TEMPERATURE-SENSITIVE FLOCCULATION DURING GROWTH OF SACCHAROMYCES CEREVISIAE

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Anatomical aspects of the lacrimal gland of the tufted capuchin (Cebus apella)

In the tufted capuchin (Cebus apella) the main lacrimal gland is composed of 2 distinct portions with an intraorbital and extraorbital localisation, interconnected by a bridge of glandular tissue which crosses the lateral orbital wall through the lateral orbital fissure located in the sphenozygomatic suture. The intraorbital lacrimal gland is flattened and extremely thin, with a variable outline. It lies on the upper and outer third of the globe of the eye, and the aponeurosis and the belly of the lateral rectus muscle, extending antero-posteriorly from the upper lateral angle of the orbit midway along the orbital cavity. The extraorbital lacrimal gland is compact, halfmoon-shaped, with 3 surfaces, 3 borders and 2 extremities. It lies in the temporal fossa between the temporalis muscle and the temporal surface of the zygomatic bone, fitting into a depression in this bone, and totally surrounded by adipose tissue. The secretory cells have a flocculent appearance and either low or high density. They possess a basal region containing the nucleus and rich in granular endoplasmic reticulum, and an apical region filled with secretory granules varying in size, form and density.

Efficient flotation of yeast cells grown in batch culture

A fast flotation assay was used to select new floating yeast strains. The flotation ability did not seem to be directly correlated to total extracellular protein concentration of the culture. However, the hydrophobicity of the cell was definitely correlated to the flotation capacity. The Saccharomyces strains (FLT strains) were highly hydrophobic and showed an excellent flotation performance in batch cultures without additives (flotation agents) and with no need for a special flotation chamber or flotation column. A stable and well-organized structure was evident in the dried foam as shown by scanning electron microscopy which revealed its unique structure showing mummified cells (dehydrated) attached to each other. The attachment among the cells and the high protein concentration of the foams indicated that proteins might be involved in the foam formation. The floating strains (strains FLT) which were not flocculent and showed no tendency to aggregate, were capable of growing and producing ethanol in a synthetic medium containing high glucose concentration as a carbon source. The phenomenon responsible for flotation seems to be quite different from the flocculation phenomenon. (C) 1996 John Wiley & Sons, Inc.

Ultrastructure of the salivary glands of Pachycondyla (=Neoponera) villosa (Fabricius) (Formicidae: Ponerinae): Functional changes during the last larval instar

The cells of secretory region of the salivary glands of Pachycondyla (=Neoponera) villosa at the time of enzyme production presents the basal cellular membranes profusely folded and the intercellular junctional membranes present a few enlarged spaces. The rough endoplasmic reticulum and the Golgi bodies shift from being flat and small vesicular cisternae to enlarged vesicular cisternae according to the cell physiological state and characterize an asynchronic cell cycle. Enzymes are released into the lumen by microapocrine secretion. The stage of silk production is detected after a behavioral act, when the nurse worker separates the mature larva. At this time, the salivary gland cells present only one physiological state (synchronized secretory cycle): this state was characterized by basal cellular membrane poorly folded, intercellular junctions presenting some small spaces, rough endoplasmic reticulum compounded by flat cistenae, enlarged Golgi bodies with fibrous material inside and a few secretory vesicles containing silk, which undergo exocytosis. The silk in the lumen shows 2 forms: tactoid and flocculent material.

Desempenho de reator anaeróbio de fluxo ascendente alimentado com lodo de estação de tratamento de água e esgoto sanitário

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Emprego de técnica dedicada de análise de imagem na avaliação do produto GT no desempenho da floculação

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Skeletal muscle degeneration and regeneration after injection of bothropstoxin-II, a phospholipase A2 isolated from the venom of the snake Bothrops jararacussu

A myotoxic phospholipase A2, named bothropstoxin II (BthTX-II), was isolated from the venom of the South American snake Bothrops jararacussu and the pathogenesis of myonecrosis induced by this toxin was studied in mice. BthTX-II induced a rapid increase in plasma creatine kinase levels. Histological and ultrastructural observations demonstrate that this toxin affects muscle fibers by first disrupting the integrity of plasma membrane, as delta lesions were the earliest morphological alteration and since the plasma membrane was interrupted or absent in many portions. In agreement with this hypothesis, BthTX-II released peroxidase entrapped in negatively charged multilamellar liposomes and behaved as an amphiphilic protein in charge shift electrophoresis, an indication that its mechanism of action might be based on the interaction and disorganization of plasma membrane phospholipids. Membrane damage was followed by a complex series of morphological alterations in intracellular structures, most of which are probably related to an increase in cytosolic calcium levels. Myofilaments became hypercontracted into dense clumps which alternated with cellular spaces devoid of myofibrillar material. Later on, myofilaments changed to a hyaline appearance with a more uniform distribution. Mitochondria were drastically affected, showing high amplitude swelling, vesiculation of cristae, formation of flocculent densities, and membrane disruption. By 24 hr, abundant polymorphonuclear leucocytes and macrophages were observed in the interstitial space as well as inside necrotic fibers. Muscle regeneration proceeded normally, as abundant myotubes and regenerating myofibers were observed 7 days after BthTX-II injection. By 28 days regenerating fibers had a diameter similar to that of adult muscle fibers, although they presented two distinctive features: central location of nuclei and some fiber splitting. This good regenerative response may be explained by the observation that BthTX-II does not affect blood vessels, nerves, or basal laminae. © 1991.

The yeast STM1 protein binds G*G multiplex nucleic acids in vitro and associates with ribosomes in vivo

The formation of triple helical, or triplex DNA has been suggested to occur in several cellular processes such as transcription, replication, and recombination. Our laboratory previously found proteins in HeLa nuclear extracts and in S. cerevisiae whole cell extracts that avidly bound a Purine-motif (Pu) triplex probe in gel shift assays, or EMSA. In order to identify a triplex DNA-binding protein, we used conventional and affinity chromatography to purify the major Pu triplex-binding protein in yeast. Peptide microsequencing and data base searches identified this protein as the product of the STM1 gene. Confirmation that Stm1p is a Pu triplex-binding protein was obtained by EMSA using both recombinant Stm1p and whole cell extracts from stm1Δ yeast. Stm1p had previously been identified as G4p2, a G-quartet DNA- and RNA-binding protein. To study the cellular role and identify the nucleic acid ligand of Stm1p in vivo, we introduced an HA epitope at either the N- or C-terminus of Stm1p and performed immunoprecipitations with the HA.11 mAb. Using peptide microsequencing and Northern analysis, we positively identified a subset of both large and small subunit ribosomal proteins and all four rRNAs as associating with Stm1p. DNase I treatment did not affect the association of Stm1p with ribosomal components, but RNase A treatment abolished the association with all ribosomal proteins and RNA, suggesting this association is RNA-dependent. Sucrose gradient fractionation followed by Western and EMSA analysis confirmed that Stm1p associates with intact 80S monosomes, but not polysomes. The presence of additional, unidentified RNA in the Stm1p-immunoprecipitate, and the absence of tRNAs and elongation factors suggests that Stm1p binds RNA and could be involved in the regulation of translation. Immunofluorescence microscopy data showed Stm1p to be located throughout the cytoplasm, with a specific movement to the bud during the G2 phase of the cell cycle. A dramatically flocculent, large cell phenotype is observed when Stm1p has a C-terminal HA tag in a protease-deficient strain background. When STM1 is deleted in this background, the same phenotype is not observed and the deletion yeast grow very slowly compared to the wild-type. These data suggest that STM1 is not essential, but plays a role in cell growth by interacting with an RNP complex that may contain G*G multiplex RNA. ^

(Table 1) Distribution of Cretaceous-Tertiary benthic foraminifers in ODP Hole 129-802A

Reworked shallow-water larger and deep-water calcareous benthic foraminifers were recovered from foraminiferal packstones and nannofossil chalks in Hole 802A. The autochthonous zeolitic pelagic claystone is characterized by late Campanian abyssal agglutinated foraminifers that allow correlation with the North Atlantic and the adjacent Pigafetta Basin. Assemblages of DendrophryalRhizammina in graded beds within the zeolitic claystone indicate reworking through entrainment in the flocculent E layer of turbidites, rather than recolonization following a biosiliceous event. Background sedimentation of the claystone took place below the carbonate compensation depth. The nannofossil chalk contains reworked lower bathyal to abyssal calcareous foraminifers of late Paleocene to early Miocene age. The topmost bed of the nannofossil chalk unit commences with an algal foraminiferal packstone containing Lepidocyclina sumatrensis, Heterostegina borneensis, Amphistegina hauerina, Asterigerina marshallana, and A. tentoria, which indicate that the source area was a shallow-water reef and allow the bed to be dated as early Miocene. The absence of obviously younger planktonic microfossils in the graded bed indicates that the resedimentation event was generally contemporaneous with original deposition and took place during an early Miocene global sea-level highstand. An early Miocene shallow-water assemblage is also seen in the graded beds at the base of a volcaniclastic turbidite sequence overlying the nannofossil chalks. Resedimentation of this unit was associated with volcanic activity some distance away.

Short-term changes in phosphorus storage in an oligotrophic Everglades wetland ecosystem receiving experimental nutrient enrichment

Natural, unenriched Everglades wetlands are known to be limited by phosphorus (P) and responsive to P enrichment. However, whole-ecosystem evaluations of experimental P additions are rare in Everglades or other wetlands. We tested the response of the Everglades wetland ecosystem to continuous, low-level additions of P (0, 5, 15, and 30 μg L−1 above ambient) in replicate, 100 m flow-through flumes located in unenriched Everglades National Park. After the first six months of dosing, the concentration and standing stock of phosphorus increased in the surface water, periphyton, and flocculent detrital layer, but not in the soil or macrophytes. Of the ecosystem components measured, total P concentration increased the most in the floating periphyton mat (30 μg L−1: mean = 1916 μg P g−1, control: mean = 149 μg P g−1), while the flocculent detrital layer stored most of the accumulated P (30 μg L−1: mean = 1.732 g P m−2, control: mean = 0.769 g P m−2). Significant short-term responses of P concentration and standing stock were observed primarily in the high dose (30 μg L−1 above ambient) treatment. In addition, the biomass and estimated P standing stock of aquatic consumers increased in the 30 and 5 μg L−1 treatments. Alterations in P concentration and standing stock occurred only at the upstream ends of the flumes nearest to the point source of added nutrient. The total amount of P stored by the ecosystem within the flume increased with P dosing, although the ecosystem in the flumes retained only a small proportion of the P added over the first six months. These results indicate that oligotrophic Everglades wetlands respond rapidly to short-term, low-level P enrichment, and the initial response is most noticeable in the periphyton and flocculent detrital layer.

Phosphorus enrichment effects on interactions among the ecosystem components in a long-hydroperiod oligotrophic marsh in Everglades National Park

Hydrology and a history of oligotrophy unite the massive landscape comprising freshwater marsh in Everglades National Park. With restoration of water flow to the Everglades, phosphorus (P) enrichment, both from agricultural and domestic sources, may increase nutrient load to the marsh ecosystem. Previous research of P enrichment of Everglades soil, periphyton, and macrophytes revealed each of these ecosystem components responds to increased P loads with increased production and nutrient content. Interactions among these ecosystem components and how P affects the magnitude and direction of interaction are poorly understood and are the focus of my research. Here I present results of a two-year, two-factor experiment of P enrichment and manipulation in Everglades National Park. I quantified biomass, nutrient content, and production for periphyton and macrophyes and found macrophyte removal drives change in nutrient content, biomass, and production of periphyton. Periphyton removal did not appear to control macrophyte dynamics. Soil chemical and physical characteristics were explained primarily by site differences but there was an enrichment effect of soil porewater nitrite + nitrate, nitrite, and soluble reactive phosphorus. Flocculent materials production and depth were significantly affected by macrophyte removal where depth and production were significantly greater with the no macrophyte treatment. The dominant macrophyte of the marsh, Eleocharis cellulosa, increased more in the unenriched marsh than in the enriched marsh. The combination of these findings suggests that dynamics in floc and periphyton are controlled primarily by the presence of periphyton and that this relationship is significantly affected by low-level P enrichment. These results may be valuable in their application to both managers and policy makers who are involved in the Everglades restoration process. ^

Local biomass control on the composition and reactivity of particulate organic matter in aquatic environments

Freshwater ecosystems have been recognized as important components of the global carbon cycle, and the flux of organic matter (OM) from freshwater to marine environments can significantly affect estuarine and coastal productivity. The focus of this study was the assessment of carbon dynamics in two aquatic environments, namely the Florida Everglades and small prairie streams in Kansas, with the aim of characterizing the biogeochemistry of OM. In the Everglades, particulate OM (POM) is mostly found as a layer of flocculent material (floc). While floc is believed to be the main energy source driving trophic dynamics in this oligotrophic wetland, not much is known about its biogeochemistry. The objective of this study was to determine the origin/sources of OM in floc using biomarkers and pigment-based chemotaxonomy to assess specific biomass contributions to this material, on a spatial (freshwater marshes vs. mangrove fringe) and seasonal (wet vs. dry) scales. It was found that floc OM is derived from the local vegetation (mainly algal components and macrophyte litter) and its composition is controlled by seasonal drivers of hydrology and local biomass productivity. Photo-reactivity experiments showed that light exposure on floc resulted in photo-dissolution of POC with the generation of significant amounts of both dissolved OM (DOM) and nutrients (N & P), potentially influencing nutrient dynamics in this ecosystem. The bio-reactivity experiments determined as the amount and rate of CO2 evolution during incubation were found to vary on seasonal and spatial scales and were highly influenced by phosphorus limitation. Not much is known on OM dynamics in small headwater streams. The objective of this study was to determine carbon dynamics in sediments from intermittent prairie streams, characterized by different vegetation cover for their watershed (C4 grasses) vs. riparian zone (C3 plants). In this study sedimentary OM was characterized using a biomarker and compound specific carbon stable isotope approach. It was found that the biomarker composition of these sediments is dominated by higher plant inputs from the riparian zone, although inputs from adjacent prairie grasses were also apparent. Conflicting to some extent with the River Continuum Concept, sediments of the upper reaches contained more degraded OM, while the lower reaches were enriched in fresh material deriving from higher plants and plankton sources as a result of hydrological regimes and particle sorting.

Exploring the role of large predators in marsh food webs: evidence for a behaviorally-mediated trophic cascade

The influence of large predators on lower trophic levels in oligotrophic, structurally complex, and frequently disturbed aquatic environments is generally thought to be limited. We looked for effects of large predators in two semi-permanent, spikerush-dominated marshes by excluding large fish (>12 mm body depth) and similarly sized herpetofauna from 1 m2 cages (exclosures) for 2 weeks. The exclosures allowed for colonization by intermediate (in size and trophic position) consumers, such as small fish, shrimp, and crayfish. Exclosures were compared to control cages that allowed large fish to move freely in and out. At the end of the experiment, intermediate-consumer densities were higher in exclosures than in controls at both sites. Decapod crustaceans, especially the riverine grass shrimp (Palaemonetes paludosus), accounted for the majority of the response. Effects of large fish on shrimp were generally consistent across sites, but per capita effects were sensitive to estimates of predator density. Densities of intermediate consumers in our exclosures were similar to marsh densities, while the open controls had lower densities. This suggests that these animals avoided our experimental controls because they were risky relative to the surrounding environment, while the exclosures were neither avoided nor preferred. Although illuminating about the dynamics of open-cage experiments, this finding does not influence the main results of the study. Small primary consumers (mostly small snails, amphipods, and midges) living on floating periphyton mats and in flocculent detritus (“floc”) were less abundant in the exclosures, indicative of a trophic cascade. Periphyton mat characteristics (i.e., biomass, chlorophyll a, TP) were not clearly or consistently affected by the exclosure, but TP in the floc was lower in exclosures. The collective cascading effects of large predators were consistent at both sites despite differences in drought frequency, stem density, and productivity.

Interactions between nutrient availability and hydroperiod shape macroinvertebrate communities in Florida Everglades marshes

Hydroperiod and nutrient status are known to influence aquatic communities in wetlands, but their joint effects are not well explored. I sampled floating periphyton mat and flocculent detritus (floc) infaunal communities using 6-cm diameter cores at short- and long-hydroperiod and constantly inundated sites across a range of phosphorus (P) availability (total phosphorus in soil, floc and periphyton). Differences in community structure between periphyton and floc microhabitats were greater than any variation attributable to hydroperiod, P availability, or other spatial factors. Multivariate analyses indicated community structure of benthic-floc infauna was driven by hydroperiod, although crowding (no. g−1 AFDM) of individual taxa showed no consistent responses to hydroperiod or P availability. In contrast, community structure of periphyton mat infauna was driven by P availability, while densities of mat infauna (no. m−2) were most influenced by hydroperiod (+correlations). Crowding of mat infauna increased significantly with P availability in short-hydroperiod marshes, but was constant across the P gradient in long-hydroperiod marshes. Increased abundance of floating-periphyton mat infauna with P availability at short-hydroperiod sites may result from a release from predation by small fish. Community structure and density were not different between long-hydroperiod and constantly inundated sites. These results have implications for the use of macroinvertebrates as indicators of water quality in wetlands and suggest the substrate sampled can influence interpretation of ecological responses observed in these communities.

Phosphorus cycling and partitioning in an oligotrophic Everglades wetland ecosystem: a radioisotope tracing study

1. Our goal was to quantify short-term phosphorus (P) partitioning and identify the ecosystem components important to P cycling in wetland ecosystems. To do this, we added P radiotracer to oligotrophic, P-limited Everglades marshes. 32PO4 was added to the water column in six 1-m2 enclosed mesocosms located in long-hydroperiod marshes of Shark River Slough, Everglades National Park. Ecosystem components were then repeatedly sampled over 18 days. 2. Water column particulates (>0.45 μm) incorporated radiotracer within the first minute after dosing and stored 95–99% of total water column 32P activity throughout the study. Soluble (<0.45 μm) 32P in the water column, in contrast, was always <5% of the 32P in surface water. Periphyton, both floating and attached to emergent macrophytes, had the highest specific activity of 32P (Bq g−131P) among the different ecosystem components. Fish and aquatic macroinvertebrates also had high affinity for P, whereas emergent macrophytes, soil and flocculent detrital organic matter (floc) had the lowest specific activities of radiotracer. 3. Within the calcareous, floating periphyton mats, 81% of the initial 32P uptake was associated with Ca, but most of this 32P entered and remained within the organic pool (Ca-associated = 14% of total) after 1 day. In the floc layer, 32P rapidly entered the microbial pool and the labile fraction was negligible for most of the study. 4. Budgeting of the radiotracer indicated that 32P moved from particulates in the water column to periphyton and floc and then to the floc and soil over the course of the 18 day incubations. Floc (35% of total) and soil (27%) dominated 32P storage after 18 days, with floating periphyton (12%) and surface water (10%) holding smaller proportions of total ecosystem 32P. 5. To summarise, oligotrophic Everglades marshes exhibited rapid uptake and retention of labile 32P. Components dominated by microbes appear to control short-term P cycling in this oligotrophic ecosystem.