In the shadow of the Moon,what type of solar eclipse will we see?

Solar eclipses occur several times a year, but most people will be lucky if they see one total solar eclipse in their lifetime. There are two upcoming total solar eclipses that can be seen from different parts of the United States (August 21, 2017 and April 8, 2024), and they provide teachers with an amazing opportunity to engage students with a remarkable astronomical event. We summarize the science behind eclipses and describe an inexpensive activity for students from third grade up through middle school that will let them use models to see the differences between total, annular, and partial solar eclipses. The activity lets students explore why, during a solar eclipse, people in different areas will see different types of eclipses. The activity can be used as a way to get students excited about astronomy and the upcoming eclipses. We also give ideas for ways that teachers can engage their students during the eclipses.     

Variability of the Basal Esophageal Sheath in Belondirid Nematodes

The structure of the basal esophageal sheath was studied in Axonchium amplicolle, A. choristurn, A. crassum, A. gigas, A. micans, A. rotundum, A. serpens, A. solitare, Dorylairnellus aequalis, D. parvulus, D. tenuidens, Oxydirus gangeticus, O. gigus, O. oxycephaloides, and Swangeria bisexualis. In A. gigas the muscle bands comprising the sheath spiral dextrally, but in the other species of Axonchiurn they do not spiral but lie parallel to the esophagus. In O. gigus the spiral is sinistral, whereas in the other two species of Oxydirus it is dextral. The spiral is very slight in Dorylairnellus aequalis, each band passing around only about 180 degrees of the circumference of the esophagus. They completely encircle the esophagus in D. parvulus, and pass around about 3/4 the circumference in D. tenuidens. The definitions of Belondiroidea Thorne, 1964 and of Axonchium Cobb, 1920 are emended to recognize the variability in the structure of the sheath.     

Social aggregation of adult Schistocerca gregaria and Locusta migratoria migratorioides in relation to the final moult and ageing

Laboratory experiments, were carried out on nymphs and adults of the desert locust, Schistocerca gregaria, and the African migratory locust, Locusta migratoria migratorioides, in view of the field observation that locusts become temporarily less gregarious after the final moult. The experiments showed no reduction in grouping after the final moult but did show a reduction in grouping in mature Schistocerca. There was little change in the numbers of locusts found in small groups but a dramatic reduction in the number found in large groups.     

An overview on the recently discovered iota-carbonic anhydrases

Carbonic anhydrases (CAs, EC 4.2.1.1) have been studied for decades and have been classified as a superfamily of enzymes which includes, up to date, eight gene families or classes indicated with the Greek letters α, β, γ, δ, ζ, η, θ, ι. This versatile enzyme superfamily is involved in multiple physiological processes, catalysing a fundamental reaction for all living organisms, the reversible hydration of carbon dioxide to bicarbonate and a proton. Recently, the ι-CA (LCIP63) from the diatom Thalassiosira pseudonana and a bacterial ι-CA (BteCAι) identified in the genome of Burkholderia territorii were characterised. The recombinant BteCAι was observed to act as an excellent catalyst for the physiologic reaction. Very recently, the discovery of a novel ι-CAs (COG4337) in the eukaryotic microalga Bigelowiella natans and the cyanobacterium Anabaena sp. PCC7120 has brought to light an unexpected feature for this ancient superfamily: this ι-CAs was catalytically active without a metal ion cofactor, unlike the previous reported ι-CAs as well as all known CAs investigated so far. This review reports recent investigations on ι-CAs obtained in these last three years, highlighting their peculiar features, and hypothesising that possibly this new CA family shows catalytic activity without the need of metal ions.     

Characterization of the Gut Microbiota of Papua New Guineans Using Reverse Transcription Quantitative PCR

There has been considerable interest in composition of gut microbiota in recent years, leading to a better understanding of the role the gut microbiota plays in health and disease. Most studies have been limited in their geographical and socioeconomic diversity to high-income settings, and have been conducted using small sample sizes. To date, few analyses have been conducted in low-income settings, where a better understanding of the gut microbiome could lead to the greatest return in terms of health benefits. Here, we have used quantitative real-time polymerase chain reaction targeting dominant and sub-dominant groups of microorganisms associated with human gut microbiome in 115 people living a subsistence lifestyle in rural areas of Papua New Guinea. Quantification of Clostridium coccoides group, C. leptum subgroup, C. perfringens, Bacteroides fragilis group, Bifidobacterium, Atopobium cluster, Prevotella, Enterobacteriaceae, Enterococcus, Staphylococcus, and Lactobacillus spp. was conducted. Principle coordinates analysis (PCoA) revealed two dimensions with Prevotella, clostridia, Atopobium, Enterobacteriaceae, Enterococcus and Staphylococcus grouping in one dimension, while B. fragilis, Bifidobacterium and Lactobacillus grouping in the second dimension. Highland people had higher numbers of most groups of bacteria detected, and this is likely a key factor for the differences revealed by PCoA between highland and lowland study participants. Age and sex were not major determinants in microbial population composition. The study demonstrates a gut microbial composition with some similarities to those observed in other low-income settings where traditional diets are consumed, which have previously been suggested to favor energy extraction from a carbohydrate rich diet.     

Insights from paleomicrobiology into the indigenous peoples of pre-colonial America - A Review

This review investigates ancient infectious diseases in the Americas dated to the pre-colonial period and considers what these findings can tell us about the history of the indigenous peoples of the Americas. It gives an overview, but focuses on four microbial pathogens from this period: Helicobacter pylori, Mycobacterium tuberculosis, Trypanosoma cruzi and Coccidioides immitis, which cause stomach ulceration and gastric cancer, tuberculosis, Chagas disease and valley fever, respectively. These pathogens were selected as H. pylori can give insight into ancient human migrations into the Americas, M. tuberculosis is associated with population density and urban development, T. cruzi can elucidate human living conditions and C. immitis can indicate agricultural development. A range of methods are used to diagnose infectious disease in ancient human remains, with DNA analysis by polymerase chain reaction one of the most reliable, provided strict precautions are taken against cross contamination. The review concludes with a brief summary of the changes that took place after European exploration and colonisation.     

Ancient DNA and the tropics: a rodent's tale

Most genetic studies of Holocene fauna have been performed with ancient samples from dry and cold regions, in which preservation of fossils is facilitated and molecular damage is reduced. Ancient DNA work from tropical regions has been precluded owing to factors that limit DNA preservation (e.g. temperature, hydrolytic damage). We analysed ancient DNA from rodent jawbones identified as Ototylomys phyllotis, found in Holocene and Late Pleistocene stratigraphic layers from Loltún, a humid tropical cave located in the Yucatan peninsula. We extracted DNA and amplified six short overlapping fragments of the cytochrome b gene, totalling 666 bp, which represents an unprecedented success considering tropical ancient DNA samples. We performed genetic, phylogenetic and divergence time analyses, combining sequences from ancient and modern O. phyllotis, in order to assess the ancestry of the Loltún samples. Results show that all ancient samples fall into a unique clade that diverged prior to the divergence of the modern O. phyllotis, supporting it as a distinct Pleistocene form of the Ototylomys genus. Hence, this rodent''s tale suggests that the sister group to modern O. phyllotis arose during the Miocene–Pliocene, diversified during the Pleistocene and went extinct in the Holocene.     

Fate of transforming DNA following uptake by competent Bacillus subtilis. I. Formation and properties of the donor-recipient complex

Following uptake by competent Bacillus subtilis, transforming DNA is converted to two distinct slowly sedimenting molecular forms which possess little transforming activity (eclipse). A few minutes after uptake is initiated, a physical complex of donor and recipient DNA begins to form. The recovery of donor transforming activity following eclipse, and the appearance of recombinant activity, previously reported by Venema, Pritchard &; Venema-Schröder (1965), is shown to be due to changes occurring in the donor—recipient complex. This complex exists transiently in a form with low recombinant-type transforming activity. This transient form may be one in which the donor and recipient components are joined non-covalently. The donor-recipient complex is shown to be a heteroduplex structure in which the donor moiety has an approximate molecular weight of 750,000.     

Eclipse period during replication of plasmid R1: contributions from structural events and from the copy-number control system

The eclipse period (the time period during which a newly replicated plasmid copy is not available for a new replication) of plasmid R1 in Escherichia coli was determined with the classic Meselson-Stahl density-shift experiment. A mini-plasmid with the wild-type R1 replicon and a mutant with a thermo-inducible runaway-replication phenotype were used in this work. The eclipses of the chromosome and of the wild-type plasmid were 0.6 and 0.2 generation times, respectively, at temperatures ranging from 30 degrees C to 42 degrees C. The mutant plasmid had a similar eclipse at temperatures up to 38 degrees C. At 42 degrees C, the plasmid copy number increased rapidly because of the absence of replication control and replication reached a rate of 350-400 plasmid replications per cell and cell generation. During uncontrolled replication, the eclipse was about 3 min compared with 10 min at controlled replication (the wild-type plasmid at 42 degrees C). Hence, the copy-number control system contributed significantly to the eclipse. The eclipse in the absence of copy-number control (3 min) presumably is caused by structural requirements: the covalently closed circular plasmid DNA has to regain the right degree of superhelicity needed for initiation of replication and it takes time to assemble the initiation factors.     

Molecular Characterization of Primary Gene Pool of Chickpea Based on ISSR Markers

Genetic diversity and relationships within and among members of the primary gene pool of chickpea, including 38 accessions of Cicer arietinum, six of C. reticulatum,, and four of C. echinospermum, were investigated using 31 ISSR markers. The study revealed moderate diversity, detecting 141 fragments, of which 79 (56%) were polymorphic. Averages were 0.125 for polymorphic information content, 0.350 for marker index, and 0.715 for resolving power. The UPGMA dendrogram and the principal coordinate analysis revealed a clear differentiation between wild and cultivated accessions. The clustering pattern did not strictly follow the grouping of accessions by geographic origin but was in good agreement with the pedigree data and the seed type. The study demonstrates that ISSRs provide promising marker tools in revealing genetic diversity and relationships in chickpea and can contribute to efficient identification, conservation, and utilization of germplasm for plant improvement through conventional as well as molecular breeding approaches.     

Characterization of Heterorhabditis Isolates by PCR Amplification of Segments of mtDNA and rDNA Genes

Restriction digests of amplified DNA from the mitochondrial genome and the nuclear ribosomal internally transcribed spacer region have been evaluated as genetic markers for species groups in Heterorhabditis. Six RFLP profiles have been identified. These profiles supported groupings determined by cross-breeding studies and were in agreement with less definitive groupings based on other biochemical and molecular methods. Digestion patterns of both amplification products provided strong evidence for the recognition of species groups, which include Irish, NW European, tropical, and a H. bacteriophora complex. The H. bacteriophora complex could be further resolved into three genotypes represented by H. zealandica, the H. bacteriophora, Brecon (Australian) type isolate for H. bacteriophora, and a grouping composed of isolates NC1, V16, HI82, and HP88. All cultures obtained of the H. megidis isolate were identical to the NW European group. These results could be used to aid monitoring of field release of Heterorhabditis as well as allowing a rapid initial assessment of taxonomic grouping.     

Molecular Identification of Bacteria by Total Sequence Screening: Determining the Cause of Death in Ancient Human Subjects

Research of ancient pathogens in ancient human skeletons has been mainly carried out on the basis of one essential historical or archaeological observation, permitting specific pathogens to be targeted. Detection of ancient human pathogens without such evidence is more difficult, since the quantity and quality of ancient DNA, as well as the environmental bacteria potentially present in the sample, limit the analyses possible. Using human lung tissue and/or teeth samples from burials in eastern Siberia, dating from the end of 17^th to the 19^th century, we propose a methodology that includes the: 1) amplification of all 16S rDNA gene sequences present in each sample; 2) identification of all bacterial DNA sequences with a degree of identity ≥95%, according to quality criteria; 3) identification and confirmation of bacterial pathogens by the amplification of the rpoB gene; and 4) establishment of authenticity criteria for ancient DNA. This study demonstrates that from teeth samples originating from ancient human subjects, we can realise: 1) the correct identification of bacterial molecular sequence signatures by quality criteria; 2) the separation of environmental and pathogenic bacterial 16S rDNA sequences; 3) the distribution of bacterial species for each subject and for each burial; and 4) the characterisation of bacteria specific to the permafrost. Moreover, we identified three pathogens in different teeth samples by 16S rDNA sequence amplification: Bordetella sp., Streptococcus pneumoniae and Shigella dysenteriae. We tested for the presence of these pathogens by amplifying the rpoB gene. For the first time, we confirmed sequences from Bordetella pertussis in the lungs of an ancient male Siberian subject, whose grave dated from the end of the 17^th century to the early 18^th century.     

Formyltetrahydrofolate Synthetase Sequences from Salt Marsh Plant Roots Reveal a Diversity of Acetogenic Bacteria and Other Bacterial Functional Groups

Sixty-two partial formyltetrahydrofolate synthetase (FTHFS) structural gene sequences were recovered from roots of salt marsh plants, including Spartina alterniflora, Salicornia virginica, and Juncus roemerianus. Only S. alterniflora roots yielded sequences grouping with FTHFS sequences from known acetogens. Most other FTHFS or FTHFS-like sequences grouped with those from sulfate-reducing bacteria. Several sequences that grouped with Sphingomonas paucimobilis ligH were also recovered.     

Effect of a total solar eclipse on the surface crowding of zooplankton in a freshwater lake ecosystem

Zooplankton surface crowding in a freshwater lake ecosystem during a total solar eclipse (maximum eclipse at 06:28:43 Indian Standard Time, 22 July 2009) was studied in relation to ambient physicochemical conditions and compared with the crowding that occurred during pre- and post-eclipse days. Rapid light attenuation on the eclipse day led to changes in zooplankton surface crowding, which manifested as alterations to community structure and statistical parameters. Zooplankton diversity and density varied depending on the day (either the pre-eclipse day, the eclipse day, or the post-eclipse day) and the sampling time considered. A total of 20 zooplankton species were recorded during the study. On the day of the eclipse, the highest zooplankton density in the surface water was recorded just after the end of totality at 06:30 IST. The populations of two adult cladoceran species (Alona rectangula rectangula and Chydorus sphaericus) were particularly prominent in the zooplankton, whereas rotifers were almost absent from the surface water during the eclipse. Rather than decreasing, the primary production of the phytoplankton increased on the day of the TSE compared to that seen on the control days. Comparatively high Lindeman’s efficiency values were observed during the eclipse, indicating particularly efficient utilization of photons in photosynthesis.     

The effect of ultraviolet light on the production of bacterial virus protein

The amount of phage-specific protein in T2-infected bacteria growing in a medium containing radiosulfur, S³⁵, has been studied by measuring the radioactivity in specific antiphage serum precipitates of lysates. In the course of normal infection, non-infective phage antigen has been found to make its first intracellular appearance shortly before the end of the eclipse period, in agreement with the findings of Maaløe and Symonds with phage T4. No such phage antigen is produced either in bacteria infected with UV-inactivated T2 or in T2-infected bacteria whose survival as an infective center has been destroyed by UV irradiation during the early stages of the eclipse period. If the infected bacteria are UV-irradiated only at later stages of the eclipse period however, then phage antigenic protein continues to be synthesized in those infected cells in which DNA synthesis and, a fortiori, production of infective progeny have been almost completely suppressed. It is concluded from these results that once the mechanism for formation of phage-specific protein has been established within the infected cell under the influence of the parental DNA, synthesis of phage-specific protein can continue independently of the synthesis of phage DNA. The possibility that the phage DNA controls the specificity of the phage protein indirectly through substances other than DNA is discussed.     

Diversity of symbiotic microbiota in Deltocephalinae leafhoppers (Insecta,Hemiptera, Cicadellidae)

Symbiotic microorganisms associated with thirteen species of the subfamily Deltocephalinae were examined using microscopic and molecular techniques. Athysanus argentarius, Euscelis incisus, Doratura stylata, Arthaldeus pascuellus, Errastunus ocellaris, Jassargus flori, Jassargus pseudocellaris, Psammotettix alienus, Psammotettix confinis, Turrutus socialis and Verdanus abdominalis harbor two types of ancient bacteriome-associated microorganisms: bacteria Sulcia (phylum Bacteroidetes) and bacteria Nasuia (phylum Proteobacteria, class Betaproteobacteria). In Balclutha calamagrostis and Balclutha punctata, the bacterium Nasuia has not been detected. In the bacteriomes of both species of Balclutha examined, only bacteria Sulcia occur, whereas Sodalis-like symbionts (phylum Proteobacteria, class Gammaproteobacteria) are localized in the fat body cells, in close vicinity of the bacteriomes. To our knowledge, this is the first report of the co-existence in Deltocephalinae leafhoppers of the ancient symbiont Sulcia and the more recently acquired Sodalis-like bacterium. The obtained results provide further evidence indicating that Deltocephalinae leafhoppers are characterized by a large diversity of symbiotic systems, which results from symbiont acquisition and replacement. The obtained results are additionally discussed in phylogenetic context.     

Function and structure of microvirid phage α3 genome. DNA sequence of H gene and properties of missense H mutant

The nucleotide sequence of wild-type α3 H gene and its surrounding region was determined and compared with those of ?X174 and G4. The corresponding DNA regions in double mutants amJH22, amJH69 and amJH76 were also sequenced and their missense mutation sites located. A phage strain missH22 having a single missense mutation in gene H was constructed by replacing the J region of amJH22 in vitro with the wild-type DNA. Like amJH22, the missense mutant coded for H protein with aberrant electrophoretic mobility, but formed normal plaques on suppressor-deficient Escherichia coli. Heat stability, plating efficiency on certain hosts and rate of eclipse were higher in strain missH22 than in wild-type phage.     

Measurements of transmembrane potential and magnetic field at the apex of the heart

We studied the transmembrane potential and magnetic fields from electrical activity at the apex of the isolated rabbit heart experimentally using optical mapping and superconducting quantum interference device microscopy, and theoretically using monodomain and bidomain models. The cardiac apex has a complex spiral fiber architecture that plays an important role in the development and propagation of action currents during stimulation at the apex. This spiral fiber orientation contains both radial electric currents that contribute to the electrocardiogram and electrically silent circular currents that cannot be detected by the electrocardiogram but are detectable by their magnetic field, B_z. In our experiments, the transmembrane potential, V_m, was first measured optically and then B_z was measured with a superconducting quantum interference device microscope. Based on a simple model of the spiral structure of the apex, V_m was expected to exhibit circular wave front patterns and B_z to reflect the circular component of the action currents. Although the circular V_m wave fronts were detected, the B_z maps were not as simple as expected. However, we observed a pattern consistent with a tilted axis for the apex spiral fiber geometry. We were able to simulate similar patterns in both a monodomain model of a tilted stack of rings of dipole current and a bidomain model of a tilted stack of spiraled cardiac tissue that was stimulated at the apex. The fact that the spatial pattern of the magnetic data was more complex than the simple circles observed for V_m suggests that the magnetic data contain information that cannot be found electrically.     

Isolation of brush border membranes in vesicular form from the intestinal spiral valve of the small dogfish (Scyliorhinus canicula)

A simple, rapid method for the preparation of purified brush border membranes in vesicular form from rabbit kidney proximal tubules has been applied with closely similar results to the intestinal spiral valve of the small dogfish (Scyliorhinus canicula). Since the dogfish belongs to one of the most ancient species of fish, it may be suggested that the method is generally applicable to all species later evolved which possess a brush border membrane at the mucosal surface of the cells of the intestine or kidney.