The Kranz syndrome in the Eragrostideae (Chloridoideae, Poaceae) as indicated by carbon isotopic ratios*

Bothalia ◽  
1984 ◽  
Vol 15 (3/4) ◽  
pp. 587-590
Author(s):  
Hector O. Panarello ◽  
Evangelina Sanchez
Keyword(s):  
Mass Spectrometry ◽  
C4 Photosynthesis ◽  
Leaf Tissue ◽  
C4 Plants ◽  
C3 Plants ◽  
Isotopic Ratios ◽  
Carbon Isotope Ratios ◽  
Carbon Isotopic ◽  
Δ 13C ◽  
Kranz Leaf Anatomy

13C/12C ratios are generally regarded as being very reliable indicators of C3 or C4 photosynthesis. These relative carbon isotope ratios are expressed as a negative δ 3C and fall into two distinct groups: Kranz (or C4) plants with δ between -9°/00 no and -18°/00 and non-Kranz (C3) plants with δ between -22°/00 and -280/00 no. In this paper, 29 taxa, representing 12 genera, of the tribe Eragrostideae were examined by mass spectrometry for their δ 13C in dried leaf tissue. All these taxa proved to be C4, plants with δ13C values ranging between -13,6°/oo and -10.9°/oo. These findings confirmed published leaf anatomical observations which showed that all the studied taxa had characteristic Kranz leaf anatomy.

scholarly journals Challenges and Approaches to Crop Improvement Through C3-to-C4 Engineering

2021 ◽  
Vol 12 ◽  
Author(s):  
Hongchang Cui
Keyword(s):  
Photosynthetic Efficiency ◽  
C4 Photosynthesis ◽  
Crop Improvement ◽  
Bundle Sheath ◽  
C4 Plants ◽  
System Level ◽  
C3 Plants ◽  
World Population ◽  
Kranz Anatomy ◽  
The Past

With a rapidly growing world population and dwindling natural resources, we are now facing the enormous challenge of increasing crop yields while simultaneously improving the efficiency of resource utilization. Introduction of C4 photosynthesis into C3 crops is widely accepted as a key strategy to meet this challenge because C4 plants are more efficient than C3 plants in photosynthesis and resource usage, particularly in hot climates, where the potential for productivity is high. Lending support to the feasibility of this C3-to-C4 engineering, evidence indicates that C4 photosynthesis has evolved from C3 photosynthesis in multiple lineages. Nevertheless, C3-to-C4 engineering is not an easy task, as several features essential to C4 photosynthesis must be introduced into C3 plants. One such feature is the spatial separation of the two phases of photosynthesis (CO2 fixation and carbohydrate synthesis) into the mesophyll and bundle sheath cells, respectively. Another feature is the Kranz anatomy, characterized by a close association between the mesophyll and bundle sheath (BS) cells (1:1 ratio). These anatomical features, along with a C4-specific carbon fixation enzyme (PEPC), form a CO2-concentration mechanism that ensures a high photosynthetic efficiency. Much effort has been taken in the past to introduce the C4 mechanism into C3 plants, but none of these attempts has met with success, which is in my opinion due to a lack of system-level understanding and manipulation of the C3 and C4 pathways. As a prerequisite for the C3-to-C4 engineering, I propose that not only the mechanisms that control the Kranz anatomy and cell-type-specific expression in C3 and C4 plants must be elucidated, but also a good understanding of the gene regulatory network underlying C3 and C4 photosynthesis must be achieved. In this review, I first describe the past and current efforts to increase photosynthetic efficiency in C3 plants and their limitations; I then discuss a systems approach to tackling down this challenge, some practical issues, and recent technical innovations that would help us to solve these problems.

scholarly journals Resolving Whether Inhalation of Depleted Uranium Contributed to Gulf War Illness Using High-Sensitivity Mass Spectrometry

2020 ◽  
Author(s):  
Randall Parrish ◽  
Robert Haley
Keyword(s):  
Mass Spectrometry ◽  
High Precision ◽  
Inhalation Exposure ◽  
High Sensitivity ◽  
Gulf War ◽  
Depleted Uranium ◽  
Isotopic Ratios ◽  
Gulf War Illness ◽  
Case Definitions ◽  
Standard Case

Abstract Background: Of the hypothesized causes of Gulf War Illness (GWI), a chronic multi-symptom illness afflicting approximately 25 percent of >700,000 military personnel deployed to the 1991 Gulf War, depleted uranium (DU) and exposure to nerve agents have stimulated the most intense international concern. Past depleted uranium research on Gulf War veterans has measured urinary uranium concentration [U] and uranium isotopic ratios with low precision mass spectrometry primarily in GW veterans with retained shrapnel but has not used high precision mass spectrometry to test for an association of GWI with inhaled DU and we set out to test this potential association. Methods: We applied a standard biokinetic model to predict the urinary total [U] and uranium isotopic ratios in urine 18 years after inhalation exposure. We applied high sensitivity mass spectrometry methods capable of detecting the predicted levels in 154 individuals of a population-representative sample of U.S. veterans in whom Gulf War illness had been determined by standard case definitions and DU inhalation exposures obtained by medical history. Results: Methods used in past studies are capable of detecting only the high urinary uranium excretion levels from retained DU shrapnel but not lower levels predicted from DU inhalation. Using high precision mass spectrometry, we found no difference in the 238U/235U ratio in veterans meeting the standard case definitions of GWI versus control veterans, and no differences by levels of DU inhalation exposure. Our bivariate analysis of 236U/238U by 235U/238U showed only the signature of natural dietary uranium, excluding DU inhalation exposures above 0.4 mg, far below the disease-causing threshold. Conclusion: The findings by high precision mass spectrometry support the conclusion that even the highest levels of DU inhalation played no role in the development of Gulf War illness. Other factors including exposure to aerosolized organophosphate compounds (pesticides and sarin nerve agent) remain as the most likely cause(s) of GWI.

scholarly journals The chronology of Jäkärlä Ware – Bayesian interpretation of the old and new radiocarbon dates from Early and Middle Neolithic southwest Finland

2019 ◽  
Vol 46 ◽  
pp. 246-267
Author(s):  
Petro Pesonen ◽  
Markku Oinonen
Keyword(s):  
Isotopic Ratios ◽  
Stable Carbon ◽  
Radiocarbon Dates ◽  
Reservoir Effect ◽  
Carbon Isotopic ◽  
Potential Reservoir

The chronology of the eastern Fennoscandian Neolithic is organized with the help of pottery styles, one of which is southwestern Finnish Jäkärlä Ware. In this paper a number of new radiocarbon dates connected with Jäkärlä Ware and other relevant ceramic groups are presented and discussed. The radiocarbon dates of each group are modelled within a Bayesian chronological framework. Also, the potential reservoir effect in charred crust dates is estimated for each date based on stable carbon isotopic ratios of the crust samples and incorporated into models. Jäkärlä Ware appears to be a short-living and quite a isolated group, which had no chronological contacts with Sperrings 1–2 Wares, but with possible coexistence with Middle Neolithic Typical Comb Ware. Jäkärlä Ware is partly simultaneous with eastern Finnish asbestos-tempered Kaunissaari Ware, and forms with it a short chronological horizon in the turn of the Early and Middle Neolithic of eastern Fennoscandia.

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