Infrared Photography

Although literacy plays a large role in elementary science classrooms, one thing that offers a challenge for educators is meeting the linguistic needs of English language learners (ELLs) while also meeting their content needs. An additional challenge is ensuring that academic literacy extends beyond the classroom. This article presents ways of extending classroom literacy into the home. The suggestions and activities emphasize literacy strategies appropriate for ELLs as well as English-speaking students.     

Helping Students Distinguish between Mixtures and Chemical Compounds

For most middle school-level students, summarizing main ideas can prove to be difficult, especially for those with low vocabulary and language acquisition skills. Working specifically with students who are English Language Learners (ELLs) and in a special education program, we discovered that teaching summarization as a reading strategy increased students' abilities to (a) acquire and use information and (b) better comprehend science concepts. In combination with other vocabulary attainment activities, summary frames enhanced the students' ability to apply information to discussions, laboratory reports, and projects. In this article, we demonstrate how to use the summary frame strategy in the context of a lesson on cells. This lesson allows for (a) knowledge of terminology through vocabulary card activities, (b) comprehension of concepts presented through summary frame activities, and (c) application of concepts through cell models and organelle classroom responsibilities.     

Sweet Science for ALL! Supporting Inquiry-Based Learning Through M&Ms Investigation for English Language Learners

This article describes a series of inquiry-based lessons that provide English language learners (ELLs) with opportunities to experience science and engineering practices with conceptual understanding as well as to develop their language proficiency in elementary classrooms. The four-lesson sequence models how various types of instructional strategies for ELLs can be embedded through science lessons with thoughtful consideration of ELLs’ diverse cultural backgrounds. The cross-curricular science lessons provide ELLs with opportunities to apply and enhance their mathematics, reading, writing, and communicating skills while investigating the properties of M&Ms.     

Native language background and academic achievement: Is socioemotional well-being a mediator?

This study examined the extent to which socioemotional well-being mediated the relationship between language status and achievement, while exploring variability in this relationship based on informant (student versus teacher reports of socioemotional problems) and native language background (Spanish-speaking English language learners [ELLs] versus ELLs from Asian-language backgrounds). Participants included 9,046 fifth-grade students from the Early Childhood Longitudinal Study-Kindergarten Cohort of 1998. Results from structural equation modeling showed that Spanish-speaking ELLs reported more social-emotional problems as compared to English-monolingual (EM) and Asian-language ELL classmates in third grade, which partially explained their lower achievement levels in fifth grade. The model accounted for approximately 34% of the variance in students’ academic achievement in fifth grade (R² = .343, p < .001). When comparing ELL and EM students, results differed when using teachers’ versus students’ reports of socioemotional well-being. For both Spanish-speaking and Asian-language ELLs, teachers perceived fewer social and emotional difficulties than the students themselves reported in comparison to their EM classmates.     

Responses of Ribulose-1,5-Bisphosphate Carboxylase,Cytochrome f,and Sucrose Synthesis Enzymes in Rice Leaves to Leaf Nitrogen and Their Relationships to Photosynthesis

The photosynthetic gas-exchange rates and various biochemical components of photosynthesis, including ribulose-1,5-bisphosphate carboxylase (Rubisco) content, cytochrome (Cyt) f content, and the activities of two sucrose synthesis enzymes, were examined in young, fully expanded leaves of rice (Oryza sativa L.) grown hydroponically in different nitrogen concentrations. The light-saturated rate of photosynthesis at an intercellular CO2 pressure of 20 Pa (CO2-limited photosynthesis) was linearly dependent on leaf nitrogen content, but curvilinearly correlated with Rubisco content. This difference was due to a greater than proportional increase in Rubisco content relative to leaf nitrogen content and the presence of a CO2 transfer resistance between the intercellular air spaces and the carboxylation sites. CO2-limited photosynthesis was proportional to Cyt f content, one of the key components of electron transport, but was not proportional to the activities of cytosolic fructose-1,6-bisphosphatase and sucrose phosphate synthase, the two regulatory enzymes of sucrose synthesis. Light-saturated photosynthesis above an intercellular CO2 pressure of 60 Pa (CO2-saturated photosynthesis) was curvilinearly dependent on leaf nitrogen content. This CO2-saturated photosynthesis was proportional to Cyt f content in the low- and normal-nitrogen leaves, and correlated better with the activities of cytosolic fructose-1,6-bisphosphatase and sucrose phosphate synthase in the high-nitrogen leaves. The increase in the activities of these two enzymes with increasing leaf nitrogen was not as great as the increase in Cyt f content. Thus, as leaf nitrogen increased, the limitation caused by the activities of sucrose synthesis enzymes came into play, which resulted in the curvilinear relationship. However, this limitation by sucrose synthesis enzymes did not affect photosynthesis under normal ambient air.     

黄河流域植被光合动态时空演变及归因分析——基于日光诱导叶绿素荧光数据

植被光合作用是维持区域生态平衡和气候稳定的关键过程之一,对了解区域生态系统的健康状况和应对气候变化具有重要意义。基于GOSIF数据,对2001-2021年黄河流域植被光合的时空变化规律及原因进行了分析。结果表明:(1)黄河流域植被光合总体呈上升趋势,在空间上表现为西部和东南部高、北部低的分布格局。其中关中平原、阿尼玛卿山、宁夏平原以及黄河三角洲地区的植被光合呈现出显著退化的趋势。(2)归因分析结果表明,不同气候要素对植被光合动态的影响具有显著差异,总体上降水和太阳辐射与黄河流域的植被光合动态呈现出正相关,而温度与植被光合动态呈现出负相关。气候变化和人类活动对黄河流域植被光合动态具有不同程度的影响。人类活动(76.24%)对植被改善区域的贡献远大于气候变化(23.76%)。在退化区域中,稀树草原和农田中的气候变化贡献大于人类活动,灌木、草地和湿地中的人类活动贡献大于气候变化,林地中的气候变化贡献与人类活动相当。研究结果有助于更好理解黄河流域植被光合作用的变化机制,为黄河流域生态保护和高质量发展以及气候变化研究提供了重要的参考依据。     

The activity of uridine diphosphate glucose-d-fructose 6-phosphate 2-glucosyltransferase in leaves

1. By using EDTA in reaction mixtures it was possible to determine the activity of sucrose phosphate synthetase in freshly prepared leaf extracts without the complications caused by sucrose phosphatase. 2. EDTA was found also to increase the activity of sucrose phosphate synthetase by as much as 100%. 3. High sucrose phosphate synthetase activities were found in leaf preparations in which sucrose phosphatase was inhibited by EDTA. By contrast with previous reports, the activities were sufficient to allow sucrose synthesis in leaves during photosynthesis to occur via sucrose phosphate. 4. Sugar-cane plants having different rates of photosynthesis also had different activities of sucrose phosphate synthetase in their leaves. 5. It is suggested that the activity of sucrose phosphate synthetase in leaves may play a role in the control of the rate of photosynthesis.     

不同浓度镉胁迫对稗草生理特性的影响

通过室外盆栽法研究不同浓度镉(Cd)对稗草Echinochloa crusgalli生理特性的影响。结果表明,0.3 mg·kg-1 Cd2+胁迫增强稗草分蘖期的光合作用及抗氧化酶活性;但0.6、0.9 mg·kg-1 Cd2+胁迫抑制分蘖期稗草的光合作用,增强抗氧化酶活性以及提高MDA含量;3.0 mg·kg-1 Cd2+胁迫提高稗草分蘖期的抗氧化酶活性;6.0 mg·kg-1 Cd2+胁迫增加稗草分蘖期MDA含量。Cd2+浓度为0.6、6.0 mg·kg-1将抑制稗草抽穗期的光合作用,高浓度镉胁迫抑制稗草抽穗期的抗氧化酶活性。不同浓度镉胁迫下,稗草的脯氨酸含量较高,表现出较高的抗逆能力。     

Diurnal and seasonal variations of nitrogen fixation and photosynthesis in cyanobacterial mats

In situ measurements of nitrogenase activity and photosynthesis were performed simultaneously in cyanobacterial mats of intertidal sand flats of the Southern North Sea. Two types of cyanobacterial mats, which differed in species composition and biomass content, were investigated. The measurements were done monthly during 3 years to detect seasonal variations of nitrogen fixation and photosynthesis. Diurnal variations were investigated as well. The results showed that (i) freshly colonized sediment with the cyanobacteriumOscillatoria limosa as the dominant organism revealed the highest specific nitrogenase activities (ii) nitrogenase activities were highest in spring and summer, when mat development was initiated and (iii) diurnal fluctuations of nitrogenase activity indicated that it occurred temporally separated from oxygenic photosynthesis.     

Ancient origin of elicitin gene clusters in Phytophthora genomes

The genus Phytophthora belongs to the oomycetes in the eukaryotic stramenopile lineage and is comprised of over 65 species that are all destructive plant pathogens on a wide range of dicotyledons. Phytophthora produces elicitins (ELIs), a group of extracellular elicitor proteins that cause a hypersensitive response in tobacco. Database mining revealed several new classes of elicitin-like (ELL) sequences with diverse elicitin domains in Phytophthora infestans, Phytophthora sojae, Phytophthora brassicae, and Phytophthora ramorum. ELIs and ELLs were shown to be unique to Phytophthora and Pythium species. They are ubiquitous among Phytophthora species and belong to one of the most highly conserved and complex protein families in the Phytophthora genus. Phylogeny construction with elicitin domains derived from 156 ELIs and ELLs showed that most of the diversified family members existed prior to divergence of Phytophthora species from a common ancestor. Analysis to discriminate diversifying and purifying selection showed that all 17 ELI and ELL clades are under purifying selection. Within highly similar ELI groups there was no evidence for positively selected amino acids suggesting that purifying selection contributes to the continued existence of this diverse protein family. Characteristic cysteine spacing patterns were found for each phylogenetic clade. Except for the canonical clade ELI-1, ELIs and ELLs possess C-terminal domains of variable length, many of which have a high threonine, serine, or proline content suggesting an association with the cell wall. In addition, some ELIs and ELLs have a predicted glycosylphosphatidylinositol site suggesting anchoring of the C-terminal domain to the cell membrane. The eli and ell genes belonging to different clades are clustered in the genomes. Overall, eli and ell genes are expressed at different levels and in different life cycle stages but those sharing the same phylogenetic clade appear to have similar expression patterns.     

Bears in a boat: Science content and language development through a problem-based learning experience

In Problem-Based Learning (PBL), a problem is posed before students have learned how to solve it. Language and PBL pair well for effective learning environments. Informed by language-based theories of learning and strategically adding methods for working with English Language Learners (ELLs), we developed an approach called Problem-Based Enhanced-Language Learning. In this article, we provide the background for the approach and explain the specifics of implementing Bears in a Boat, which we have used in many contexts including a second-grade urban classroom and a third-grade US-Mexico border classroom with significant numbers of ELLs. The science content learner outcomes are that students will be able to: (a) describe what it means to sink and float and (b) explain that the more weight you add to a boat, the deeper it will float.     

Influence of Algal Photosynthesis on Biofilm Bacterial Production and Associated Glucosidase and Xylosidase Activities

Natural photosynthetic biofilms were incubated under light (100 mmol m-2 s-1) and dark conditions to elucidate the impact of photosynthesis on bacterial production, abundance, biovolume, biomass, and enzyme activities over 24 h. Use of organic carbon-free media limited carbon sources to algal photosynthesis and possibly the polysaccharides of the biofilm matrix. Bacterial production of biofilm communities was significantly higher in light incubations (p <0.001). The greatest differences in production rates between light and dark incubations occurred between 8 and 24 h. Biomass-specific a- and b-glucosidase and b-xylosidase activities were stimulated by photosynthesis, with significantly greater activities occurring at hours 16 and 24 in the light treatment (p <0.01). The results indicate that algal photosynthesis can have a significant impact on bacterial productivity, biomass, biovolume, and enzyme production over longer time periods at low photon flux densities (?100 mmol m-2 s-1).     

Effects of grandinol and related phloroglucinol derivatives on transpiration and stomatal closure

Grandinol, an inhibitor of seed germination and photosynthesis in Eucalyptus sp., inhibits transpiration and stomatal opening. The acylphloroglucinol structure in grandinol seemed to be essential for these activities. Enhancement of activity was achieved by the introduction of a formyl group into the molecule. Therefore, structural requirements for these activities were very similar to that for the inhibition of seed germination and photosynthesis. Other grandinol-related compounds having two electron-withdrawing groups on the phloroglucinol nuclei were also active in these assays.     

冰冻对珊瑚树(Viburnum odoratissimum)叶片光合效率的影响

光合作用的冰冻伤害研究大多利用离体叶片、原生质体,甚至叶绿体类囊体进行人工冰冻预处理,关于室外自然温度下出现的植物光合作用冰冻伤害,特别是冰冻影响光合量子效率的研究报告还很少。虽然光合碳同化受抑是最早可以测到的冰冻伤害征状,但其机理迄今不清楚(Krause等1982,Krause和Klosson1983)。     

光周期对中国水螅种群增长、无性出芽生殖及抗氧化酶活力的影响

单细胞真核绿藻在中国水螅(Hydra sinensis)内胚层皮肌细胞中共生是有较高科研价值的特殊生物学现象。水螅宿主细胞为共生藻提供CO2、氮源及矿物质,而共生藻通过光合作用可能为宿主提供碳水化合物等有机物营养,因此水螅与共生藻间代谢流是以共生藻光合作用为中心,但基于代谢流二者间的互作机制目前尚未阐明。水螅通过营养积累进行出芽生殖,从母体脱落的芽体数量间接反映水螅营养积累的相对量。而光暴露时长能影响共生绿藻光合作用,如果共生藻的确能向水螅细胞转移光合作用产物,那光暴露时长应该能间接影响水螅的营养积累、从而进一步影响水螅无性出芽生殖。为证实该假说,本研究应用种群累积培养法,观察了光周期对中国水螅种群增长、无性出芽生殖及抗氧化酶(SOD和CAT)活力的影响。结果显示,光周期对中国水螅种群增长具有明显的影响。培养15 d后,所有实验组水螅的种群密度均为正增长,其中8L∶16D(在一个24h周期内光暴露8 h、黑暗16 h)实验组种群密度最大、而0L∶24D(持续黑暗)实验组种群密度最小。另外,随着光暴露时长的增加,中国水螅SOD及CAT活力整体均呈下降趋势。结果表明,从光周期对中国水螅无性出芽生殖及两种抗氧化酶活力的影响来看,中国水螅对光周期的生理学响应较为敏感,这个现象可能源于共生绿藻能通过向宿主细胞转移光合作用产物的方式为水螅提供营养补充。     

Wild manihot species do not possess C4 photosynthesis

Cultivated cassava (Manihot esculenta) has a higher rate of photosynthesis than is usual for C3 plants and photosynthesis is not light saturated. For these reasons it has been suggested that cultivated cassava could be derived from wild species possessing C4 photosynthesis. The natural abundance of 13C and activities of phosphoenolpyruvate carboxylase and phosphoglycolate phosphatase were measured in leaves of 20 wild cassava species to test this hypothesis. All the species studied, including M. flabellifolia the potential wild progenitor of cultivated cassava, clearly exhibited C3 not C4 characteristics.     

Grafting helps improve photosynthesis and carbohydrate metabolism in leaves of muskmelon

The most important quality for muskmelon (Cucumis melo L.) is their sweetness which is closely related to the soluble sugars content. Leaves are the main photosynthetic organs in plants and thus the source of sugar accumulation in fruits since sugars are translocated from leaves to fruits. The effects of grafting muskmelon on two different inter-specific (Cucurbita maxima×C. moschata) rootstocks was investigated with respect to photosynthesis and carbohydrate metabolism. Grafting Zhongmi1 muskmelon on RibenStrong (GR) or Shengzhen1 (GS) rootstocks increased chlorophyll a, chlorophyll b and chlorophyll a+b content and the leaf area in middle and late developmental stages of the plant compared to the ungrafted Zhongmi1 check (CK). Grafting enhanced the net photosynthesis rate, the stomatal conductance, concentration of intercellular CO(2) and transpiration rate. Grafting influenced carbohydrates contents by changing carbohydrate metabolic enzymes activities which was observed as an increase in acid invertase and neutral invertase activity in the functional leaves during the early and middle developmental stages compared to CK. Grafting improved sucrose phosphate synthase and stachyose synthase activities in middle and late developmental stages, thus translocation of sugars (such as sucrose, raffinose and stachyose) in GR and GS leaves were significantly enhanced. However, compared with CK, translocation of more sugars in grafted plants did not exert feedback inhibition on photosynthesis. Our results indicate that grafting muskmelon on inter-specific rootstocks enhances photosynthesis and translocation of sugars in muskmelon leaves.     

A New Model for Leaf Photosynthesis Incorporating the Gradients of Light Environment and of Photosynthetic Properties of Chloroplasts within a Leaf

A leaf photosynthesis model was constructed based upon the notionthat the leaf photosynthesis is a summation of photosynthesisof each chloroplast under in situ micro-environmental conditions.Intra-leaf light environment was calculated using the valuesof transmittance and reflectance of leaf tissues reported previously.Simulations of light response curves of whole leaf photosynthesiswere carried out for the model leaves with different patternsof gradients in light environment and/or in photosynthetic activities.The results indicate that the higher absorption coefficientof chlorophyll in spongy tissue than in palisade tissue andintra-leaf vertical gradient in photosynthetic activity of thechloroplasts as reported for real dorsiventral leaves are bothadvantageous to the productivity of the leaf because these propertiesraise the efficiency of the light utilization. Intra-leaf light environment, leaf photosynthesis, light utilization, palisade tissue, photosynthetic productivity, spongy tissue     

Gas Law for the Classroom

The author provides information on how science teachers can write science literacy objectives that help English language learners (ELLs) develop the scientific literacy needed for academic success in the science classroom. The article offers suggestions on how teachers can determine the vocabulary, language functions, and sentence structures that their students need to engage in critical thinking in science. An approach for collaboration with students' English as a second language (ESL) teacher is discussed.     

CO2浓度升高对干旱胁迫下小麦光合作用和抗氧化酶活性的影响

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