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91.
Sid Ahmed Hammouda Dietrich Kadolsky Mohammed Adaci Fateh Mebrouk Mustapha Bensalah M’hammed Mahboubi Rodolphe Tabuce 《Pal?ontologische Zeitschrift》2017,91(1):85-112
Terrestrial gastropods occur in many North African localities in Eocene continental deposits. Here we analyse the faunal assemblage from the Hamada de Méridja Formation in southwestern Algeria, dated as Early to Middle Eocene on the basis of charophytes. The assemblage consists of three closely related species that to date have been classified either in the extant Madagascan genus Leucotaenius v. Martens, 1860, or in the SW European Eocene genera Romanella Jodot, 1957 and Vicentinia Jodot, 1957. This is rejected for shell morphological and phylogeographical reasons, and a new classification as Maghrebiola gen. nov. is proposed. Maghrebiola is tentatively placed in the South American family Strophocheilidae, as species from the Early Eocene Itaboraí Basin of Brazil, currently placed in the genus Eoborus Klappenbach and Olazarri, 1970 in the family Strophocheilidae, superfamily Acavoidea, have a very similar shell habitus. This record possibly extends the known geographical range of the Strophocheilidae into the African continent during the Eocene. Immigration of this stock into North Africa during the Cretaceous via a still existing plate connection is assumed. An attribution of Maghrebiola to the African family Achatinidae is unlikely for shell morphological reasons despite certain habitus similarities, although the Priabonian genera Arabicolaria and Pacaudiella from Oman most likely belong into this family, and not to the Vidaliellidae as originally proposed. Possible causes for the very low diversity of the assemblage are mainly unfavourable living conditions, i.e. a relatively dry climate resulting in sparse vegetation and only occasional presence of water bodies, which may have had increased salinities, accounting for the lack of freshwater mollusks. The absence of any competing large gastropods may possibly have facilitated high intraspecific variability leading to sympatric occurrence of three closely related species, due to the animals occupying a wide range of available ecological niches. As the species discussed here have also been attributed to the genera Romanella and Vicentinia in the Vidaliellidae, we provide an appendix with annotated characterisations of most genera of the Vidaliellidae and list the nominal species assigned to them. This family is tentatively placed in the South American superfamily Orthalicoidea; its stock would have similarly immigrated from South America, but have successfully colonized mainly SW Europe, with only one Eocene species [Romanella kantarensis (Jodot, 1936)] recognized in Algeria. 相似文献
92.
Fusarium fujikuroi associated with stem rot of red‐fleshed dragon fruit (Hylocereus polyrhizus) in Malaysia 下载免费PDF全文
M. Masratul Hawa I. Nurul Faziha M.N. Nik Mohamad Izham Z. Latiffah 《The Annals of applied biology》2017,170(3):434-446
Stem rot was recorded as one of serious diseases of red‐fleshed dragon fruit, (Hylocereus polyrhizus), in Malaysia. Fusarium fujikuroi was recovered from stem rot lesion of H. polyrhizus and the species was identified using TEF1‐α sequence and mating study. From maximum likelihood phylogenetic tree using combined TEF1‐α and β‐tubulin sequences, the F. fujikuroi isolates from stem rot were grouped according to three geographical locations, namely Peninsular Malaysia, Sabah and Sarawak. Phylogenetic analysis indicated that F. fujikuroi isolates from stem rot of H. polyrhizus were clustered separately from F. fujikuroi isolates from rice because of intraspecific variation. From amplification of MAT allele‐specific primers, 20% of the isolates carried MAT‐1 allele while 80% carried MAT‐2 allele. From isolates that carried MAT‐1 allele, 65% crossed‐fertile with MP‐C (mating population of F. fujikuroi) tester strain while for MAT‐2 allele, 56% crossed‐fertile with MP‐C. None of the isolates were identified as MP‐D (mating population of F. proliferatum). Pathogenicity test conducted on 40 representative isolates showed that the stem rot symptoms were similar with the symptoms observed in the field, and can be categorized as low, moderate and high aggressiveness, which indicated variation in pathogenicity and virulence among the isolates. This study provides novel findings regarding Fusarium species associated with stem rot of H. polyrhizus and indicated that F. fujikuroi as a new causal pathogen of the disease. 相似文献
93.
En route to economical eco‐friendly solvent system in enhancing sustainable recovery of poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) copolymer 下载免费PDF全文
Nik Murniati Nik Man Irdahayu Kannusamy Shantini Kai‐Hee Huong Sevakumaran Vigneswari Nursolehah Abdul Aziz Mohd. Noor Mohd. Azizan Al‐Ashraf Abdullah Amirul 《Engineering in Life Science》2017,17(9):1050-1059
Separation of poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) [P(3HB‐co‐4HB)] from bacterial cell matter is a critical step in the downstream process with respect to material quality and eco‐balance as P(3HB‐co‐4HB) is widely used for biomedical applications. Therefore, an efficient and eco‐based extraction of P(3HB‐co‐4HB) using a combination of NaOH and Lysol in digesting the non‐polymeric cell material (NPCM) digestion is developed. The NaOH and Lysol show synergistic influence on the copolymer extraction at a high purity and recovery of 97 and 98 wt% respectively. The optimized cell digestion method was found applicable to a vast batch of cells containing copolymers from various 4HB monomer compositions. At the largest extraction volume of 100 L, P(3HB‐co‐4HB) with a purity of 89 wt% was extracted with a maximum recovery of 90 wt%. The method developed has also eliminated the cell pretreatment step. The extraction method developed in this research has not only produced an economic and efficient copolymer recovery but has also retained the copolymer quality, in term of its molecular weight and thermal properties. It demonstrates a practical and promising downstream processing method in recovering the copolymer effectively from the bacterial biomass. 相似文献
94.
Jie Liu Min Deng Huan Guo Sharif Raihan Jingyun Luo Yuancheng Xu Xiaofei Dong Jianbing Yan 《植物学报(英文版)》2015,57(11):943-953
Genome information from model species such as rice can assist in the cloning of genes in a complex genome,such as maize.Here,we identified a maize ortholog of rice GS5 that contributes to kernel development in maize.The genomewide association analysis of the expression levels of ZmGS5,and 15 of its 26 paralogs,identified a trans-regulator on chromosome 7,which was a BAKi-like gene.This gene that we named as ZmBAK1-7 could regulate the expression of ZmGS5 and three of the paralogs.Candidate-gene association analyses revealed that these five genes were associated with maize kernel development-related traits.Linkage analyses also detected that ZmGSs and ZmBAK1-7 co-localized with mapped QTLs.A transgenic analysis of ZmGS5 in Arabidopsis thaliana L.showed a significant increase in seed weight and cell number,suggesting that ZmGS5 may have a conserved function among different plant species that affects seed development. 相似文献
95.
In cell therapy protocols, many tissues were proposed as a source of mesenchymal stem cells (MSC) isolation. So far, bone marrow (BM) has been presented as the main source of MSC despite the invasive isolation procedure related to this source. During the last years, the umbilical cord (UC) matrix was cited in different studies as a reliable source from which long term ex vivo proliferating fibroblasts were isolated but with contradictory data about their immunophenotype, gene expression profile, and differentiation potential. Hence, an interesting question emerged: Are cells isolated from cord matrix (UC-MSC) different from other MSCs? In this review, we will summarize different studies that isolated and characterized UC-MSC. Considering BM-MSC as gold standard, we will discuss if UC-MSC fulfill different criteria that define MSC, and what remain to be done in this issue. 相似文献
96.
Ammari M Jeljeli M Jeljeli M Maaroufi K Roy V Sakly M Abdelmelek H 《Electromagnetic biology and medicine》2008,27(2):185-196
The present work investigated the behavioral effects of a moderate exposure (1 h per day for 5 consecutive days) to a static magnetic field (SMF, 128 mT) in male rats. SMF effects were evaluated in two sets of control and SMF-exposed rats. One set of animals was used for evaluation of SMF potential effects on emotional behaviors in the elevated plus maze and in the open field. The other set of animals was tested for learning and memory abilities in different procedures of the Morris water maze task. We found no significant difference between control and SMF-exposed rats in anxiety tests. However, the ratio of open arms time in the plus maze was reduced by half in SMF-exposed rats. In the Morris water maze, SMF-exposed rats were partially impaired during the initial learning task as well as in the retention task at one week. We conclude that static magnetic field exposure altered emotional behaviors in the plus maze and led to cognitive impairments, or at least to substantial attention disorders, in the Morris water maze. 相似文献
97.
Benata H Mohammed O Noureddine B Abdelbasset B Abdelmoumen H Muresu R Squartini A El Idrissi MM 《Systematic and applied microbiology》2008,31(5):378-386
A total of 274 bacterial strains were isolated from the root nodules of Prosopis juliflora, growing in two arid soils of the eastern area of Morocco. A physiological plate screening allowed the selection of 15 strains that could tolerate NaCl concentrations between 175 and 500 mM. These were compared with 15 strains chosen from among the ones which did not tolerate high salinity. The diversity of strains was first assessed by rep-PCR amplification fingerprinting using BOXA1R and ERIC primers. An analysis of the PCR-amplified 16S rDNA gene digestion profiles using five endonucleases indicated the presence of different lineages among the taxa associated with P. juliflora nodules in the soils studied. Nucleotide sequencing of the small subunit rRNA gene and BLAST analysis showed that P. juliflora could host at least six bacterial species in this region and that the identity of those associated with high salt tolerance was clearly distinct from that of the salt-sensitive ones. Among the former, the first type displayed 99% similarity with different members of the genus Sinorhizobium, the second 97% similarity with species within the genus Rhizobium, while the third ribosomal type had 100% homology to Achromobacter xylosoxidans. Within the salt-sensitive isolates the prevailing type observed showed 98% similarity with Rhizobium multihospitium and R. tropici, a second type had 98% similarity to R. giardinii, and a further case displayed 97% colinearity with the Ensifer group including E. maghrebium and E. xericitae. All of the thirty strains encompassing these types re-nodulated P. juliflora in microbiologically controlled conditions and all of them were shown to possess a copy of the nodC gene. This is the first report detecting the betaproteobacterial genus Achromobacter as nodule-forming species for legumes. The observed variability in symbiont species and the abundance of nodulation-proficient strains is in line with the observation that the plant always appears to be nodulated and efficiently fixing nitrogen in spite of a wide range of soil and environmental conditions. 相似文献
98.
Nadiawati Alias Nor Muhammad Mahadi Abdul Munir Abdul Murad Farah Diba Abu Bakar Nik Azmi Nik Mahmood Rosli Md Illias 《World journal of microbiology & biotechnology》2009,25(4):561-572
A gene encoding endochitinase from Trichoderma virens UKM-1 was cloned and expressed in E. coli BL21 (DE3). Both the endochitinase gene and its cDNA sequences were obtained. The endochitinase gene encodes 430 amino acids
from an open reading frame comprising of 1,690 bp nucleotide sequence with three introns. The endochitinase was expressed
as soluble and active enzyme at 20°C when induced with 1 mM IPTG. Maximum activity was observed at 4 h of post-induction time.
SDS-PAGE showed that the purified endochitinase exhibited a single band with molecular weight of 42 kDa. Biochemical characterization
of the enzyme displayed a near neutral pH characteristic with an optimum pH at 6.0 and optimum temperature at 50°C. The enzyme
is stable between pH 3.0–7.0 and is able to retain its activity from 30 to 60°C. The presence of Mg2+ and Ca2+ ions increased the enzyme activity up to 20%. The purified enzyme has a strong affinity towards colloidal chitin and low
effect on ethyl cellulose and D-cellubiose which are non-chitin related substrates. HPLC analysis from the chitin hydrolysis
showed the release of (GlcNAc)3, (GlcNAc)2 and GlcNAc, in which (GlcNAc)2 was the main product. 相似文献
99.
Coxiella burnetii Shedding Routes and Antibody Response after Outbreaks of Q Fever-Induced Abortion in Dairy Goat Herds 下载免费PDF全文
Elodie Rousset Mustapha Berri Benoit Durand Philippe Dufour Myriam Prigent Thibault Delcroix Anne Touratier Annie Rodolakis 《Applied microbiology》2009,75(2):428-433
Q fever is a zoonosis caused by Coxiella burnetii, a bacterium largely carried by ruminants and shed into milk, vaginal mucus, and feces. The main potential hazard to humans and animals is due to shedding of bacteria that can then persist in the environment and be aerosolized. The purpose of this study was to evaluate shedding after an outbreak of Q fever abortion in goat herds and to assess the relationship with the occurrence of abortions and antibody responses. Aborting and nonaborting goats were monitored by PCR for C. burnetii shedding 15 and 30 days after the abortion episodes. PCR analysis of all samples showed that 70% (n = 50) of the aborting and 53% (n = 70) of the nonaborting goats were positive. C. burnetii was shed into vaginal mucus, feces, and milk of 44%, 21%, and 38%, respectively, of goats that aborted and 27%, 20%, and 31%, respectively, of goats that delivered normally. Statistical comparison of these shedding results did not reveal any difference between these two groups. PCR results obtained for the vaginal and fecal routes were concordant in 81% of cases, whereas those for milk correlated with only 49% of cases with either vaginal or fecal shedding status. Serological analysis, using enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence assay (IFA), and complement fixation tests, showed that at least 24% of the seronegative goats shed bacteria. Positive vaginal and fecal shedding, unlike positive milk shedding, was observed more often in animals that were weakly positive or negative by ELISA or IFA. Two opposite shedding trends were thus apparent for the milk and vaginal-fecal routes. Moreover, this study showed that a nonnegligible proportion of seronegative animals that delivered normally could excrete C. burnetii. 相似文献
100.
Nik A. B. N. Mahmood Esther Biemans-Oldehinkel Bert Poolman 《The Journal of biological chemistry》2009,284(21):14368-14376
We have previously shown that the C-terminal cystathionine β-synthase
(CBS) domains of the nucleotide-binding domains of the ABC transporter OpuA,
in conjunction with an anionic membrane surface function, act as sensor of
internal ionic strength (Iin). Here, we show that a
surface-exposed cationic region in the CBS module domain is critical for ion
sensing. The consecutive substitution of up to five cationic residues led to a
gradual decrease of the ionic strength dependence of transport. In fact, a
5-fold mutant was essentially independent of salt in the range from 0 to 250
mm KCl (or NaCl), supplemented to medium of 30 mm
potassium phosphate. Importantly, the threshold temperature for transport was
lowered by 5–7 °C and the temperature coefficient
Q10 was lowered from 8 to ∼1.5 in the 5-fold mutant,
indicating that large conformational changes are accompanying the CBS-mediated
regulation of transport. Furthermore, by replacing the anionic C-terminal tail
residues that extend the CBS module with histidines, the transport of OpuA
became pH-dependent, presumably by additional charge interactions of the
histidine residues with the membrane. The pH dependence was not observed at
high ionic strength. Altogether the analyses of the CBS mutants support the
notion that the osmotic regulation of OpuA involves a simple biophysical
switching mechanism, in which nonspecific electrostatic interactions of a
protein module with the membrane are sufficient to lock the transporter in the
inactive state.In their natural habitats microorganisms are often exposed to changes in
the concentration of solutes in the environment
(1). A sudden increase in the
medium osmolality results in loss of water from the cell, loss of turgor, a
decrease in cell volume, and an increase in intracellular osmolyte
concentration. Osmoregulatory transporters such as OpuA in Lactococcus
lactis, ProP in Escherichia coli, and BetP in
Corynebacterium glutamicum diminish the consequences of the osmotic
stress by mediating the uptake of compatible solutes upon an increase in
extracellular osmolality
(2–4).
For the ATP-binding cassette
(ABC)5 transporter
OpuA, it has been shown that the system, reconstituted in proteoliposomes, is
activated by increased concentrations of lumenal ions (increased internal
ionic strength) (2,
5,
6). This activation is
instantaneous both in vivo and in vitro and only requires
threshold levels of ionic osmolytes. Moreover, the ionic threshold for
activation is highly dependent of the ionic lipid content (charge density) of
the membrane and requires the presence of so-called cystathionine
β-synthase (CBS) domains, suggesting that the ionic signal is transduced
to the transporter via critical interactions of the protein with membrane
lipids.The ABC transporter OpuA consists of two identical nucleotide-binding
domains (NBD) fused to CBS domains and two identical substrate-binding domains
fused to transmembrane domains. The NBD-CBS and substrate-binding
domain-transmembrane domain subunits are named OpuAA and OpuABC, respectively.
Two tandem CBS domains are linked to the C-terminal end of the NBD; each
domain (CBS1 and CBS2) has a β-α-β-β-α secondary
structure (5)
(Fig. 1A). The CBS
domains are widely distributed in most if not all species of life but their
function is largely unknown. Most of the CBS domains are found as tandem
repeats but data base searches have also revealed tetra-repeat units
(5). The crystal structures of
several tandem CBS domains have been elucidated
(7–9,
32), and in a number of cases
it has been shown that two tandem CBS domains form dimeric structures with a
total of four CBS domains per structural module (hereafter referred to as CBS
module). The crystal structures of the full-length MgtE Mg2+
transporter confirm the dimeric configuration and show that the CBS domains
undergo large conformational changes upon Mg2+ binding or release
(10,
11). In general, ABC
transporters are functional as dimers, which implies that two tandem CBS
domains are present in the OpuA complex. Preliminary experiments with
disulfides engineered at the interface of two tandem CBS domains in OpuA
suggest that large structural rearrangements (association-dissociation of the
interfaces) play a determining role in the ionic strength-regulated transport.
Finally, a subset of CBS-containing proteins has a C-terminal extension, which
in OpuA is highly anionic (sequence: ADIPDEDEVEEIEKEEENK) and modulates the
ion sensing activity (6).Open in a separate windowFIGURE 1.Domain structure of CBS module of OpuA. A, sequence of
tandem CBS domains. The predicted secondary structure is indicated
above the sequence. The residues modified in this study are
underlined. The amino acid sequence end-points of OpuAΔ61 and
OpuAΔ119 are indicated by vertical arrows. B, homology
model of tandem CBS domain of OpuA. The CBS domains were individually modeled
on the crystal structure of the tandem CBS protein Ta0289 from T.
acidophilum (PDB entry 1PVM), using Phyre. Ta0289 was used for the
initial modeling, because its primary sequence was more similar to the CBS
domains of OpuA than those of the other crystallized CBS proteins. The
individual domain models were then assembled with reference to the atomic
coordinates of the tandem CBS domains of IMPDH from Streptococcus
pyogenes (PDB entry 1ZFJ) to form the tandem CBS pair, using PyMOL
(DeLano). The positions of the (substituted) cationic residues are
indicated.In this study, we have engineered the surface-exposed cationic residues of
the CBS module and the C-terminal anionic tail of OpuA
(Fig. 1B). The ionic
strength and lipid dependence of the OpuA mutants were determined in
vivo and in vitro. We show that substitution of five cationic
residues for neutral amino acids is sufficient to inactivate the ionic
strength sensor and convert OpuA into a constitutively active transporter.
Moreover, by substituting six anionic plus four neutral residues of the
C-terminal anionic tail for histidines, the transport reaction becomes
strongly pH-dependent. 相似文献