Chlorophylls content

In a similar way, microalgal biomass on the sediment surface can be estimated by measuring the chlorophyll contents in benthic microalgae, which are single-celled microscopic plants that inhabit the top 0 to 3 cm of a sediment surface and are sometimes referred to as microphytobenthos. These organisms are the primary food resources of benthic grazers such as shellfish and numerous finfish species. 

The wide distribution of chlorophylls throughout the plant kingdom facilitates the scrutiny of chlorophyll-rich vegetables for human nutrition with a view to their direct consumption. However, until now, little standardized information was available in the literature regarding the absolute total chlorophyll contents and the ratios of chlorophylls a and b in raw materials. The different analytical methods of extraction and quantification and the lack of data about moisture contents (that may vary considerably among varieties and preparations) can also influence the final contents of pigments. These factors have largely contributed to the discrepancies found in similar food samples. 

Total Chlorophyll Contents of Some Vegetables and Fruits... 

As pheophytin a and pheophytin b are the major degradation derivatives formed during extraction, food processing, and storage, some authors reconunend converting chlorophylls into the more stable pheophytins by treatment with HCl, ion exchange resin, or oxalic acid to estimate the chlorophyll contents. ... 

All the analytical methods mentioned to separate, identify, and quantify chlorophylls and derivatives consume time, money, and samples. As alternatives, industries have been employing non-destructive methods for surface color measurements that are not only indirectly related to chlorophyll content, but may also estimate the pigments directly in tissues, leaving the sample intact and enabling serial analyses in a relatively short time. Eood color affects consumer acceptance and is an important criterion for quality control. Color vision is a complex phenomenon that depends on both the total content and number of pigments and also on absorption, reflectance and emission spectra of each compound present. 

Roca, M. and Mmguez-Mosquera, M.L, Involvement of chlorophyllase in chlorophyll metabolism in olive varieties with high and low chlorophyll content, Physiol. Plant, 117, 459, 2003. 

Sinnecker, P. et al.. Relationship between color (instrumental and visual) and chlorophyll contents in soybean seeds during ripening, J. Agric. Food Chem., 50, 3961, 2002. 

Figure 3. Effect of glyphosate on fresh weight (o), chlorophyll content (x), and anthocyanin content ( ) of excised buckwheat cotyledons after 24 h of treatment in the light. Reproduced with permission from Ref. 6. Copyright 1980, Plant Physiology.

Einhellig and Rasmussen (17) reported that In addition to ferulic and p-coumaric acids, vanillic acid reduced chlorophyll content of soybean leaves but did not affect chlorophyll In grain sorghum fSorghum bicolor (L.) Moench.]. It Is not known whether these reported mechanisms are primary or secondary events In the Inhibition of plant growth by allelochemlcals. 

Additional research with Lemna species has indicated that parameters other than direct growth measurements may be more sensitive In this bioassay. Table VII compares growth and chlorophyll content of L. minor as affected by catechln. Final frond number was inhibited by 1000 pM catechln and stimulated at lower concentrations of 50 and 100 pM. Chlorophyll content on a per-frond basis, however, was consistently Inhibited by catechln and was concentration dependent to 100 pM. 

TABLE VII. Effect of Catechln on the Growth and Chlorophyll Content of Lemna minor L. Growing In 24-well Tissue Culture Cluster Dishes... 

Menendez M, Herrera J, Comm FA (2002) Effect of nitrogen and phosphorus supply on growth, chlorophyll content and tissue composition of the macroalga Chaetomorpha linum (O.F. Mlill), Kiitz, in a Mediterranean Coastal Lagoon. Sci Mar 66 355-364... 

ALGAE (various species) 22 pg/L, 7 days No effect on photosynthesis rate, chlorophyll content, or cell numbers (Plumley and Davis 1980)... 

The marker enzymes used in this experiment are as follows vanadate-sensitive H+-ATPase (plasma membrane), nitrate-sensitive H+-ATPase or pyrophosphatase (tonoplast), TritonX-100 stimulated-UDPase or IDPase (Golgi complex), antimycin A-insensitive NADPH cytochrome c reductase (ER), and cytochrome c oxidase (mitochondria inner membrane). NADH cytochrome c reductase activity is found to be 10 times higher than NADPH cytochrome c reductase activity. Chlorophyll content can be measured as the chloroplast marker. The chlorophyll content is calculated by the following equation. Before measurement, auto zero is performed at 750 ran. 

Chlorophyll content ( S.D.) of four fresh and immediately frozen green leafy vegetables. 

Adedipe et a// found that Bel W, tobacco leaves were more sensitive to ozone when attached, rather than detached or used as leaf disks. Effects were seen as visual injury and change in chlorophyll content. 

Gymnopusin (18) also caused a signiftcant decrease in chlorophyll content at concentrations ranging from 50 JlM to 200 p.M (Fig. 4). Finally... 

---