Strong winds as driver of surf zooplankton abundance and composition in a temperate sandy beach.

This study explores the effect of different wind events (direction and duration) on the surf zone zooplankton community in a temperate sandy beach. Samplings were realized on the surf zone of Pehuen Co sandy beach during 17 wind events from May 17th, 2017, to July 19th, 2019. Biological samples were taken before and after the events. The identification of the events was realized using recorded high-frequency wind speed data. General Linear Model (LM) and Generalized linear models (GLM) were employed to compare physical and biological variables. We observed that the wind direction unequally altered the ecosystem along with its duration, modifying the composition and abundance of zooplankton communities. Short-duration wind events were associated with an increment in the zooplankton abundances, being Acartia tonsa and Paracalanus parvus dominant. Within the short-duration cases, winds from the W sector were identified with the inner continental shelf species' presence, such as Ctenocalanus vanus and Euterpina acutifrons, and to a lesser extent, Calanoides carinatus, and Labidocera fluviatilis, together with surf zone copepods. Long-duration cases were associated with a significant decrease in the zooplankton abundance. Within this group, SE-SW wind events were identified with adventitious fraction taxa. Considering that the occurrence of extreme events is growing because of climate change, affecting the frequency and intensity of storm surges, the knowledge of the responses of biological communities to these events is necessary. This work provides quantitative evidence on a short-time scale of the implications of the physical-biological interaction during different strong wind cases in surf zone waters of sandy beaches.

An overview on metal pollution on touristic sandy beaches: Is the COVID-19 pandemic an opportunity to improve coastal management?

The worldwide spread of the SARS-CoV-2 caused an unprecedented lockdown measures in most countries with consequences on the world society, economy, and sanitary systems. This situation provided an opportunity to identify the effects of human confinement on natural environments, like touristic sandy beaches, which are stressed due to anthropogenic pressures. Based on previous articles about heavy metals sources and levels in these ecosystems, this paper discusses the dynamic of these pollutants and a regulatory scenario associated with COVID-19 sanitation policies. The main findings suggest that 39% of the studies were on Asian sandy beaches, 16% from Europe, while America and Africa with 23% each. Also Co, Cd, Cu, Cr, Zn, Pb, Ni, Fe and Mn were the most frequently analyzed metals in sediments and in several cases their concentrations exceed international guidelines assessment. Finally, even though beaches are under several metals inputs, tourism plays a key role in these ecosystems quality. After analyzing the potential indirect effect of COVID-19 measures on metals dynamics, we propose some key recommendations and management strategies to mitigate heavy metal pollution on sandy tourist beaches. These proposals are useful for decision-makers and stakeholders to improve sandy beach management, mainly those beaches not addressed from a management perspective; and their implementation should be adapted according to the regulations and legislation of each country.

Characterization of an rRNA operon (rrnB) of Mycobacterium fortuitum and other mycobacterial species: implications for the classification of mycobacteria.

Mycobacteria are thought to have either one or two rRNA operons per genome. All mycobacteria investigated to date have an operon, designated rrnA, located downstream from the murA gene. We report that Mycobacteriun fortuitum has a second rrn operon, designated rrnB, which is located downstream from the tyrS gene; tyrS is very close to the 3' end of a gene (3-mag) coding for 3-methylpurine-DNA-glycosylase. The second rrn operon of Mycobacterium smegmatis was shown to have a similar organization, namely, 5' 3-mag-tyrS-rrnB 3'. The rrnB operon of M. fortuitum was found to have a single dedicated promoter. During exponential growth in a rich medium, the rrnB and rrnA operons were the major and minor contributors, respectively, to pre-rRNA synthesis. Genomic DNA was isolated from eight other fast-growing mycobacterial species. Samples were investigated by Southern blot analysis using probes for murA, tyrS, and 16S rRNA sequences. The results revealed that both rrnA and rrnB operons were present in each species. The results form the basis for a proposed new scheme for the classification of mycobacteria. The approach, which is phylogenetic in concept, is based on particular properties of the rrn operons of a cell, namely, the number per genome and a feature of 16S rRNA gene sequences.

Characterization of a Mycobacterium intracellulare variant strain by molecular techniques.

This paper describes a Mycobacterium intracellulare variant strain causing an unusual infection. Several isolates obtained from an immunocompromised patient were identified as members of the Mycobacterium avium complex (MAC) by the commercial AccuProbe system and biochemical standard identification. Further molecular approaches were undertaken for a more accurate characterization of the bacteria. Up to seven different genomic sequences were analyzed, ranging from conserved mycobacterial genes such as 16S ribosomal DNA to MAC-specific genes such as mig (macrophage-induced gene). The results obtained identify the isolates as a variant of M. intracellulare, an example of the internal variability described for members of the MAC, particularly within that species. The application of other molecular approaches is recommended for more accurate identification of bacteria described as MAC members.

Mycobacterium wolinskyi sp. nov. and Mycobacterium goodii sp. nov., two new rapidly growing species related to Mycobacterium smegmatis and associated with human wound infections: a cooperative study from the International Working Group on Mycobacterial Taxonomy.

Previous investigations demonstrated three taxonomic groups among 22 clinical isolates of Mycobacterium smegmatis. These studies were expanded to 71 clinical isolates, of which 35 (49%) (group 1) were identical to five ATCC reference strains including the type strain ATCC 19420T. Twenty-eight isolates (39%) were group 2, and eight isolates (11%) were group 3. Isolates of groups 2 and 3 were most often associated with post-traumatic or post-surgical wound infections including osteomyelitis, were susceptible to sulfamethoxazole, amikacin, imipenem and the tetracyclines, variably resistant to clarithromycin, and susceptible (group 1), intermediately resistant (group 2) or resistant (group 3) to tobramycin. The three groups were similar by routine biochemical and growth characteristics, but had different mycolic acid dimethoxy-4-coumarinylmethyl ester elution patterns by HPLC and different PCR-restriction enzyme patterns of a 439 bp fragment of the hsp-65 gene. Group 3 isolates differed from group 1 by 18 bp by 16S rRNA sequencing and exhibited < 25% homology by DNA-DNA hybridization, being most closely related to Mycobacterium mageritense. The 16S rRNA of group 1 and group 2 isolates differed by only 3 bp, but by DNA-DNA hybridization they exhibited only 40% homology. The following names are proposed: Mycobacterium goodii sp. nov. for group 2 isolates (type strain ATCC 700504T = MO69T), Mycobacterium wolinskyi sp. nov. for group 3 isolates (type strain ATCC 700010T = MO739T) and Mycobacterium smegmatis sensu stricto for group 1 isolates.

katGI and katGII encode two different catalases-peroxidases in Mycobacterium fortuitum.

It has been suggested that catalase-peroxidase plays an important role in several aspects of mycobacterial metabolism and is a virulence factor in the main pathogenic mycobacteria. In this investigation, we studied genes encoding for this protein in the fast-growing opportunistic pathogen Mycobacterium fortuitum. Nucleotide sequences of two different catalase-peroxidase genes (katGI and katGII) of M. fortuitum are described. They show only 64% homology at the nucleotide level and 55% identity at the amino acid level, and they are more similar to catalases-peroxidases from different bacteria, including mycobacteria, than to each other. Both proteins were found to be expressed in actively growing M. fortuitum, and both could also be expressed when transformed into Escherichia coli and M. aurum. We detected the presence of a copy of IS6100 in the neighboring region of a katG gene in the M. fortuitum strain in which this element was identified (strain FC1). The influence of each katG gene on isoniazid (isonicotinic acid hydrazide; INH) susceptibility of mycobacteria was checked by using the INH-sensitive M. aurum as the host. Resistance to INH was induced when katGI was transformed into INH-sensitive M. aurum, suggesting that this enzyme contributes to the natural resistance of M. fortuitum to the drug. This is the first report showing two different genes encoding same enzyme activity which are actively expressed within the same mycobacterial strain.

Mycobacterium mageritense sp. nov.

Strains of a new species of rapidly growing, nonphotochromogenic mycobacteria, Mycobacterium mageritense, were isolated from human sputum. The growth characteristics, acid fastness, and mycolic acids of the isolates were consistent with those of Mycobacterium species. The isolates were identified as members of a new species by performing a biochemical analysis and DNA-DNA hybridization experiments, and by comparing the sequences of several conserved genes, such as the 16S rRNA, hsp65, and sodA genes. A phylogenetic analysis in which 16S rRNA and sodA sequences were used identified M. mageritense as a novel distinct species and placed M. mageritense between members of the Mycobacterium fortuitum complex and the thermotolerant rapidly growing group. Our results demonstrate that the taxonomic value of sodA sequence analysis in the genus Mycobacterium is similar to the well-established value of 16S rRNA sequence analysis.

Cloning and expression of the Mycobacterium fortuitum superoxide dismutase gene.

In this paper we report the cloning, sequencing and expression of the superoxide dismutase (sod) gene from Mycobacterium fortuitum. A single gene was found to code for superoxide dismutase activity with its identity being confirmed by expression in M. aurum. The amino acid sequence was found to be similar to that of superoxide dismutases of several other origins. A region downstream of the sod gene also showed similarities to the corresponding sequences of the two main mycobacterial pathogens: M. leprae and M. tuberculosis. Analysis of enzymatic activity showed this enzyme in M. fortuitum required manganese as cofactor.

Insertion sequence IS1137, a new IS3 family element from Mycobacterium smegmatis.

A new insertion sequence (IS) has been isolated from Mycobacterium smegmatis. It is 1361 bp long and possesses characteristics of the IS3 family elements. It harbours 32 bp imperfect inverted repeats at its extremities and a 3 bp direct repeat flanks the element, possibly as the result of a transposition event. This IS, IS1137, contains three major ORFs. Two of them, ORF A and ORF B show homologies both at the amino acid sequence level and at the organization level with the ORFs encoding the transposase of the IS3 family elements. IS1137 has a narrow host range and was found only in M. smegmatis and M. chitae. The fact that IS1137 is not present in the M. tuberculosis complex strains makes this element a new candidate for transposon mutagenesis in mycobacteria.

Restriction fragment length polymorphisms of 16S rRNA genes in the differentiation of fast-growing mycobacterial species.

DNA from several species of fast growing mycobacteria displayed a characteristic restriction fragment length polymorphism (RFLP) pattern when hybridizated to a Mycobacterium fortuitum 16S rRNA gene fragment. The resulting patterns were identical when comparing different strains belonging to the same species. The RFLP results were consistent with those obtained by DNA-DNA hybridization studies. Using this approach, we have been able to identify the number of copies for 16S rRNA genes in several fast-growing mycobacteria.

Brugia species in a man from western Ethiopia.

A case of human brugiasis in a student from Gambela, Ethiopia, is reported. Ten sheathed microfilariae showing the Brugia genus characteristics were recovered from 1 ml of blood.