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At least 19 recordsLinked to original sources

PubMed1997

[Studies on the regulation of glucoamylase gene (glaA) expression in A. niger I. The overall analysis and comparison of the expression of glucoamylase in the overproducing strain A. niger T21 and its original strain A. niger 3.795].

Expression of the A. niger T21 and 3.795 glaA gene was investigated with respect to the growth of mycelia, producing of glucoamylase, copy number of glaA gene as well as glucoamylase mRNA level and its stability. Both A. niger T21 and 3.795 produced substantial glucoamylase at the stable phase when their biomass were the same. After incubating for 72 hours, while the biomass remained the same, the glucoamylase produced by T21 was 10-17 times higher than that by 3.795. Northern analysis showed that in the total RNA from T21 4.3-4.4 fold as much glucoamylase mRNA as from 3.795 was determined. This result along with results with regard to copy number of glaA gene and stability of glucoamylase mRNA supported the suggestion that the increased mRNA level of glucoamylase was contributed by the increasing at transcription level. The inconsistancy between the difference of enzyme production (10-17 fold) and that of the mRNA level (4.3-4.4 fold) revealed that some difference at translation exist probably. Furthermore, expression of both T21 and 3.795 glaA gene was regulated by carbon sources, this regulation occurred at transcription level in the same manner and also probably occurred at translation level.

Aspergillus niger↗

PubMed2005

Effects of temperature on the rate of increase of Stomoxys calcitrans and Stomoxys niger niger (Diptera: Muscidae) from La Réunion island.

Adult survival and reproduction were compared between two Stomoxys species that co-occur in La Reunion, the cosmopolitan Stomoxys calcitrans (L.), and the tropical Stomoxys niger niger Macquart. In a first experiment, mean longevity and fecundity were determined at five constant temperatures from 15 to 35 degrees C, after development at the same temperatures. Adult longevity was greatest at 20 degrees C in S. calcitrans and at 15 degrees C in S. niger. Adult S. niger survived longer than adult S. calcitrans, especially at 15 degrees C. At 35 degrees C, all flies died within 3 d. Reproduction occurred only within the 20-30 degrees C range, and S. niger laid more eggs than S. calcitrans. In both species, lifetime fecundity tended to decrease when temperature increased, because of the shortening of the oviposition period. In a second experiment, adults were maintained at 15 degrees C after development at 25 degrees C. The higher temperature during development significantly increased adult longevity in S. calcitrans but not in S. niger. Reproduction occurred at 15 degrees C, with notable fecundity in S. calcitrans (22 eggs per female) but not in S. niger (<1 egg per female). Using previous results on immature survival and developmental time in the two species, several life history parameters were compared at each temperature. Generation time decreased with increasing temperature and was highly similar in both species. Concurrently, the intrinsic rate of increase (r) increased with temperature from 15 to 30 degrees C. At 15 degrees C, r was higher in S. calcitrans, but within the 20-30 degrees C range, r was higher in S. niger. The results suggest 1) S. niger has evolved a strategy of survival without any reproduction during the tropical winter, in contrast with S. calcitrans that breeds more continuously; and 2) S. niger may outnumber S. calcitrans in warm areas, at least when development occurs in media of poor quality.

Animals↗

PubMed2005

Temperature effects on development and survival of two stable flies, Stomoxys calcitrans and Stomoxys niger niger (Diptera: muscidae), in La Réunion Island.

Two stable fly species, Stomoxys calcitrans (L., 1758) and Stomoxys niger niger Macquart, 1851, co-occur in La Reunion, where they are important pests of cattle. The survival and developmental rate of the immature stages were compared at five constant temperatures from 15 to 35 degrees C. In both species, immature survival was highest at 20-25 degrees C and markedly decreased at 15 and 35 degrees C. At the lower temperatures, mortality was observed mainly for S. calcitrans larvae and S. niger eggs. At the higher temperatures, mainly pupae of both species died. At all temperatures, S. calcitrans survived better than S. niger. Developmental time was highly similar in both species, decreasing from 71 d at 15 degrees C to 13 d at 30 degrees C in S. calcitrans and from 69 d at 15 degrees C to 14 d at 30 degrees C in S. niger. Developmental times increased slightly at 35 degrees C. Surprisingly, the tropical S. niger developed slightly faster than the cosmopolitan S. calcitrans at 15-20 degrees C; the reverse was found at higher temperatures. Temperature summation models confirmed that S. niger had a lower developmental threshold than S. calcitrans (11.3 versus 12.2 degrees C) and higher day-degree (DD) requirements to complete development (251 versus 225 DD). Overall, the results suggest that S. calcitrans is better adapted than S. niger, in terms of adult production from eggs, in the temperature range of La Reunion.

Animals↗

PubMed1994

Characterization of an efficient gene cloning strategy for Aspergillus niger based on an autonomously replicating plasmid: cloning of the nicB gene of A. niger.

The development of an improved gene cloning strategy by complementation of mutant alleles in Aspergillus niger is described. The strategy is based on the use of a fungal autonomously replicating vector, pAB4-ARp1. This vector was constructed by the introduction of a previously described sequence involved in autonomous replication (AMA1), into a pyrG integrative vector, pAB4-1. With vector pAB4-ARp1, a 10-100-fold increase in transformation frequency was obtained, as compared to pAB4-1. Furthermore, the transformation frequency of a co-transformed plasmid is also increased using pAB4-ARp1. A. niger transformants containing pAB4-ARp1 are mitotically unstable. Co-transformed plasmids strictly co-segregated with the autonomously replicating vector, as a result of recombination between both vectors. The use of pAB4-ARp1 in gene cloning was demonstrated by the complementation of two linkage group-VII-specific A. niger mutants. Complementation of a lysF mutant was achieved by co-transformation of pAB4-ARp1 with total genomic A. niger DNA ('instant bank'). A nicB-deficient A. niger was complemented by co-transformation with pAB4-ARp1 and an A. niger cosmid library. The complementing DNA was re-isolated from a Nic+ transformant by transforming Escherichia coli with total genomic DNA of this transformant. Gene disruption and genetic analysis was carried out to prove that the previously unknown A. niger nicB gene had been cloned.

Aspergillus niger↗

PubMed1998

Comparison of the thermostability properties of three acid phosphatases from molds: Aspergillus fumigatus phytase, A. niger phytase, and A. niger PH 2.5 acid phosphatase.

Enzymes that are used as animal feed supplements should be able to withstand temperatures of 60 to 90 degrees C, which may be reached during the feed pelleting process. The thermostability properties of three histidine acid phosphatases, Aspergillus fumigatus phytase, Aspergillus niger phytase, and A. niger optimum pH 2.5 acid phosphatase, were investigated by measuring circular dichroism, fluorescence, and enzymatic activity. The phytases of A. fumigatus and A. niger were both denatured at temperatures between 50 and 70 degrees C. After heat denaturation at temperatures up to 90 degrees C, A. fumigatus phytase refolded completely into a nativelike, fully active conformation, while in the case of A. niger phytase exposure to 55 to 90 degrees C was associated with an irreversible conformational change and with losses in enzymatic activity of 70 to 80%. In contrast to these two phytases, A. niger pH 2.5 acid phosphatase displayed considerably higher thermostability; denaturation, conformational changes, and irreversible inactivation were observed only at temperatures of >/=80 degrees C. In feed pelleting experiments performed at 75 degrees C, the recoveries of the enzymatic activities of the three acid phosphatases were similar (63 to 73%). At 85 degrees C, however, the recovery of enzymatic activity was considerably higher for A. fumigatus phytase (51%) than for A. niger phytase (31%) or pH 2.5 acid phosphatase (14%). These findings confirm that A. niger pH 2.5 acid phosphatase is irreversibly inactivated at temperatures above 80 degrees C and that the capacity of A. fumigatus phytase to refold properly after heat denaturation may favorably affect its pelleting stability.

6-Phytase↗

PubMed1990

Cloning and expression of a second Aspergillus niger pectin lyase gene (pelA): indications of a pectin lyase gene family in A. niger.

Using the previously cloned Aspergillus niger N756 pectin lyase D gene as a probe, the corresponding pelD gene has been isolated from a genomic library of the laboratory strain A. niger N400. This gene encodes PLD, previously described as PLI, which is one of the two major pectin lyases isolated from the commercial pectinase preparation Ultrazym. Heterologous hybridization of the A. niger N400 genomic library with the pelD gene led to the isolation of another five genes: pelA, B, C, E, and F. These genes differ in their hybridization patterns with probes containing either the entire pelD gene, or 5' or 3' parts thereof. By partial sequencing, and expression in an A. niger transformant containing multiple copies of the pelA gene, we show that this gene, which hybridizes strongest with the pelD gene, encodes the other major pectin lyase from Ultrazym, PLII.

Amino Acid Sequence↗

PubMed2004

Emergence of Schistosoma mansoni in the Niger River valley, Niger.

Urinary and intestinal schistosomiasis are both endemic in Niger with a dominance of Schistosoma haematobium. This study pointed out the appearance of the infection to S. mansoni in the Niger River valley, where it was until then unknown in Niger. In one year the prevalence increased from 5.9 to 19.5%.

Adolescent↗

PubMed1998

[Research on the regulation of glucoamylase gene(glaA) expression in A. niger. II. Analysis of the function of 5'-regulatory region of A. niger T21 and 3.795 glaA gene].

Two plasmid vectors pXH2 and pGH1 were constructed through the fusion of E. coli hph gene, the report gene and the 5' upstream regions of A. niger T21 and 3.795 respectively, as well as the terminator of A. nidulans trpC gene. The plasmid vectors were than used to transform A. niger T21 to functionally identify those different basic groups between the two 5' upstream regions responsible for high-level expression of the glaA gene. Southern analysis of two transformants XH2C and GH1C revealed that pXH2 and pGH1 were integrated respectively into the chromosome at same site with two copies in tandem array. The level resistant to HmB(3000 micrograms/ml) of XH2C was twice as high as that (1500 micrograms/ml) of GH1C, indicating that the changes of basic groups through mutation result in twice increase of functional level of region responsible for transcription and regulation of A. niger T21 glaA gene compared with that of 3.795.

Aspergillus niger↗

PubMed1991

Structure of the Aspergillus niger pelA gene and its expression in Aspergillus niger and Aspergillus nidulans.

Aspergillus niger pectin lyases are encoded by a multigene family. The complete nucleotide sequence of the pectin lyase PLA-encoding gene pelA has been determined. Comparison of the deduced amino acid sequence with the deduced amino acid sequence of the other characterized pectin lyase, PLD, shows that the proteins share 69% amino acid identity. When grown on media with pectin as the sole carbon source, A. niger transformants containing multiple copies of the pelA gene show raised mRNA levels and overexpression of the gene product PLA compared with the wild-type strain. PLA was purified and characterized. In A. nidulans transformants PLA is also produced in medium containing a high concentration of glucose and no pectin.

Amino Acid Sequence↗

PubMed1990

Expression of the Aspergillus niger glucose oxidase gene in A. niger, A. nidulans and Saccharomyces cerevisiae.

We report the cloning of the Aspergillus niger glucose oxidase gene and its use to elevate glucose oxidase productivity in A. niger by increasing the gene dosage. In addition, the gene has been introduced into A. nidulans where it provides the novel capacity to produce glucose oxidase. A plasmid, in which DNA encoding the mature form of glucose oxidase was preceded by a Saccharomyces cerevisiae secretion signal, effected high-level production of extracellular glucose oxidase in this yeast.

Amino Acid Sequence↗

PubMed1994

Ochratoxin A production by strains of Aspergillus niger var. niger.

In a survey of the occurrence of ochratoxin A (OA)-positive strains isolated from feedstuffs, two of the 19 isolates of Aspergillus niger var. niger that were studied produced OA in 2% yeast extract-15% sucrose broth and in corn cultures. This is the first report of production of OA by this species.

Animals↗

PubMed2002

TMC-256A1 and C1, new inhibitors of IL-4 signal transduction produced by Aspergillus niger var niger TC 1629.

New inhibitors of IL-4 signal transduction, designated as TMC-256A1 and C1, were discovered together with TMC-256B1, a previously known dihydronaphthopyrone, from the fermentation broth of Aspergillus niger var niger TC 1629 by using an IL-4 driven reporter gene assay. Based on spectroscopic analyses, TMC-256A1 and C1 were found to be new members of the naphthopyrone antibiotics. TMC-256A1, B1 and C1 inhibited the IL-4 driven luciferase activity with IC50 values of 25 microM, 30 microM and 1.7 microM, respectively in this assay system. Furthermore, these compounds inhibited the expression of germline C epsilon mRNA with IC50 values of 6.6 microM , 34 microM and 0.31 microM, respectively.

Anti-Bacterial Agents↗

PubMed1996

Increased resistance to 14 alpha-demethylase inhibitors (DMIs) in Aspergillus niger by coexpression of the Penicillium italicum eburicol 14 alpha-demethylase (cyp51) and the A. niger cytochrome P450 reductase (cprA) genes.

In this paper we describe the effects of over-expression of the Penicillium italicum gene encoding eburicol 14 alpha-demethylase (cyp51), in Aspergillus niger strains with one or multiple copies of the gene encoding cytochrome P450 reductase (cprA), on the eburicol 14 alpha-demethylase activity. Eburicol 14 alpha-demethylase activity was determined by measuring the resistance of transformants against some eburicol 14 alpha-demethylase inhibitors (DMIs). DMIs are widely used as fungicides in crop protection and human and veterinarian health care. DMI resistance in a transformant overexpressing both CPR and CYP51 was increased 5-30-fold compared to DMI resistance in the wild type strain, depending on the test compound used. Resistance in this strain was approximately 2-5-fold increased compared to DMI resistance in a transformant that was overexpressing the cyp51 gene but had only the wild type copy of the cprA gene and approximately 3-12-fold increased compared to a strain overexpressing the cprA gene (and having only the wild type copy of the cyp51 gene). These results show the importance of CPR overexpression for increasing cytochrome P450 activities in filamentous fungi.

Aspergillus niger↗

PubMed1963