Ecophysiology of iron homeostasis in plants

In nature, iron (Fe) occurs in abundance and ranks fourth among all elements on Earth’s surface. Still, its availability to plants is reduced, once this element is in the form of hydrated oxides, which can limit plant productivity and biomass production. On the other hand, in high concentrations, this essential micronutrient for the plants can become a toxic agent, increasing the environmental contamination. Fe is necessary for the maintenance of essential processes like respiration and photosynthesis, participating in the electron transport chain and in the conversion between Fe²⁺ and Fe³⁺, being a key element for carbon dioxide (CO₂) fixation and, therefore, important for crop production of cultivated or natural species. The balance of Fe should be strictly controlled, because both its deficiency and its toxicity affect the physiological process of plants. In aerated soils Fe is present in the form of Fe³⁺, which is the oxidized form and is less available to plants, so these organisms have developed different strategies for absorption, transport and storage of Fe. Deficiency and excess of Fe correlate with local soil conditions and with the care adopted in plant nutrition during the phenological phases and/or in the course of its cultivation. In situations of excessive accumulation of Fe in tissues, an enhancement of hydroxyl radical generation (OH^?) occurs by Fenton reaction. Here, we review the nutritional, genetic and ecophysiological aspects of uptake, translocation and accumulation of Fe ions in plants growing under conditions of deficiency or toxicity of this metal.     

Thermal time requirements of root-knot nematodes on zucchini-squash and population dynamics with associated yield losses on spring and autumn cropping cycles

The present research was undertaken to evaluate the effects of soil temperature on the life cycle of root-knot nematodes (RKN) on zucchini-squash in growth chambers and to assess the relationship between Meloidogyne incognita soil population densities at planting (Pi), its multiplication rate, and crop losses of zucchini in field conditions. Thermal requirements for M. incognita and M. javanica were determined by cultivating zucchini plants in pots inoculated with 200 second stage juveniles (J2) of each Meloidogyne species at constant temperatures of 17, 21, 25, and 28 °C. Number of days from nematode inoculation until appearance of egg laying females and until egg hatching were separately recorded. For life cycle completion, base temperatures (Tb) of 12?ºC and 10.8?ºC and accumulated degree-days above Tb (S) of 456 and 526, were estimated for M. incognita and M. javanica, respectively. The relationship between fruit weight and M. incognita Pi fits the Seinhorst damage function, but differed accordingly to the cropping season, spring or autumn. Tolerance limits for M. incognita on zucchini were 8.1 J2 per 250 cm³ of soil in spring and 1.5 in autumn cropping cycles, and the minimum relative yields were 0.61 in spring and 0.69 in autumn. Zucchini-squash was a poorer host for M. incognita in spring than in autumn, since maximum multiplication rates (a) and equilibrium densities (E) were lower in spring (a?=?16–96; E?=?274–484) than in autumn (a?=?270–2307; E?=?787–1227).     

Glyphosate- and imazethapyr-induced effects on yield, nodule mass and biological nitrogen fixation in field-grown glyphosate-resistant soybean

Over half of the 21 Mha of soybean planted in Brazil is now transgenic glyphosate-resistant (GM_RR). A field experiment was carried out to investigate whether the application of glyphosate or imazethapyr to the GM_RR variety reduced the input of N₂ fixation (BNF). No effects on yield, total N accumulation, nodulation and BNF (δ¹⁵N) could be assigned to the genetic modification of the plant. Imazethapyr reduced soybean yield but had no significant effect on BNF. Even though yields were not affected by glyphosate, the significant reduction of nodule mass and BNF to the GM_RR suggests that the use of this herbicide could lead to an increased dependence on soil N and consequently an eventual decrease of SOM reserves.     

Nutraceutic effect of free condensed tannins of <Emphasis Type="Italic">Lysiloma acapulcensis</Emphasis> (Kunth) benth on parasite infection and performance of Pelibuey sheep

Forty-five Pelibuey sheep were experimentally infested with nematodes to evaluate the effect of three free condensed tannin (FCT) levels of Lysiloma acapulcensis on fecal egg counts (FECs), packed cell volumes (PCV), ocular mucosa colors (OMC), average daily gain (ADG), and adult nematode count. Five treatments were used: 12.5, 25.0, and 37.5 mg of FCT kg^?1 of body weight (BW); sterile water (control); and ivermectine (0.22 mg kg^?1 of BW) as chemical group. The data were processed through repeated measurement analysis. Even though the three FCT doses decreased (P?<?0.05) the FEC, the highest reduction was obtained with 37.5 mg kg^?1 of BW. No differences were observed in PCV and OMC. Higher ADG (P?<?0.05) was observed with 37.5 mg kg^?1 of BW of FCT. The count of adult nematodes (females and males) in the higher dose of FCT was similar to chemical treatment. Dose of 37.5 mg kg^?1 of BW decreased the parasite infection and improved the lamb performance. Therefore, this dose could be used as a nutraceutic product in sheep production.     

Reproductive outcomes of anestrous goats supplemented with spineless Opuntia megacantha Salm-Dyck protein-enriched cladodes and exposed to the male effect

Tropical Animal Health and Production - The possible influence of the “male effect” upon reproductive outcomes of adult anestrous goats under marginal rangeland conditions and...     

Bupivacaine 0.25% and methylene blue spread with epidural anesthesia in dog

ObjectiveTo evaluate the extent sensory and motor blocks produced by the epidural injection of different volumes of 0.25% bupivacaine (Bu) with methylene blue (MB), in dogs.Study designProspective experimental trial.AnimalsTwenty healthy adult mongrel dogs, weighing 9.9 ± 1.9 kg.MethodsDogs were randomly allocated into one of four groups that received 0.2, 0.4, 0.6 or 0.8 mL kg^?1 of an epidural solution containing 0.25% Bu and MB. Sensory block was evaluated against time by pinching the tail, hind limb interdigital web, toenail bases and the skin over the vertebral dermatomes. Motor block was assessed by ataxia, hind limb weight-bearing ability and by loss of muscle tone of the tail and pelvic limbs. Data were collected at 2, 5, 10, 15 and 30 minutes after the end of epidural injection. After the final time point, dogs were euthanatized and laminectomies were conducted to expose the extent of the dural dye staining.ResultsThe volumes 0.2, 0.4, 0.6 and 0.8 mL kg^?1 of 0.25% Bu and MB blocked a mean of 5, 14.2, 20.2 and 21 dermatomes, respectively. The extent of the senory block increased up to a volume of 0.6 mL kg^?1. Motor block was longer-lasting and more intense than sensory block. Complete dyeing of the spinal cord with MB was achieved in some dogs at 0.4 mL kg^?1 and all dogs at 0.6 mL kg^?1.ConclusionsThe volume of anesthetic injected into the epidural space plays an important role in the quality of the epidural anesthesia. At 0.25%, bupivacaine provided an efficient sensory block at 0.6 mL kg^?1.Clinical relevanceRelatively high volumes (0.6 mL kg^?1) of 0.25%, BU and MB were needed to produce an effective sensory and motor block caudal to the umbilicus, but all spinal cord segments were reached by MB at this dose.     

Characterization of Phytophthora infestans populations of southern Brazil in 2004 and 2005

The populations of Phytophthora infestans (Pi) in southern Brazil in 2004 and 2005 are characterized herein. The isolates were collected from potato and tomato plants in the states of Paraná (PR), Santa Catarina (SC), and Rio Grande do Sul (RS). The mating type of 131 potato and 32 tomato isolates was determined. Forty-nine isolates from potatoes and 11 from tomatoes were analyzed for their Gpi phenotype. A subset of 35 isolates was evaluated for mitochondrial (mtDNA) polymorphisms. A sample of 146 isolates was tested for sensitivity to the fungicide metalaxyl, and most isolates (64%) were moderately sensitive. Fifty-nine isolates were classified as A1 mating type and 103 as A2. One isolate behaved as both A1 and A2 mating type. All tomato isolates were A1 mating type and presented the 86/100 pattern for the enzyme GPI and mtDNA Ib, indicating that these isolates belong to the US-1 clonal lineage. Of the 131 potato isolates, 103 were A2, 27 were A1 and one was A1/A2 mating type. Among the potato isolates 27 exhibited the Gpi phenotype 100/100, the same as BR-1, and 20 were 86/100, the same as US-1. Potato isolates presented the mitochondrial haplotypes Ia (74%) and IIa (26%). The data suggest the presence of only the BR-1 clonal lineage on potatoes in the states of PR and SC. However, in the state of RS, more than one clonal lineage was observed infecting potatoes, and there may be sexual reproduction between the lineages.     

The use of melatonin and progestagen–eCG to initiate reproductive activity in prepuberal Awassi ewe lambs

This experiment was conducted to evaluate the effect of administering hormonal treatments (melatonin and progestagen/equine chronic gonadotropin (eCG)) on advancing puberty in Awassi ewe lambs. Fifty-one 6-month-old ewe lambs of similar body weights (around 28 kg) were randomly assigned into four treatment groups; control (CON; n?=?14), melatonin (MEL; n?=?13), melatonin plus progestagen–eCG (MELPP; n?=?11), and progestagen–eCG (PP; n?=?13). Ewe lambs in the PP and MELPP groups were fitted with intravaginal progestagen sponges containing 60 mg medroxyprogesterone acetate for 14 days; 400 IU eCG were administered to each of these ewe lambs on the day of sponge removal. Ewe lambs in the MEL and MELPP groups received subcutaneous melatonin implants (Regulin®, 18 mg melatonin) 36 days before sponge insertion. Hormonal treatment had no effect on ewe lamb body weight change. Estrous behavior was greater (p?p?p?p?相似文献