Binary Fission Research Articles

¡vIVA la DivIVA!

Reproduction in the bacterial kingdom predominantly occurs through binary fission-a process in which one parental cell is divided into two similarly sized daughter cells. How cell division, in conjunction with cell elongation and chromosome segregation, is orchestrated by a multitude of proteins has been an active area of research spanning the past few decades. Together, the monumental endeavors of multiple laboratories have identified several cell division and cell shape regulators as well as their underlying regulatory mechanisms in rod-shaped Escherichia coli and Bacillus subtilis, which serve as model organisms for Gram-negative and Gram-positive bacteria, respectively. Yet our understanding of bacterial cell division and morphology regulation is far from complete, especially in noncanonical and non-rod-shaped organisms. In this review, we focus on two proteins that are highly conserved in Gram-positive organisms, DivIVA and its homolog GpsB, and attempt to summarize the recent advances in this area of research and discuss their various roles in cell division, cell growth, and chromosome segregation in addition to their interactome and posttranslational regulation.

Nanoscale imaging of E. coli cells by expansion microscopy.

Expansion microscopy (ExM) is an emerging super-resolution imaging technology. ExM works by infusing a biological specimen with a superabsorbent hydrogel, followed by mechanical homogenization and isotropical expansion of the specimen in water. The unique and cost-effective process of ExM enables super-resolution optical imaging of sample of interest without the need to invest and use of a sophisticated microscope instrument. Here, we demonstrate that a nearly 3-fold isotropic physical expansion of E.coli fixed cells can be achieved in PBS, and the cell morphology during binary fission is clearly resolved in the expanded state, using a diffraction-limited microscope.

Congenital anomalies from a physics perspective. The key role of “manufacturing” volatility

Genetic and environmental factors are traditionally seen as the sole causes of congenital anomalies. In this paper we introduce a third possible cause, namely random “manufacturing” discrepancies with respect to “design” values. A clear way to demonstrate the existence of this component is to “turn off” the two others and to see whether or not there is still remaining variability. Perfect clones raised under well controlled laboratory conditions fulfill the conditions for such a test. Carried out for four different species, the test reveals a variability remainder of the order of 15% in terms of coefficient of variation (i.e. ratio of standard deviation to average, subsequently denoted by CV). As an example, the CV of the volume of E. coli (Escherichia Coli) bacteria immediately after binary fission is of that order.In short, “manufacturing” discrepancies occur randomly, even when no harmful mutation or environmental factors are involved. If the pathway is particularly long or requires exceptional accuracy, output dispersion will be high and may lead to malformations. This effect will be referred to as the random dispersion effect. We conjecture that it will be particularly significant when major changes occur; this includes the early phase of embryogenesis or the first steps leading from stem cells to differentiated (organ-specific) cells.The dispersion effect not only causes malformations but also innocuous variability. For instance monozygotic (MZ) twins resemble each other but are not strictly identical. It is not uncommon to see only one of the twins of a MZ pair showing a congenital defect (see Appendix A).Not surprisingly, there is a strong connection between congenital defects and infant mortality. In the wake of birth there is a gradual elimination of defective units and this screening accounts for the decline of postnatal infant mortality. In humans, for reasons which are not yet understood, this decline continues until the age of about 10 years. Neither do we understand why, as a function of age, the downward trend of human infant mortality follows a power law with an exponent around 1 (whereas for fish it is about 3, see Bois et al. 2019a). Apart from this trend, post-natal death rates also have humps and peaks associated with various inabilities and defects.In short, infant mortality rates convert the case-by-case and mostly qualitative problem of congenital malformations into a global quantitative effect which, so to say, summarizes what goes wrong in the embryonic phase.Based on the natural assumption that for simple organisms (e.g. rotifers) the manufacturing processes are shorter than for more complex organisms (e.g. mammals), fewer congenital anomalies are expected and therefore also lower infant mortality. How this conjecture can be tested is outlined in our conclusion.

Comparing the Parameters of T-odd Asymmetries in Cross Sections of the Ternary Fission of Nuclei by Cold Polarized Neutrons with the Emission of Pre-Scission and Evaporation Third Particles

A comparison is made of two theoretical approaches to describing the coefficients of T-odd asymmetries in the angular distributions of prompt γ-quanta and neutrons evaporated from thermalized fragments of the binary fission of non-oriented target nuclei by cold polarized neutrons, and in angular distributions of pre-scission α particles emitted in the same ternary nuclear fission: the classical approach, which is based on trajectory calculations, and the quantum approach, which is based on quantum fission theory. It is shown that the coefficients for all of the considered nuclei are of a quantum nature and vanish in the classical approach when there is no interference from the fission amplitudes of the different neutron resonances of a compound nucleus. The advantages of the quantum approach versus the classical one are demonstrated.

Competition between binary fission, ternary fission, cluster radioactivity and alpha decay of 281Ds

The competition between different decay modes such as binary fission, ternary fission, cluster and alpha decay modes finds an important role in the synthesis of superheavy nuclei. The nuclei 281Ds is the most stable among the isotopes of Ds. We have studied the different decay modes in superheavy nuclei 281Ds. It is observed that alpha decay half-lives are smaller compared to other modes. The alpha decay mode of 281Ds is observed with greater probability compared to binary fission.

The speciation and hybridization history of the genus Salmonella

Bacteria and archaea make up most of natural diversity, but the mechanisms that underlie the origin and maintenance of prokaryotic species are poorly understood. We investigated the speciation history of the genus Salmonella , an ecologically diverse bacterial lineage, within which S. enterica subsp. enterica is responsible for important human food-borne infections. We performed a survey of diversity across a large reference collection using multilocus sequence typing, followed by genome sequencing of distinct lineages. We identified 11 distinct phylogroups, 3 of which were previously undescribed. Strains assigned to S. enterica subsp. salamae are polyphyletic, with two distinct lineages that we designate Salamae A and B. Strains of the subspecies houtenae are subdivided into two groups, Houtenae A and B, and are both related to Selander’s group VII. A phylogroup we designate VIII was previously unknown. A simple binary fission model of speciation cannot explain observed patterns of sequence diversity. In the recent past, there have been large-scale hybridization events involving an unsampled ancestral lineage and three distantly related lineages of the genus that have given rise to Houtenae A, Houtenae B and VII. We found no evidence for ongoing hybridization in the other eight lineages, but detected subtler signals of ancient recombination events. We are unable to fully resolve the speciation history of the genus, which might have involved additional speciation-by-hybridization or multi-way speciation events. Our results imply that traditional models of speciation by binary fission and divergence are not sufficient to account for Salmonella evolution.

Growth and the cell cycle in green algae dividing by multiple fission.

Most cells divide into two daughter cells; however, some green algae can have different division patterns in which a single mother cell can sometimes give rise to up to thousands of daughter cells. Although such cell cycle patterns can be very complex, they are governed by the same general concepts as the most common binary fission. Moreover, cell cycle progression appears to be connected with size, since cells need to ensure that their size after division will not drop below the limit required for survival. Although the exact mechanism that lets cells measure cell size remains largely unknown, there have been several prominent hypotheses that try to explain it.

Hindgut Ciliate Composition of Thoroughbred Mares in Kentucky, USA, and Binary Fission in Polymorphella ampulla.

Species composition and distribution of hindgut ciliates were investigated in the feces of 20 thoroughbred mares in Kentucky, USA. Thirty-three species and six morphotypes belonging to 21 genera were identified. The average density of hindgut ciliates in mares was 13.5 ± 13.7 × 104 cells ml-1, whereas mean number of ciliate species per host was 14.4 ± 5.3. Bundleia nana, B. elongata, B. piriformis, Blepharoconus hemiciliatus, Holophryoides ovalis, H. macrotricha, Blepharoprosthium polytrichum, Prorodonopsis coli, Paraisotrichopsis composita, Blepharocorys microcorys, and Ochoterenaia appendiculata were the first identified species in horses inhabited in USA. Scanning electron microscopic images of Holophryoides macrotricha, Paraisotrichopsis composita, Cycloposthium dentiferum m. corrugatum, C. edentatum m. edentatum, C. edentatum m. scutigerum, Tetratoxum parvum m. parvum, T. parvum m. sulcatum, T. excavatum m. excavatum, Allantosoma intestinale, and Arcosoma brevicorniger were studied. Binary fission in Polymorphella ampulla was also studied.

Juxtaposed membranes underpin cellular adhesion and display unilateral cell division of multicellular magnetotactic prokaryotes.

Multicellular magnetotactic prokaryotes (MMPs) exhibit peculiar coordination of swimming along geomagnetic field lines. Approximately 40-80 cells assemble, with a helical geometry or axisymmetry, into spherical or ellipsoidal MMPs respectively. To contribute to a comprehensive understanding of bacterial multicellularity here we took multiple microscopic approaches to study the diversity, assembly, reproduction and motility of ellipsoidal MMPs. Using correlative fluorescence in situ hybridization and scanning electron microscopy analysis, we found an unexpected diversity in populations of ellipsoidal MMPs in the Mediterranean Sea. The high-pressure freezing/freeze substitution fixation technique allowed us to show, for the first time, that cells adhere via juxtaposed membranes and are held together by a rimming lattice. Fluorescence confocal microscopy and ultrathin section images revealed not only the one-layer hollow three-dimensional architecture, but also periphery-core unilateral constriction of constituent cells and unidirectional binary fission of the ellipsoidal MMPs. This finding suggests the evolution toward MMPs multicellularity via the mechanism of incomplete separation of offspring. Remarkably, thousands of flagellar at the periphery surface of cells underpin the coordinated swimming of MMPs in response to mechanical, chemical, magnetic and optical stimuli, including a magnetotactic photokinesis behaviour. Together these results unveil the unique structure and function property of ellipsoidal MMPs.

At the Heart of Bacterial Cytokinesis: The Z Ring.

Bacterial cell division is mediated by the divisome which is organized by the Z ring, a cytoskeletal element formed by the polymerization of the tubulin homologue FtsZ. Despite billions of years of bacterial evolution, the Z ring is nearly universal among bacteria that have a cell wall and divide by binary fission. Recent studies have revealed the mechanism of cooperative assembly of FtsZ and that the Z ring consists of patches of FtsZ filaments tethered to the membrane that treadmill to distribute the septal biosynthetic machinery. Here, we summarize these advances and discuss questions raised by these new findings.

Pattern of cell division in ∼3.4 Ga-old microbes from South Africa

In cell division, most microbes rely on binary fission. Some, however, show less common division patterns, such as multiple fission or budding. Little is known about the nature of cell division in the Earth’s earliest fossil microbes, largely because of their poor preservation, but such details could be key in establishing the biogenicity of putative Archean fossils and their relationships to modern microbes. In this report we describe cellularly preserved microfossils from Paleoarchean (∼3.4-Ga-old) deposits of South Africa (Kromberg Formation). Their cellularity is revealed by well-preserved reproduction patterns exemplified by binary (symmetrical and asymmetrical) and multiple (coupled and/or sequential) cell fission. Although no clues concerning physiology or affinity of the studied cells can be drawn basing on their division mode, the identified reproductive patterns link them particularly closely with coccoidal microbes classified within the cyanobacterial group Pleurocapsales.

Morphology, morphogenesis, and molecular phylogeny of a soil ciliate, Gonostomum kuehnelti Foissner, 1987 (Ciliophora, Hypotrichia), from northwestern China

ABSTRACTThe morphology and morphogenesis of the hypotrichous soil ciliate Gonostomum kuehnelti Foissner, 1987, isolated from northwestern China, was investigated based on observations of live and protargol-stained specimens. Photomicrographs and some detailed morphological information, e.g. cortical granules and the number of dorsal kineties, are provided in this study. The morphogenesis of our population agrees in most details with that of the type population. The main events during binary fission are as follows: (1) the parental adoral zone of membranelles is retained completely; (2) six streaks of the undulating membranes and cirral anlagen are segmented in a 1: 2: 2: 2: 4: 4 pattern from left to right, and form three frontal, two frontoventral, one buccal, two frontoterminal, three postoral ventral, two pretransverse ventral, and two transverse cirri, respectively; and (3) the marginal rows and dorsal kineties develop intrakinetally. In addition, the SSU rDNA sequence of G. kuehnelti is provided. Phylogenetic analyses based on SSU rDNA sequences show that the genus Gonostomum is non-monophyletic and G. kuehnelti is placed within the core clade of Gonostomum.

Autoantibodies in Systemic Lupus Erythematosus Target Mitochondrial RNA.

The mitochondrion supplies energy to the cell and regulates apoptosis. Unlike other mammalian organelles, mitochondria are formed by binary fission and cannot be directly produced by the cell. They contain numerous copies of a compact circular genome that encodes RNA molecules and proteins involved in mitochondrial oxidative phosphorylation. Whereas, mitochondrial DNA (mtDNA) activates the innate immune system if present in the cytosol or the extracellular milieu, it is also the target of circulating autoantibodies in systemic lupus erythematosus (SLE). However, it is not known whether mitochondrial RNA is also recognized by autoantibodies in SLE. In the present study, we evaluated the presence of autoantibodies targeting mitochondrial RNA (AmtRNA) in SLE. We quantified AmtRNA in an inducible model of murine SLE. The AmtRNA were also determined in SLE patients and healthy volunteers. AmtRNA titers were measured in both our induced model of murine SLE and in human SLE, and biostatistical analyses were performed to determine whether the presence and/or levels of AmtRNA were associated with clinical features expressed by SLE patients. Both IgG and IgM classes of AmtRNA were increased in SLE patients (n = 86) compared to healthy controls (n = 30) (p < 0.0001 and p = 0.0493, respectively). AmtRNA IgG levels correlated with anti-mtDNA-IgG titers (rs = 0.54, p < 0.0001) as well as with both IgG and IgM against β-2-glycoprotein I (anti-β2GPI; rs = 0.22, p = 0.05), and AmtRNA-IgG antibodies were present at higher levels when patients were positive for autoantibodies to double-stranded-genomic DNA (p < 0.0001). AmtRNA-IgG were able to specifically discriminate SLE patients from healthy controls, and were negatively associated with plaque formation (p = 0.04) and lupus nephritis (p = 0.03). Conversely, AmtRNA-IgM titers correlated with those of anti-β2GPI-IgM (rs = 0.48, p < 0.0001). AmtRNA-IgM were higher when patients were positive for anticardiolipin antibodies (aCL-IgG: p = 0.01; aCL-IgM: p = 0.002), but AmtRNA-IgM were not associated with any of the clinical manifestations assessed. These findings identify mtRNA as a novel mitochondrial antigen target in SLE, and support the concept that mitochondria may provide an important source of circulating autoantigens in SLE.

Functional Analyses of Cytokinesis Regulators in Bloodstream Stage Trypanosoma brucei Parasites Identify Functions and Regulations Specific to the Life Cycle Stage.

The early divergent protozoan parasite Trypanosoma brucei alternates between the insect vector and the mammalian hosts during its life cycle and proliferates through binary cell fission. The cell cycle control system in T. brucei differs substantially from that in its mammalian hosts and possesses distinct mitosis-cytokinesis checkpoint controls between two life cycle stages, the procyclic form and the bloodstream form. T. brucei undergoes an unusual mode of cytokinesis, which is controlled by a novel signaling cascade consisting of evolutionarily conserved protein kinases and trypanosome-specific regulatory proteins in the procyclic form. However, given the distinct mitosis-cytokinesis checkpoints between the two forms, it is unclear whether the cytokinesis regulatory pathway discovered in the procyclic form also operates in a similar manner in the bloodstream form. Here, we showed that the three regulators of cytokinesis initiation, cytokinesis initiation factor 1 (CIF1), CIF2, and CIF3, are interdependent for subcellular localization but not for protein stability as in the procyclic form. Further, we demonstrated that KLIF, a regulator of cytokinesis completion in the procyclic form, plays limited roles in cytokinesis in the bloodstream form. Finally, we showed that the cleavage furrow-localizing protein FRW1 is required for cytokinesis initiation in the bloodstream form but is nonessential for cytokinesis in the procyclic form. Together, these results identify conserved and life cycle-specific functions of cytokinesis regulators, highlighting the distinction in the regulation of cytokinesis between different life cycle stages of T. bruceiIMPORTANCE The early divergent protozoan parasite Trypanosoma brucei is the causative agent of sleeping sickness in humans and nagana in cattle in sub-Saharan Africa. This parasite has a complex life cycle by alternating between the insect vector and the mammalian hosts and proliferates by binary cell fission. The control of cell division in trypanosomes appears to be distinct from that in its human host and differs substantially between two life cycle stages, the procyclic (insect) form and the bloodstream form. Cytokinesis, the final step of binary cell fission, is regulated by a novel signaling cascade consisting of two evolutionarily conserved protein kinases and a cohort of trypanosome-specific regulators in the procyclic form, but whether this signaling pathway operates in a similar manner in the bloodstream form is unclear. In this report, we performed a functional analysis of multiple cytokinesis regulators and discovered their distinct functions and regulations in the bloodstream form.

On Ternary Fission Induced by Neutrons

Experiments on measuring the rotational effect of the 234U fissile nucleus at the scission point showed that the fissile nucleus rotates as a right screw with respect to the longitudinally polarized neutron beam direction in the ternary fission of the 233U target nucleus induced by polarized s-neutrons; in the binary fission of the same nuclei it rotates in the opposite direction. Moreover, it was found that ternary fission “prefers” the spin state of J = I +1/2. This phenomenon cannot be explained within the existing concepts of ternary fission as one of the two “final” states after neck rupture. The same “parent” 234U nucleus cannot rotate in opposite directions in the two different final states. It should be assumed that ternary fission is a special branch of descent from the saddle point to the point of neck rupture. It can also be assumed that this branch is formed at the saddle point in a configuration favorable for cluster formation. Why does it prefer the spin state of J = I + 1/2? This is an interesting question for further studies.

Methylopila carotae sp. nov., a facultative methylotroph, isolated from a root of Daucus carota L.

An aerobic facultatively methylotrophic bacterium, designated strain Das4.1T, was isolated from a root of Daucus carota L. The cells of this strain were observed to be Gram-stain negative, asporogenous, non-motile short rods multiplying by binary fission. Strain Das4.1T can utilise methanol, methylamine and a variety of polycarbon compounds as carbon and energy sources. C1-compounds were found to be assimilated via the isocitrate lyase-negative variant of the serine pathway. On medium with 0.5% methanol, growth of strain Das4.1T was observed at pH 5.5-9.0 (optimum, pH 6.0-7.0) and 18-37°C (optimum, 24-29°C) and in the presence of 0-2% (w/v) NaCl (optimum, 0.05%). Cells are catalase and oxidase positive and synthesise indole from L-tryptophan. The major fatty acids of methanol-grown cells were identified as C18:1ω7c, C18:0 and 11-methyl-C18:1ω7c. The predominant phospholipids were found to be phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylmonomethylethanolamine. The major respiratory quinone was identified as Q-10. The DNA G + C content of strain Das4.1T was determined to be 67.3mol% (Tm). Phylogenetic analysis based on 16S rRNA gene sequence comparison revealed that strain Das4.1T belongs to the genus Methylopila and shows high sequence similarity to Methylopila oligotropha 2395AT (98.4%) and Methylopila capsulata IM1T (98.0%). However, the DNA-DNA relatedness of strain Das4.1T with M. oligotropha 2395AT was only 22 ± 3%. Based on genotypic, chemotaxonomic and physiological characterisation, the isolate can be classified as a novel species of the genus Methylopila, for which the name Methylopila carotae sp. nov. is proposed. The type strain is Das4.1T (= VKM B-3244T = CCUG 72399T).

Isotopic yield and half-life of spontaneous fission for Cn284 and Fl284 superheavy isobars using direct calculation and semiempirical formulas

Isotopic yields and half-lives of $^{284}\mathrm{Cn}$ and $^{284}\mathrm{Fl}$ superheavy nuclei are calculated using nuclear proximity and Coulomb potentials. The energy released in fission, $Q$ value, driving potential $(V\ensuremath{-}Q)$, the penetrability through barrier, fission decay constant, and relative yield for each possible pair of fission fragments are obtained. According to the fragments mass and charge asymmetry, the most favored binary fragmentation is occurred for the highest $Q$ value and the lowest driving potential. For spontaneous binary fission of $^{284}\mathrm{Cn}$ superheavy nuclei, the higher relative yields are belong to production of $^{128}\mathrm{Sn}$ and $^{134}\mathrm{Te}$ fragments and for $^{284}\mathrm{Fl}$ superheavy isotope, the maximum yield were observed for $^{136}\mathrm{Xe}$ as one of the fission fragments. The comparison between the obtained isotopic relative yield shows the role of magic and near-magic closed-shell fragments in having the highest isotopic yield. Fission decay constant for each possible fragmentation is calculated and then by summation over them, the total decay constant and fission half-life for $^{284}\mathrm{Cn}$ and $^{284}\mathrm{Fl}$ superheavy nuclei are estimated. Finally, the calculated half-lives using direct method are compared with the results of semiempirical formulas as well as experimental data. Satisfactory agreement is achieved between the results of this approach and the experimental data than the results of semiempirical formulas.

Scission point model for the mass distribution of ternary fission

A modified scission point model is adopted to study the mass distribution of thermal neutron induced binary and ternary fission of 235U. The scission configuration and the most favourable fragment deformation is identified through an energy balance criterion where the macroscopic part due to liquid drop and the microscopic part due to shell correction together with the deformation dependent interaction potential are used. The available energy for each channel together with fragment deformation is used to evaluate nuclear level densities in the Fermi gas model. Since the model is found to give the expected double humped mass distribution for binary fission of 236U, this is then applied for the ternary fission of the same nuclei with fixed third fragment. Two different third fragments with two cases of collinear arrangement were studied with the model. The obtained ternary mass distribution was then compared with the calculated binary mass distribution. In all the cases, the influence of shell effects is found to be prominent with one of the fragments associated with the Sn nucleus. The closed shell nuclei possess maximum yield in both binary and ternary mass distribution.

“Prison Break” Toxoplasma egress from infected cells is a tightly programmed event

The phylum Apicomplexa groups obligate intracellular parasites responsible for severe veterinary and human diseases. The most ubiquitous member of the phylum, Toxoplasma gondii establishes a life-long chronic infection in human and animals. Gliding motility, a substrate-dependent form of locomotion, powered by an actomyosin system, assists invasion and egress from the infected cells, two key steps in the lytic cycle of the Apicomplexa. Egress from infected cells is a temporally orchestrated process underpinned by the release of the apical secretory organelles termed micronemes. At any point during intracellular replication, T. gondii tachyzoites are able to egress in response to deleterious environmental changes by activation of the cGMP-dependent protein kinase (PKG). This leads to a raise in intracellular calcium and production of intracellular phosphatidic acid (PA), two key mediators of microneme exocytosis. We uncovered that in absence of alarming signals, a diacylglycerol kinase (DGK2) secreted into the parasitophorous vacuole, produces PA and dictates programmed egress that occurs after a defined number of cycles of binary fission. Parasites depleted in DGK2 fail to egress naturally and continue to replicate trapped in enlarged vacuoles that eventually rupture mechanically. In contrast these parasites readily respond to inducers of egress, glide and invade normally. The vacuolar production of the lipid mediator PA activates the transmembrane guanylate cyclase (GC) composed of one P4-ATPase and two guanylate cyclase domains. The signaling platform centered around GC and including two accessory proteins appears to integrate both intrinsic and extrinsic signals that trigger egress. While DGK2 governs natural egress of fast replicating tachyzoites, it is uncertain if and how slow growing encysted bradyzoites avoid to egress during chronic stage of infection. Support or Funding Information This research is supported by Swiss National Science Foundation and European Research Council under the European Union's Horizon 2020 Research and Innovation program under grant agreement no. 695596. HB is the recipient of a Swiss Government Excellence Scholarship with Uruguay Phosphatidic acid: a key lipid mediator of Toxoplasma egress from infected cells This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Teachers' Confidence to Integrate Biology in Agriscience Courses

The primary purpose of this study was to determine the confidence levels of School-based Agricultural Education (SBAE) teachers to integrate biology concepts in plant and animal science courses. The researchers also sought to describe the demographic characteristics of New Mexico SBAE teachers. This study used a descriptive-correlational research design. Teachers were asked to identify their confidence levels to teach the state standards of the animal science and plant science course that matched course objectives in biology and life science. The teachers had an average age of 39 and reported having an average of 13 years of teaching experience. The majority of New Mexico SBAE teachers received secondary science teacher certification and over 70% had obtained a master’s degree. Teachers felt the least confident to teach the processes of cell division, including binary fission, mitosis, and meiosis. Teachers felt the most confident integrating biology concepts within lessons dealing with the nutrients required by plants, how they obtain and transport those nutrients, as well as teaching the evolution of plants from green algae. The findings suggest that there are some relationships between years of teaching experience, school size, and teachers receiving the science certification.