Eukaryotic Cell

SYNOPSIS. An age-autolyzed culture of Chroomonas salina, grown under cool-white light with glycerol, produced waxy lipid constituting about 44% of total matter harvested. This lipid was composed of 87% wax ester, 9% triglyceride, 3% polar lipid and 1% hydrocarbon. The major wax ester species were identified by total carbon number as C26(28%), C28(35%), C30(15%). The main fatty acid components of the wax esters were 12:0 (39%), 14:0 (30%), 16:0 (14%), while the main alcohols were 14:0 (53%) and 16:0 (40%). The hydrocarbon fraction showed saturated paraffins ranging from C17 to C33, with odd-numbered chain components predominating. No polyunsaturated components were detected in the wax ester or hydrocarbon fractions. This is the first record of wax ester production by a cryptomonad or a marine phytoplankter.

We have developed a simple, efficient procedure for the long term freezing of Tetrahymena thermophila in liquid nitrogen. This technique yields excellent recovery of viable cells with all strains tested and does not require the use of a controlled rate low temperature freezer. To optimize the freezing technique, we have examined the effects of varying a number of parameters, including the physiological state of the cells prior to freezing, the time of exposure to cryoprotectant, and the rate of freezing and thawing. The frequency of viable cell recovery following freezing using this technique has been tested for a variety of different cell lines.

A velvet multisubunit complex was recently detected in the filamentous fungus Penicillium chrysogenum , the major industrial producer of the β-lactam antibiotic penicillin. Core components of this complex are P. chrysogenum VelA (PcVelA) and PcLaeA, which regulate secondary metabolite production, hyphal morphology, conidiation, and pellet formation. Here we describe the characterization of PcVelB, PcVelC, and PcVosA as novel subunits of this velvet complex. Using yeast two-hybrid analysis and bimolecular fluorescence complementation (BiFC), we demonstrate that all velvet proteins are part of an interaction network. Functional analyses using single- and double-knockout strains clearly indicate that velvet subunits have opposing roles in the regulation of penicillin biosynthesis and light-dependent conidiation. PcVelC, together with PcVelA and PcLaeA, activates penicillin biosynthesis, while PcVelB represses this process. In contrast, PcVelB and PcVosA promote conidiation, while PcVel...

RESUMEN En éste trabajo se realizó el reconocimiento a los integrantes del dominio eukarya (protozoos, algas, hongos). En el caso de hongos, protozoos y algas se hizo un reconocimiento detallado de esto donde se pudo evidenciar sus tipos y el porqué de sus características físicas y biológicas. Además, para el fungi se aplicó la técnica del repique para Trichoderma, y se aisló otros hongos a partir de una gran variedad de productos naturales como el banano, aguacate, arepa, pan, fresa, mora, semillas de cannabis, semillas de naranja, entre otros. A partir del aislamiento, se logró observar las estructuras principales que facilitan ver la taxonomía del microorganismo y ésto se pudo realizar a través del microscopio. ABSTRACT In this work the recognition to members of the eukarya domain (protozoa, algae, fungi) was performed. In the case of fungi, protozoa and algae made a detailed analysis of where this was evident why their types and their physical and biological characteristics recognition. In addition to the fungi technique peal for Trichoderma it was applied, and other fungi was isolated from a variety of natural products such as bananas, avocado, corn bread, bread, strawberry, blackberry, cannabis seeds, orange seeds, among others. From isolation, it was possible to observe the main structures that facilitate see the taxonomy of the organism and this could be done through the microscope.

ABSTRACT
In this work the recognition to members of the eukarya domain (protozoa, algae, fungi) was performed. In the case of fungi, protozoa and algae made a detailed analysis of where this was evident why their types and their physical and biological characteristics recognition. In addition to the fungi technique peal for Trichoderma it was applied, and other fungi was isolated from a variety of natural products such as bananas, avocado, corn bread, bread, strawberry, blackberry, cannabis seeds, orange seeds, among others. From isolation, it was possible to observe the main structures that facilitate see the taxonomy of the organism and this could be done through the microscope.

This study demonstrates the utility of Lifeact for the investigation of actin dynamics in Neurospora crassa and also represents the first report of simultaneous live-cell imaging of the actin and microtubule cytoskeletons in filamentous fungi. Lifeact is a 17-amino-acid peptide derived from the nonessential Saccharomyces cerevisiae actin-binding protein Abp140p. Fused to green fluorescent protein (GFP) or red fluorescent protein (TagRFP), Lifeact allowed live-cell imaging of actin patches, cables, and rings in N. crassa without interfering with cellular functions. Actin cables and patches localized to sites of active growth during the establishment and maintenance of cell polarity in germ tubes and conidial anastomosis tubes (CATs). Recurrent phases of formation and retrograde movement of complex arrays of actin cables were observed at growing tips of germ tubes and CATs. Two populations of actin patches exhibiting slow and fast movement were distinguished, and rapid (1.2 um/s) saltatory transport of patches along cables was observed. Actin cables accumulated and subsequently condensed into actin rings associated with septum formation. F-actin organization was markedly different in the tip regions of mature hyphae and in germ tubes. Only mature hyphae displayed a subapical collar of actin patches and a concentration of F-actin within the core of the Spitzenkörper. Coexpression of Lifeact-TagRFP and beta-tubulin–GFP revealed distinct but interrelated localization patterns of F-actin and microtubules during the initiation and maintenance of tip growth.

ABSTRACT. Nucleariid amoebae are naked amoebae, generally characterized by a spherical or sometimes flattened body with radiating filopodia. Most species preferentially consume algal prey or cyanobacteria. Phylogenetic analyses of the small-subunit rRNA coding regions from four nucleariid amoebae place these species near the origin of the animal-fungal divergence, together with the choanofiagellate-Corallochytrium and the ichthyosporean clades. The species Nuclearia delicatula, N. moebiusi, and N. simplex form a monophyletic group, while ATCC 30864, tentatively but possibly incorrectly assigned to Nuclearia sp., represents a separate line of descent. These nucleariids are unrelated to the lineage containing the testate filose amoebae (Testaceafilosia). Our findings expand the morphological and phylogenetic diversity of protists at the animal-fungal divergence.

... monarch butterfly Danaus plexippus (L.) and the THzorida queen butterfly D. gilippus berenice (Cramer) are 2 of 5 species in the genus Danaus (Nymphalidae: Danainae) that occur in the New World. ... These characters place it in the genus Oph-ryocystis Schneider (7, 8 ) 1884. ...

ABSTRACT. A quantitative technique for the assessment of sporozoite infectivity in vivo, using intra-cecal inoculation of Eimeria tenella sporozoites, has been developed. Evaluation of the infection using cecal lesion scores and oocyst counts showed that this technique should be useful for the quantitation of sporozoite viability and thus for the anti-sporozoite activity of different treatments prior to inoculation. Pre-treatment of sporozoites with heat-inactivated hyperimmune antisera neutralized sporozoite infectivity in vivo and indicated that antibodies in the absence of complement inhibited sporozoite infectivity in vivo.

ABSTRACT The first known fossil slime mold with part of the plasmodium preserved, from Eocene-Oligocene amber of the northern Dominican Republic, is described here. We assign it to the myxomycetes on the basis of its cytoplasmic structure. The paleoecological and evolutionary importance of this fossil is briefly discussed.

The vacuolar membrane ATPase (V-ATPase) is a protein complex that utilizes ATP hydrolysis to drive protons from the cytosol into the vacuolar lumen, acidifying the vacuole and modulating several key cellular response systems in Saccharomyces cerevisiae. To study the contribution of V-ATPase to the biology and virulence attributes of the opportunistic fungal pathogen Candida albicans, we created a conditional mutant in which VMA3 was placed under the control of a tetracycline-regulated promoter (tetR-VMA3 strain). Repression of VMA3 in the tetR-VMA3 strain prevents V-ATPase assembly at the vacuolar membrane and reduces concanamycin A-sensitive ATPase-specific activity and proton transport by more than 90%. Loss of C. albicans V-ATPase activity alkalinizes the vacuolar lumen and has pleiotropic effects, including pH-dependent growth, calcium sensitivity, and cold sensitivity. The tetR-VMA3 strain also displays abnormal vacuolar morphology, indicative of defective vacuolar membrane fis...

TheBlastocladiella emersoniilife cycle presents a number of drastic biochemical and morphological changes, mainly during two cell differentiation stages: germination and sporulation. To investigate the transcriptional changes taking place during the sporulation phase, which culminates with the production of the zoospores, motile cells responsible for the dispersal of the fungus, microarray experiments were performed. Among the 3,773 distinct genes investigated, a total of 1,207 were classified as differentially expressed, relative to time zero of sporulation, at at least one of the time points analyzed. These results indicate that accurate transcriptional control takes place during sporulation, as well as indicating the necessity for distinct molecular functions throughout this differentiation process. The main functional categories overrepresented among upregulated genes were those involving the microtubule, the cytoskeleton, signal transduction involving Ca2+, and chromosome organ...

Variable phenotypes have been identified forEntamoebaspecies.Entamoeba histolyticais invasive and causes colitis and liver abscesses but only in ∼10% of infected individuals; 90% remain asymptomatically colonized.Entamoeba dispar, a closely related species, is avirulent. To determine the extent of genetic diversity amongEntamoebaisolates and potential genotype-phenotype correlations, we have developed anE. histolyticagenomic DNA microarray and used it to genotype strains ofE. histolyticaandE. dispar. On the basis of the identification of divergent genetic loci, all strains had unique genetic fingerprints. Comparison of divergent genetic regions allowed us to distinguish betweenE. histolyticaandE.dispar, identify novel genetic regions usable for strain and species typing, and identify a number of genes restricted to virulent strains. Among the fourE. histolyticastrains, a strain with attenuated virulence was the most divergent and phylogenetically distinct strain, raising the intrigu...

Hemoglobin degradation during the asexual cycle of Plasmodium falciparum is an obligate process for parasite development and survival. It is established that hemoglobin is transported from the host erythrocyte to the parasite digestive vacuole (DV), but this biological process is not well characterized. Three-dimensional reconstructions made from serial, thin-section, electron micrographs of untreated, trophozoite stage P. falciparum infected erythrocytes (IRBC) or IRBC treated with different pharmacological agents provide new insight into the organization and regulation of the hemoglobin transport pathway. Hemoglobin internalization commences with the formation of cytostomes from localized, electron-dense collars at the interface of the parasite plasma- and parasitophorous vacuolar- membranes. The cytostomal collar does not function as a site of vesicle fission, but rather serves to stabilize the maturing cytostome. We provide the first evidence that hemoglobin transport to the DV ...

Marine algae of the genus Nannochloropsis are promising producers of biofuel precursors and nutraceuticals and are also harvested commercially for aquaculture feed. We have used quick-freeze, deep-etch electron microscopy, Fourier transform infrared spectroscopy, and carbohydrate analyses to characterize the architecture of the Nannochloropsis gaditana (strain CCMP 526) cell wall, whose recalcitrance presents a significant barrier to biocommodity extraction. The data indicate a bilayer structure consisting of a cellulosic inner wall (~75% of the mass balance) protected by an outer hydrophobic algaenan layer. Cellulase treatment of walls purified after cell lysis generates highly enriched algaenan preparations without using the harsh chemical treatments typically used in algaenan isolation and characterization. Nannochloropsis algaenan was determined to comprise long, straight-chain, saturated aliphatics with ether cross-links, which closely resembles the cutan of vascular plants. Ch...

We have characterized a phosphoinositide phospholipase C (PI-PLC) from Trypanosoma brucei procyclic forms (PCF). The protein contains a domain organization characteristic of typical PI-PLCs, such as X and Y catalytic domains, an EF-hand calcium-binding motif, and a C2 domain, but lacks a pleckstrin homology (PH) domain. In addition, TbPI-PLC contains an N-terminal myristoylation consensus sequence only found in trypanosomatid PI-PLCs. A peptide containing this N-terminal domain fused to green fluorescent protein (GFP) was targeted to their plasma membrane. TbPI-PLC enzymatic activity was stimulated by Ca(2+) concentrations below cytosolic levels in the parasite, suggesting that the enzyme is constitutively active. TbPI-PLC hydrolyzes both phosphatidylinositol (PI) and phosphatidylinositol 4, 5-bisphosphate (PIP2), with higher affinity for PIP2. We found that modification of a single amino acid in the EF-hand motif greatly affected its Ca(2+) sensitivity and substrate preference demo...