kPa)和3个养分水平(施N 150 g·tree^–1·a^–1、300 g·tree^–1·a^–1、450 g·tree^–1·a^–1), 组合成9个水氮耦合处理, 另设1个对照处理(CK)。研究结果表明: (1)垂直方向上, 各处理细根生物量密度、表面积和平均直径均表现为10–20 cm土层最大(该层生物量密度占0–60 cm土层总生物量的27%–37%), 随后在30–60 cm土层逐层递减; 根长密度则随土壤深度的加深而逐层递减, 0–10 cm土层显著大于其他土层(该层根长密度占0–60 cm土层总根长密度的33%–45%)。(2) 6个土层的细根生物量密度、根长密度和平均直径均表现为高水高氮(D3F3)和中水高氮(D2F3) 2个处理间差异不显著, 但均显著高于其他处理, 其中, D3F3处理6个土层生物量密度是对照的3.12–47.74倍; 细根表面积则是D3F3处理显著高于其他处理, 是CK的4.36–30.57倍。(3)连续的水氮耦合管理措施不会改变细根的垂直分布格局(各处理均具有与CK一致的分布格局), 但在第二个生长季, 欧美108杨细根的整体分布随着林龄的增加趋于深层化; 另外, 中水高氮的耦合处理也可有效地促进细根的生长, 这种水氮需求水平与第一个生长季内需高水高氮才可显著促进其生长的特性不同。欧美108杨细根在第2个生长季主要分布于0–20 cm土层, 9个水氮耦合处理中, 除低水低氮处理外, 其他处理各细根形态指标值均显著高于CK, 这种差异性在浅土层更为显著, 而在深土层表现出相对较小的差异。当灌溉量一定时(尤其中、高灌溉水平), 增加施氮量可显著促进细根生长, 但当施氮量一定时(尤其低、中氮水平), 增加灌溉量对细根生长的促进效果不显著, 即欧美108杨细根生长趋肥性强于向水性。     

Responses of the fine root morphology and vertical distribution of Populus × euramericana ‘Guariento’ to the coupled effect of water and nitrogen

Aims Irrigation and fertilization have great potentials to enhance yield in forest plantations. The integrated effect of water and nitrogen management on fine roots morphology and distribution of Populus × euramericana ‘Guariento’, however, remains unclear. The objective of this study was to evaluate the effect of water and nitrogen addition on fine root morphology and distribution in poplar plantations for developing the best water and nitrogen strategy for promoting fine root. Methods The soil core method was used to quantify the morphology and distribution of fine roots in the 0–60 cm in a poplar plantation with surface dripping irrigation and fertilization technologies. The experiment included nine treatments, which were a combination of three irrigation treatments where dripping irrigation was applied when soil water potential (ψ_soil) reached –75, –50, or –25 kPa, and three fertilization treatments at nitrogen additions of 150, 300, or 450 g·tree–1·a–1, respectively). A control plot with non-irrigation and non-fertilizationtreatment in growing season (CK) was also included in the study. Important findings The fine roots biomass density, fine root surface area density, average root diameter in all treatments were mainly found at 0–10 cm and 10–20 cm depths, with root biomass density in the 10–20 cm of 1.03 to 1.21 times of that in the 0–10 cm, 1.25 to 1.80 times of that in the 20–30 cm, 1.62 to 22.10 times of that in the 30–40 cm, 2.77 to 54.35 times of that in the 40–50 cm, and 6.48 to 293.09 times of that in the 50–60 cm. The root biomass density in the 10–20 cm accounted for 27%–37% of the total biomass density in the top 60 cm. For root biomass density and average diameter, there were no significant differences between 0–10 cm and 10–20 cm depths, and between 40–50 cm and 50–60 cm depths. Fine roots in the irrigation and fertilization treatments were significantly higher than that of the CK, except the D1F1 treatment (i.e., with low water and low nitrogen level). Additionally, fine roots in the D2F3 treatment (i.e., with intermedia irrigation and high nitrogen level) and the D3F3 treatment (i.e., with high water and high nitrogen level) were significantly higher than those in other treatments, but not significantly different between D2F3 and D3F3. Compared with the CK, the fine roots biomass density in six soil layers were significantly enhanced at 359%, 388%, 328%, 3823%, 4774% and 2866%, respectively, for the treatment with high water and high nitrogen levels. The vertical distributions of fine roots appeared not affected by the interaction of irrigation and nitrogen addition. However, the surface dripping irrigation and fertilization treatments increased fine roots significantly. Finally, we found that the response of fine root growth and distribution was stronger to fertilization than to the irrigation in this poplar plantation.     

A recombinant peptide based on Pf EMP-1 blocks and reverses adhesion of malaria-infected red blood cells to CD36 under flow

During falciparum malaria infection, severe complications ensue because parasitized red blood cells (PRBCs) adhere to endothelial cells and accumulate in the microvasculature. At the molecular level, adhesion is mediated by interaction of Plasmodium falciparum erythrocyte membrane protein 1 ( Pf  EMP-1) on the PRBC surface with receptors on the surface of endothelial cells, including CD36. We have shown that a recombinant 179-residue subfragment of Pf  EMP-1 (rC1-2[1–179]), which encompasses the CD36-binding region, inhibits and reverses adhesion of PRBCs to CD36 under physiologically relevant flow conditions. rC1-2[1–179] inhibited adhesion in a concentration-dependent manner over the range 100 pM to 2 μM, with up to 99% of adhesion blocked at the highest concentration tested. The antiadhesive activity of rC1-2[1–179] was not strain specific and almost totally ablated adhesion of four different parasite lines. Furthermore, rC1-2[1–179] showed remarkable ability to progressively reverse adhesion when flowed over adherent PRBCs for 2 h. The effect of rC1-2[1–179] was, however, specific for CD36-mediated adhesion and had no effect on adhesion mediated by CSA. Interference with binding of PRBCs to the vascular endothelium using rC1-2[1–179] or smaller organic mimetics may be a useful therapeutic approach to ameliorate severe complications of falciparum malaria.     

Purification and properties of the endocellular β-glucosidase of Candida cacaoi Buckley and Van Uden CBS 2020

D. DRIDER, P. POMMARES, P. CHEMARDIN, A. ARNAUD AND P. GALZY. 1993. The endocellular enzyme β-glucosidase of Candida cacaoi was purified by ion-exchange chromatography and gel filtration. The molecular weight was 220 ± 10 kDa; its optimum pH was between 4 and 5.5 and its optimum temperature was 60C. This enzyme was active against soluble glucosides tested with β(1–2), β(1–3), β(1–4) and even α(1–4) and α(1–6) and was inhibited by D-glucono-δ-lactone. The enzyme was constitutive but its synthesis was repressed by glucose.     

β25–35 Alters Calcium Homeostasis and Induces Neurotoxicity in Cerebellar Granule Cells

Abstract: We studied the neurotoxic effects of β25–35 amyloid fragment (β25–35) on cerebellar granule cells and the intracellular mechanisms involved. Treatment for 3 days with peptide greatly reduced the survival of 1 day in vitro (DIV) cultures kept in 5 m M KCl but slightly modified the survival of 25 m M KCl-cultured cerebellar granule cells. We also studied the effect of glutamate on survival of undifferentiated cerebellar granules. We report no neurotoxic effect of glutamate on 3-DIV-treated cultures; whereas in β25–35-pretreated cells, a significant glutamate toxicity was observed. Treatment of 6-DIV cells with β25–35, performed with 25 m M KCl, induced a late but significant neurotoxic effect after 5 days of exposure, and death occurred within 8 days. Differentiated cerebellar granule cells were also sensitive to glutamate-related neurotoxicity, and this effect was enhanced by β25–35 pretreatment. To study the molecular mechanisms underlying the neurotoxic effects of β25–35, changes in calcium homeostasis after glutamate stimulation were evaluated in control and β25–35-treated cells. β25–35 did not affect basal [Ca²⁺]_i but modified glutamate-induced [Ca²⁺]_i increase, causing a sustained plateau phase that persisted even after the removal of the agonist. These results show that β25–35 induces neurotoxicity in cerebellar granule cells and that this effect is related to modifications in the control of calcium homeostasis.     

The trophic basis of production of the macroinvertebrate community of a southeastern U.S.A. blackwater stream

The trophic basis of production of the macroinvertebrate communities at three sites on a second-order, low gradient blackwater stream in southeastern U.S.A. was determined. The sampling sites were located above, within and below a low-flow swamp system. From 47–64% of macroinvertebrate production was supported by FPOM at the three sites, with dependence on FPOM being greatest at the swamp site. Algae (filamentous species and diatoms) supported 15–31% of production, indicating that algae can be of considerable importance even in fully canopied headwater streams. The production of some collector-gatherers including Stenonema modestum (55%), Hexagenia munda (58%) and Baetis spp. (78%), was supported predominantly by algae. Algae also supported 61–79% of Hydropsychidae production and 68% of Simuliidae production. Animal material supported 16–26% of macroinvertebrate production at the three sites. CPOM was of minor direct importance to the macroinvertebrate community of this headwater stream, supporting only 1–3% of macroinvertebrate production. Shredders ingested only 1–3 g m⁻² y⁻¹ of CPOM, or about 1% of the annual direct leaf fall to this stream. Assuming a 10% assimilation efficiency for CPOM, shredders produced <3 g m⁻² y⁻¹ of FPOM through CPOM processing, this being approximately 2 orders of magnitude less than reported for high gradient headwater streams. These results indicate that low-order coastal plain streams vary somewhat from the River Continuum Concept in that they exhibit little utilization of and dependence on CPOM as a direct energy source. Only the smallest first-order streams and especially the extensive floodplains may be the functional headwaters of these stream systems.