How is the relationship between the C4 cereal Sorghum bicolor and the C3 root hemi-parasites Striga hermonthica and Striga asiatica affected by elevated CO2?

The C₄ cereal Sorghum bicolor was grown under either ambient (350 μmol mol^?1) or elevated (700 μmol mol^?1) [CO₂] in either the presence or absence of the C₃ obligate root hemi-parasites Striga hermonthica or S. asiatica. Both uninfected and infected sorghum plants were taller and had greater biomass, photosynthetic rates, water-use efficiencies and leaf areas under elevated compared with ambient [CO₂]. There was no evidence of any downregula-tion of photosynthesis in sorghum grown at elevated [CO₂]. Biomass of infected sorghum was lower under both ambient and elevated [CO₂], and although infected plants were larger under elevated [CO₂] the relative impact of infection on host biomass was either the same (S. asiatica) or only slightly less (S. hermonthica) than under ambient [CO₂]. In contrast, biomass of S. hermonthica and S. asiatica per host was lower under elevated than ambient [CO₂], although rates of photosynthesis were higher at elevated [CO₂] and parasite stomatal conductance was not responsive to [CO₂]. Parasites emerged above-ground and flowered earlier under ambient compared with elevated [CO₂]. It appears that the mechanism(s) by which the parasites affect host growth is (are) relatively insensitive to increased atmospheric [CO₂], although the parasites themselves were adversely affected by growth at elevated [CO₂].     

How and why does the proteome respond to microgravity?

For medical and biotechnological reasons, it is important to study mammalian cells, animals, bacteria and plants exposed to simulated and real microgravity. It is necessary to detect the cellular changes that cause the medical problems often observed in astronauts, cosmonauts or animals returning from prolonged space missions. In order for in vitro tissue engineering under microgravity conditions to succeed, the features of the cell that change need to be known. In this article, we summarize current knowledge about the effects of microgravity on the proteome in different cell types. Many studies suggest that the effects of microgravity on major cell functions depend on the responding cell type. Here, we discuss and speculate how and why the proteome responds to microgravity, focusing on proteomic discoveries and their future potential.     

How and why does the mitochondrial respiratory chain respond to light?

The plant mitochondrial respiratory system changes in its activity in response to light. This response has been thought to be important for ensuring cooperative function with the photosynthetic system. A recent study addressing light responses of the respiratory chain in Arabidopsis thaliana provided further insight into the role of mitochondria in illuminated leaves. Notably, the nonphosphorylating alternative oxidase is rapidly induced when plants are exposed to the high light stress, and appears to play a key role in keeping cellular redox balance.Key words: alternative oxidase, Arabidopsis thaliana, light acclimation, mitochondria, respiratory chain, organellar crosstalk     

Does photosynthetic acclimation to elevated CO2 increase photosynthetic nitrogen-use efficiency? A study of three native UK grassland species in open-top chambers

1. The photosynthetic response to elevated CO₂ and nutrient stress was investigated in Agrostis capillaris, Lolium perenne and Trifolium repens grown in an open-top chamber facility for 2 years under two nutrient regimes. Acclimation was evaluated by measuring the response of light-saturated photosynthesis to changes in the substomatal CO₂ concentration.
2. Growth at elevated CO₂ resulted in reductions in apparent Rubisco activity in vivo in all three species, which were associated with reductions of total leaf nitrogen content on a unit area basis for A. capillaris and L. perenne . Despite this acclimation, photosynthesis was significantly higher at elevated CO₂ for T. repens and A. capillaris , the latter exhibiting the greatest increase of carbon uptake at the lowest nutrient supply.
3. The photosynthetic nitrogen-use efficiency (the rate of carbon assimilation per unit leaf nitrogen) increased at elevated CO₂, not purely owing to higher values of photosynthesis at elevated CO₂, but also as a result of lower leaf nitrogen contents.
4. Contrary to most previous studies, this investigation indicates that elevated CO₂ can stimulate photosynthesis under a severely limited nutrient supply. Changes in photosynthetic nitrogen-use efficiency may be a critical determinant of competition within low nutrient ecosystems and low input agricultural systems.     

How did the amphibious Eleocharis vivipara acquire its C3-C4 photosynthetic plasticity?

<正>The recently published study by Liu et al.（2024） on a highquality,chromosome-level genome of Eleocharis vivipara provides new insight into the multiple evolution of C₄ photosynthesis in Cyperaceae and in particular in Eleocharis.The species studied has the rare feature of alternately using C₃photosynthesis underwater and C₄ photosynthesis on land（Ueno et al.,1988）,making it an exciting model to better understand the genetic control and evolution of the C₄ trait and,in particular,the evolutionary challenge to switch from C₃ to C₄photosynthesis from the aquatic to the terrestrial environment.This may imply both the control of genes involved in the C₄pathway and deep cellular anatomical changes.Alternately using C₃ or C₄ photosynthesis may also lead to evolutionary trade-offs （e.g.,optimization of photosynthetic enzymes in contrasting C₃ and C₄ biochemical contexts）.Maintaining C₃ and C₄ genes may therefore be necessary;hybridization（e.g.,allopolyploidization） between non-C₄ and C₄ taxa could have been involved to favor the emergence of such facultative photosynthetic strategy.     

Mechanical stabilization of desiccated vegetative tissues of the resurrection grass Eragrostis nindensis: does a TIP 3;1 and/or compartmentalization of subcellular components and metabolites play a role?

During dehydration, numerous metabolites accumulate in vegetative desiccation-tolerant tissues. This is thought to be important in mechanically stabilizing the cells and membranes in the desiccated state. Non-aqueous fractionation of desiccated leaf tissues of the resurrection grass Eragrostis nindensis (Ficalho and Hiern) provided an insight into the subcellular localization of the metabolites (because of the assumptions necessary in the calculations the data must be treated with some caution). During dehydration of the desiccant-tolerant leaves, abundant small vacuoles are formed in the bundle sheath cells, while cell wall folding occurs in the thin-walled mesophyll and epidermal cells, leading to a considerable reduction in the cross-sectional area of these cells. During dehydration, proline, protein, and sucrose accumulate in similar proportions in the small vacuoles in the bundle sheath cells. In the mesophyll cells high amounts of sucrose accumulate in the cytoplasm, with proline and proteins being present in both the cytoplasm and the large central vacuole. In addition to the replacement of water by compatible solutes, high permeability of membranes to water may be critical to reduce the mechanical strain associated with the influx of water on rehydration. The immunolocalization of a possible TIP 3;1 to the small vacuoles in the bundle sheath cells may be important in both increased water permeability as well as in the mobilization of solutes from the small vacuoles on rehydration. This is the first report of a possible TIP 3;1 in vegetative tissues (previously only reported in orthodox seeds).     

Binding of HIV-1 virions to α4β7 expressing cells and impact of antagonizing α4β7 on HIV-1 infection of primary CD4+ T cells

HIV-1 envelope glycoprotein is reported to interact with α4β7, an integrin mediating the homing of lymphocytes to gut-associated lymphoid tissue, but the significance of α4β7 in HIV-1 infection remains controversial. Here, using HIV-1 strain Ba L, the gp120 of which was previously shown to be capable of interacting with α4β7, we demonstrated that α4β7 can mediate the binding of whole HIV-1 virions to α4β7-expressing transfectants. We further constructed a cell line stably expressing α4β7 and confirmed the α4β7-mediated HIV-1 binding. In primary lymphocytes with activated α4β7 expression, we also observed significant virus binding which can be inhibited by an anti-α4β7 antibody. Moreover, we investigated the impact of antagonizing α4β7 on HIV-1 infection of primary CD4+ T cells. In α4β7-activated CD4+ T cells, both anti-α4β7 antibodies and introduction of shorthairpin RNAs specifically targeting α4β7 resulted in a decreased HIV-1 infection. Our findings indicate that α4β7 may serve as an attachment factor at least for some HIV-1 strains. The established approach provides a promising means for the investigation of other viral strains to understand the potential roles of α4β7 in HIV-1 infection.     

Interactions of elevated carbon dioxide and temperature with aphid feeding on transgenic oilseed rape: Are Bacillus thuringiensis (Bt) plants more susceptible to nontarget herbivores in future climate?

Climate change factors such as elevated carbon dioxide (CO₂) and temperature typically affect carbon (C) and nitrogen (N) dynamics of crop plants and the performance of insect herbivores. Insect‐resistant transgenic plants invest some nutrients to the production of specific toxic proteins [i.e. endotoxins from Bacillus thuringiensis (Bt)], which could alter the C–N balance of these plants, especially under changed abiotic conditions. Aphids are nonsusceptible to Lepidoptera‐targeted Bt Cry1Ac toxin and they typically show response to abiotic conditions, and here we sought to discover whether they might perform differently on compositionally changed Bt oilseed rape. Bt oilseed rape had increased N content in the leaves coupled with reduced total C compared with its nontransgenic counterpart, but in general the C : N responses of both plant types to elevated CO₂ and temperature were similar. Elevated CO₂ decreased N content and increased C : N ratio of both plant types. Elevated temperature increased C and N contents, total chlorophyll and carotenoid concentrations under ambient CO₂, but decreased these under elevated CO₂. In addition, soluble sugars were increased and starch decreased by elevated temperature under ambient but not under elevated CO₂, whereas photosynthesis was decreased in plants grown under elevated temperature in both CO₂ levels. Myzus persicae, a generalist aphid species, responded directly to elevated temperature with reduced developmental time and decreased adult and progeny weights, whereas the development of the Brassica specialist Brevicoryne brassicae was less affected. Feeding by M. persicae resulted in an increase in the N content of oilseed rape leaves under ambient CO₂, indicating the potential of herbivore feeding itself to cause allocation changes. The aphids performed equally well on both plant types despite the differences between C–N ratios of Bt and non‐Bt oilseed rape, revealing the absence of plant composition‐related effects on these pests under elevated CO₂, elevated temperature or combined elevated CO₂ and temperature conditions.     

How does the longevity of <Emphasis Type="Italic">Sasa kurilensis</Emphasis> ramets respond to a light gradient? An analysis of ontogenetic changes to hydraulic resistance and carbon budget within a ramet

We investigated how Sasa kurilensis ramet longevity differs under three light conditions. Ramet longevity is an important factor affecting the abundance of ramet populations and their biomass. The objectives of this study were to clarify: (1) whether ramet longevity varies spatially along a gradient of light conditions; (2) whether physiological functions, including water transport in culms, change with ontogenesis; (3) whether ramet longevity is associated with the most effective turnover for gaining a carbon profit within a ramet following a cost-benefit model or is affected by other factors such as death caused by a decline in physiological function. We analyzed S. kurilensis ramet longevity, hydraulic resistance, photosynthetic rate, and carbon content. We then estimated the ramet carbon budget. The longevity of S. kurilensis ramets was 2.8–4.5 years in Beneath-patch plots, 5.8–8.7 years in Edge-patch plots, and 1.6–2.2 years in Open-patch plots. Although leaf photosynthetic activity was stable, the instantaneous photosynthetic rate decreased during clear days in the open area. This may have been due to increased ramet hydraulic resistance. The rotation period of the most efficient carbon budget quantified by ecophysiological measurements was consistent with ramet longevity in Open-patch (2 years) and Edge-patch (5 years) sites. Meanwhile, the longevity of ramets grown under canopies was inconsistent with the cost-benefit model rules for a carbon budget because the carbon gain was low throughout the ramet life span.     

How does the ratio of ATP yield from the complete oxidation of palmitic acid to that of glucose compare with the relative energy contents of fat and carbohydrate?

The authors of many recent popular textbooks of biochemistry quote values for the ‘energy content’ of triacylglcyerol and dry carbohydrate on a weight basis as well as presenting calculations for the yield of ATP obtained when a molecule of glucose, or palmitic acid, is completely oxidised to CO₂ and H₂O. By extending these calculations and computing the yield of ATP in terms of the weight of glucose or palmitic acid oxidised to CO₂ and H₂O, it can be shown that the value for the ratio of the energy content of fat to that of carbohydrate is almost identical to the ratio of the yield of ATP per gram of palmitic acid oxidised, compared with that of glucose. Therefore, the efficiency (on a per gram basis) by which energy is made available as ATP is comparable for both the oxidation of fat and carbohydrate, thus underscoring the fact that the catabolic pathways for both fat and carbohydrate ultimately use the same means of generating ATP, namely, oxidative phosphorylation.     

Syntheses and crystal structures of the first iridium complexes with m- and p-terphenyl (tp). {[Ir2(p-tp)(cod)2](BF4)2 · 2CH2Cl2}3 and [Ir(m-tp)(η-C5Me5)](BF4)2

Novel two iridium terphenyl complexes were prepared and their structures were characterized crystallographically. The reaction of [Ir(cod)₂]BF₄ with p-terphenyl (p-tp) in CH₂Cl₂ was carried out to afford dinuclear Ir(I) complex {[Ir₂(p-tp)(cod)₂](BF₄)₂ · 2CH₂Cl₂}₃ (cod=1,5-cyclooctadiene) (1 · 2CH₂Cl₂), whereas the reaction of the intermediate [Ir(η⁵-C₅Me₅)(Me₂CO)₃]³⁺ in Me₂CO with m-terphenyl (m-tp) was done to provide mononuclear Ir(III) complex [Ir(m-tp)(η⁵-C₅Me₅)](BF₄)₂ (2). In complex 1 · 2CH₂Cl₂, two Ir atoms are η⁶-coordinated to both sides of terminal benzene rings from the upper and lower sides in the p-tp ligand, while one Ir atom is η⁶-coordinated to one side of the terminal benzene ring in the m-tp ligand in complex 2. Each crystal structure describes the first coordination mode found in metal complexes with the m- and p-tp ligands.     

The crystal structures of NSF3 and (NSF2N(CH3)CH2-)2: How short is the ‘Crystallographic’ NS triple bond?

The synthesis of the first unequivocally characterised bis(difluorothiazyne), [NSF₂N(CH₃)CH₂-]₂ is reported. The crystal structures of this and NSF₃ are also reported. NSF₃ has the same geometrical parameters, within error, as it does in the gas phase. PIXEL calculations show that the principal interactions in its crystal structure are SN?SN dipolar contacts, which form chains with S?N = 3.533(2) Å. These contacts are reminiscent of those observed in the crystal structures of ketones. The exchange of a fluorine by a dialkylamino group has almost no influence on the NS bond distance while the SF bonds are significantly elongated. This behaviour is explained by negative hyperconjugation and confirmed by experimental data (as far as available) and quantum chemical calculations for NSF_n(NMe₂)_3−n and NSF_nPh_3−n (n = 1-3).     

Plasma levels of the methyl ester of 15-methyl PGF2α in connection with intravenous and vaginal administration to the human

After intravenous injection of the methyl ester of 15-methyl-PGF_2α the drug initially disappeared faster than the corresponding free acid, but still after one hour, about 1% of the active drug is circulating in plasma. Vaginal administration of single suppositories containing 1 mg of 15-methyl-PGF_2α methyl ester and determination of plasma levels using gas chromatography - mass spectrometry demonstrated that the highest plasma levels were reached after 1.5 - 3 hours.Vaginal suppositories were administered according to different dose schedules for induction of abortion and plasma levels of 15-methyl-PGF_2α and it's ester were determined. There seemed to be a gross correlation between given doses and obtained plasma level. The data will serve as basis for further development of vaginal delivery devices.