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101.
Eya Khemis Mayssa Ben Mustapha Ikbel Chaieb Roberta Ascrizzi Guido Flamini Abdel Halim Harrath Hichem Ben Jannet Afifa Zardi-Bergaoui 《化学与生物多样性》2023,20(2):e202200646
Due to the several side effects of synthetic pesticides, including environmental pollution, threats to human health, and the development of pest resistance to insecticides, the use of alternative healthy, available and efficient agents in pest management strategies is necessary. Recently, the use of essential oil obtained from aromatic plants has shown significant potential for insect pest management. For this reason, the essential oil isolated from seeds of Thapsia garganica L. was investigated for the first time for its chemical profile, and its toxicity and repellency effects against Tribolium castaneum adults. Qualitative and quantitative analyses of the chemical composition by gas chromatography coupled to mass spectrometry (GC/MS) revealed the presence of 18 organic volatiles representing 96.8 % of the total constituents. The main compounds were 1,4-dimethylazulene (51.3 %) followed by methyl palmitate (8.2 %), methyl linoleate (6.2 %) and costol (5.1 %). Concerning the repellent effect, results revealed that SEO (Seed Essential Oil) was very repellent towards T. castaneum adults, with 100 % repellency after 2 h of exposure. Furthermore, the essential oil exhibited remarkable contact toxicity against T. castaneum (93.3 % of mortality) at the concentration of 10 % (v/v). The median lethal dose (LD50) of the topical application of the seed essential oil was 4.4 %. These encouraging outcomes suggested that the essential oil from T. garganica seeds could be considered a potent natural alternative to residual persistent and toxic insecticides. 相似文献
102.
Total DNA was isolated from 10 species of microalgae, including representatives of the Chlorophyceae (Chlorella ellipsoidea, Chlamydomonas reinhardtii, and Monoraphidium minutum), Bacillariophyceae (Cyclotella cryptica, Navicula saprophila, Nitzschia pusilla, and Phaeodactylum tricornutum), Charophyceae (Stichococcus sp.), Dinophyceae (Crypthecodinium cohnii), and Prasinophyceae (Tetraselmis suecica). Control samples of Escherichia coli and calf thymus DNA were also analyzed. The nucleoside base composition of each DNA sample was determined by reversed-phase high performance liquid chromatography. All samples contained 5-methyldeoxycytidine, although at widely varying levels. In M. minutum, about one-third of the cytidine residues were methylated. Restriction analysis supported this high degree of methylation in M. minutum and suggested that methylation is biased toward 5′-CG dinucleotides. The guanosine + cytosine (GC) contents of the green algae were, with the exception of Stichococcus sp., consistently higher than those of the diatoms. Monoraphidium minutum exhibited an extremely high GC content of 71%. Such a value is rare among eukaryotic organisms and might indicate an unusual codon usage. This work is important for developing strategies for transformation and gene cloning in these algae. 相似文献
103.
The influence of temperature on the biochemical composition of eight species of marine phytoplankton was investigated. Thalassiosira pseudonana Hasle and Heim-dal, Phaeodactylum tricornutum Bohlin and, Pavlova lutheri Droop (three of eight species studied) had minimum values of carbon and nitrogen quotas at intermediate temperatures resulting in a broad U-shaped response in quotas over the temperature range of 10 to 25°C. Protein per cell also had minimum values at intermediate temperatures for six species. For T. pseudonana, P. tricornutum, and P. lutheri, patterns of variation in carbon, nitrogen, and protein quotas as a function of temperature were similar. Over all species, lipid and carbohydrate per cell showed no consistent trends with temperature. Only chlorophyll a quotas and the carbon: chlorophyll a ratios (θ) showed consistent trends across all species. Chlorophyll a quotas were always lower at 10°C than at 25°C. Carbon: chlorophyll a ratios (θ) were always higher at 10°C than at 25°C. We suggest that although θ consistently increases at lower temperatures, the relationship between temperature and θ ranges from linear to exponential and is species specific. Accordingly, the interspecific variance in θ that results from species showing a range of possible responses to temperature increases as temperature declines and reaches a maximum at low temperatures. High photon flux densities appear to increase the potential interspecific variance in the carbon: chlorophyll a ratio and therefore exacerbate these trends. 相似文献
104.
Burkhard Becker Dieter Becker Johannis P. Kamerling Michael Melkonian 《Journal of phycology》1991,27(4):498-504
The chemical composition of cell walls (thecae) of three taxa of scaly green flagellates (Prasinophyceae) was investigated. The theca of Tetraselmis striata, Tetraselmis tetrathele, and Scherffelia dubia consists mainly of carbohydrate (80% of dry weight), with proteins (5%), calcium (4%), and sulfate (6%) as minor components. The principal sugars (60% of dry weight) are the 2-keto-sugar acids 3-deoxy-manno-2-octulosonic acid (KDO), 3-deoxy-manno-5-O-methyl-2-octulosonic acid (5OMeKDO), and 3-deoxy-lyxo-2-heptulosaric acid (DHA). Arabinose, gulose, galactose, galacturonic acid, and in S. dubia, xylose and rhamnose were also found. Examination of scale preparations from Mantoniella squamata, Mesostigma viride, Pyramimonas amylifera, and Nephroselmis olivacea revealed that the 2-keto-sugar acids were always associated with the presence of typical prasinophycean scales on the cell surface. In contrast, 2-keto-sugar acids were not detected in the cell wall of Chlamydomonas reinhardtii nor in polymer preparations from the culture medium of Chlamydomonas reinhardtii, Dunaliella bioculata, Dunaliella primolecta, Asteromonas gracilis, Hafniomonas reticulate, Pedinomonas tuberculata, Monomastix sp., and Micromonas pusilla. We conclude that 2-keto-sugar acids are chemical markers for prasinophycean scales. 相似文献
105.
106.
海甘蓝种子在成熟过程中,棕榈酸、硬脂酸和亚麻酸的含量不断下降,而二十碳烯酸和芥酸的含量呈上升趋势。选用开花后25~27d的海甘蓝幼胚分别在含不同浓度的ABA或高渗透剂的培养基中培养1~3d,发现其各种脂肪酸的变化趋势和种子自然成熟过程中脂肪酸的变化相似,说明ABA或高渗透剂可能是种子成熟过程中各种脂肪酸合成和相互转化所需的条件。 相似文献
107.
The present study was conducted to investigate the effect of zinc deficiency on fatty acid desaturation in rats fed two different
types of dietary fat, a mixture of coconut oil and safflower oil (7∶1, w/w, “coconut oil diet”) or linseed oil (“linseed oil
diet”). In order to ensure an adequate food intake, all rats were force-fed by gastric tube. Zinc deficiency caused statistical
significant reducion of Δ9-desaturase activity in liver microsomes of rats fed coconut oil diet and tendencial reduction (p<0.15) in rats fed linseed oil diet compared with control rats fed diets with the same type of fat. In agreement with this
effect, zinc deficiency in the rats fed both types of dietary fat increased the ratio between total saturated and total monounsaturated
fatty in liver phospholipids and liver microsomes. Zinc deficient rats on the coconut oil diet had unchanged Δ6-desaturase
activity with linoleic acid as substrate and lowered activity with α-linolenic acid as substrate. In contrast, zinc deficient
rats on the linseed oil diet had increased Δ6-desaturase activity with linoleic acid as substrate and unchanged activity with
α-linolenic acid. Because linoleic acid is the main substrate for Δ6-desaturase in the rats fed coconut oil diet, and α-linolenic
acid is the main substrate in the rats fed linseed oil diet, it is concluded that in vivo Δ6-desaturation was not changed
by zinc deficiency in the rats fed both types of dietary fat. Activity of Δ5-desaturase was also not changed by zinc deficiency
in the rats fed both dietary fats. Levels of fatty acids in liver phospholipids and microsomes derived by Δ4-, Δ5-, and Δ6-desaturation
were not consistently changed by zinc deficiency in the rats fed both types of dietary fat. Thus, the enzyme studies and also
fatty acid composition data of liver phospholipids and microsomes indicate that zinc deficiency does not considerably disturb
desaturation of linoleic and α-linolenic acid. Therefore, it is suggested that similarities between deficiencies of zinc and
essential fatty acids described in literature are not due to disturbed desaturation of linoleic acid in zinc deficiency. The
present study also indicates that zinc deficiency enhances incorporation of eicosapentaenoic acid into phosphatidylcholine
of rats fed diets with large amounts ofn-3 polyunsaturated fatty acids. 相似文献
108.
Photosynthetic pigments, C, N, and P tissue composition, and photosynthetic rate were measured from April to October in the brown alga Phyllariopsis purpurascens (C. Agardh) Henry et South (Laminariales, Phaeophyta) growing at a 30-m depth in the Strait of Gibraltar. Ir-radiance reaching the population ranged from 13.5 to 27.5 mol.m-2.mo-1. The available light for this species, expressed as a percentage of the irradiance above the water, was 1.8%. Dissolved inorganic nitrogen forms, NO3-and NH4+, were constant from April to October, whereas phosphate was depleted in August. Chlorophyll a decreased from 520.0 ± 165.0 to 199.6 ± 159.9 μg.g-1 dry weight; in contrast, chlorophyll c and carotenoids did not change until September but increased threefold in October. C:N and N:P ratios changed in the same way and in the same range. They were constant until July but increased from 15–17 up to 42 (C:N) and from 14 to 40 (N:P) in October, suggesting a severe P limitation of growth of this species. The dark respiration rate and the light compensation point were constant from April to October (0.5 ± 0.1 μmol O2. m-2.s-1 and 6.5 ± 0.2 μmol.m-2. s-1, respectively), whereas the maximum rate of apparent photosynthesis, light onset saturation parameter, and half saturation constant for light were maximum in April to May (3.7 μmol O2. m-2.s-1and 40 and 41.5 μmol.m-2. s-1, respectively) and October (3.6 μmol O2. m-2.s-1 and 50 and 53.7 μmol.m-2. s-1, respectively). They were minimum in August (1.2 μmol O2.m-2.s-1 and 11.3 and 12 μmol.m-2.s-1, respectively). These minimum figures yielded a negative carbon budget in August and 0 in September, whereas it was positive the rest of the year. Photosynthetic efficiency, estimated by the ratio between maximum apparent photosynthesis and light half saturation constant, showed a strong agreement with productivity measured by means of an independent method. These results indicate that lamina expansion in this species is controlled by photosynthetic efficiency. 相似文献
109.
We describe short-term changes in foraging behavior by wild Yakushima macaques (Macaca fuscata yakui),which inhabit a warm-temperate broad—leaved forest on Yakushima Island (30°N, 131°E), Japan. Rapid changes of dietary composition,
activity budget, and range use by the monkeys occurred from May to June, apparently associated with changes in the availability
of the fruit of Myrica rubraBefore the fruit ripened, monkeys spent less time moving and more time feeding on many species of leaves, which accounted
for 40% of feeding time. However, when M. rubrabegan to ripen, they fed intensively on the fruit, which accounted for three-fourths of feeding time,though the activity budget remained unaffected As fiuit of M. rubradecreased,the monkeys fed more on the fruit of other species and on insects, and spent more time moving at higher speeds. There marked
shifts in foraging pattern occurred within only two months. In terms of moving cost and dietary quality,Yakushima macaques shifted their foraging pattern according to the availability of M. rubrafrom a “low-cost, low-yield” strategy to a “low-cost, high-yield” strategy, and then to a more costly strategy. The ability
to make such rapid shifts in foraging pattern may allow the macaques to effectively use the highly variable food supply within
their small range. 相似文献
110.
Martin Sprung 《Hydrobiologia》1995,304(2):117-132
Shell growth of tagged zebra mussels (Dreissena polymorpha) was monitored in lakes at 3 sites over 1 1/2 years. It varied greatly with the season and was almost absent during winter
months. Shell growth was significantly correlated with seston concentration, but not with water temperature. The theoretical
maximum size (L∞) of the v. Bertalanffy growth equation did not vary seasonally.
Tissue weight underwent a pronounced seasonal cycle. In animals of 20 mm shell length, minimum weights recorded in September
only corresponded to one quarter to one third of the maxima in late spring. Tissue weight of animals from the 3 sites was
distinctly different.
Carbohydrate content of the tissue stayed below 10 per cent and tended to be highest in spring. Spring maxima of lipids were
very pronounced. These lipids were primarily located in the digestive gland.
These data were combined with data of gonad size by Borcherding (1991). Results imply that production of reproductive tissue
even continues at a retarded rate during winter months, if food conditions were favourable. With poor food conditions, no
production of reproductive tissue was estimated during winter; this, however, was followed by an elevated rate of reproductive
tissue production in spring. Weight specific production decreased with a weight exponent of −0.24. Shell and byssus production
contributed only in the range of 10 per cent to total production.
Reproductive effort showed maxima of 30 to 45%. It increased with shell length at 2 sites and decreased at the other site
with the largest animals. 相似文献