Loss of function mutations at the tomato SSI2 locus impair plant growth and development by altering the fatty acid desaturation pathway.

The stearoyl-ACP desaturase (SACPD) is a key enzyme in the regulation of saturated to unsaturated fatty acid ratio, playing a crucial role in regulating membrane stability and fluidity, as well as photosynthesis efficiency, which makes it an important research focus in crop species. This study reports the characterization and molecular cloning of pale dwarf (pad), a new tomato (Solanum lycopersicum L.) T-DNA recessive mutant, which exhibits a dwarf and chlorotic phenotype. Functional studies of the T-DNA tagged gene were conducted, including phylogenetic analysis, expression and metabolomic analyses, and generation of CRISPR/Cas9 knockout lines. The cloning of T-DNA flanking genomic sequences and a co-segregation analysis found the pad phenotype was caused by a T-DNA insertion disrupting the tomato homologue of the Arabidopsis SUPPRESSOR OF SALICYLIC ACID INSENSITIVITY 2 (SlSSI2), encoding a plastid localized isoform of SACPD. The phenotype of CRISPR/Cas9 SlSSI2 knockout lines confirmed that the morphological abnormalities in pad plants were due to SlSSI2 loss of function. Functional, metabolomic and expression analyses proved that SlSSI2 disruption causes deficiencies in 18:1 fatty acid desaturation and leads to diminished jasmonic acid (JA) content and increased salicylic acid (SA) levels. Overall, these results proved that SSI2 plays a crucial role in the regulation of polyunsaturated fatty acid profiles in tomato, and revealed that SlSSI2 loss of function results in an inhibited JA-responsive signalling pathway and a constitutively activated SA-mediated defence signalling response. This study lays the foundation for further research on tomato SACPDs and their role in plant performance and fitness.

Digestive utilization of goat and cow milk fat in malabsorption syndrome.

We studied the effects of goat and cow milk fat on the digestive utilization of this nutrient and on some of the biochemical parameters that are related to the metabolisim of lipids, using rats with a resection of 50% of the distal small intestine and control animals (transected). The fat content in all the diets was 10% but the lipid quality was varied: the standard diet was based on olive oil, while the other two diets included fat obtained from lyophilized goat milk and cow milk, respectively. The digestive utilization of the fat was lower in the resected animals than in the transected ones for all three diets studied. In both resected and transected animals. the apparent digestibility coefficient (ADC) of the fat was greater with the standard diet (olive oil) than with diets whose fat content was provided by goat or cow milk. The digestive utilization of the fat was greater in the transected and resected rats receiving a diet of goat's milk (rich in medium-chain triglycerides) than those given a cow-milk-based diet and more closely approached the values obtained for olive oil. The consumption of goat milk reduced levels of cholesterol while levels of triglycerides, HDL, GOT and GPT remained with in the normal ranges, for both transected and resected animals. The advantageous effect of goat milk on the metabolisim of lipids with respect to cow milk suggests that the former should be included in the diet in eases of malabsorption snydrome.

Beneficial effect of pollen and/or propolis on the metabolism of iron, calcium, phosphorus, and magnesium in rats with nutritional ferropenic anemia.

There has been considerable debate regarding the nutritional benefits of pollen and the propolis produced by bees, although most contributions have lacked scientific soundness. This paper describes the possible beneficial effect of their use in pharmacological products in cases of anemic syndrome. We studied the effect of these two natural products on the digestive utilization of iron, calcium, phosphorus, and magnesium, using control rats and rats with nutritional ferropenic anemia. The addition of these products to the diet produced a positive effect on weight gain; this fact could constitute a scientific basis for the application of pollen and propolis as fortifiers. They improve the digestive utilization of iron and the regeneration efficiency of hemoglobin, especially during recovery from an anemic syndrome. They also have a positive effect on phosphocalcic metabolism and maintain an appropiate level of magnesium metabolism. Furthermore, in iron-deficient rats, these natural products palliate, to a large extent, the adverse effects of iron deficiency on calcium and magnesium metabolism as a result of the improvement in the digestive utilization of these minerals.

Influence of goat and cow milk on the digestive and metabolic utilization of calcium and iron.

The effects of goat and cow milk on the digestive and metabolic utilization of calcium and iron were studied in rats using a standard (non-milk) control diet. The digestive utilization of calcium is greater when the animals consume the goat-milk-based diet rather than that based on cow milk or the standard diet. The digestive utilization of iron, however, is similar for the goat-milk diet and the standard diet, and in both cases superior to that based on cow milk. The calcium content in the femur, sternum and Longissimus dorsi muscle (L.D. muscle) provides an indication of what happens during the utilization of the mineral; more is deposited when the rats consume a milk-based diet, particularly one based on goat milk. The iron content in the reserve organs, namely the liver and the spleen, is greater with the standard diet and the goat milk diet than with that containing cow milk. There is an obviously beneficial effect of goat milk on the metabolism of calcium and iron, which minimizes any interaction between the two minerals.

The importance of the proportion of heme/nonheme iron in the diet to minimize the interference with calcium, phosphorus, and magnesium metabolism on recovery from nutritional ferropenic anemia.

The digestive utilization of Fe and its nutritive interaction with Ca, P, and Mg were studied in rats with nutritional ferropenic anemia. The diet contained 80% ferric citrate and 20% heme iron (80/20 diet). The weight gain, digestive utilization of Fe, and regeneration efficiency of hemoglobin and seric Fe were higher in iron-deficient rats (ID) fed the 80/20 diet than in iron-deficient rats fed the 50/50 diet (Campos et al., 1996). The phospho-calcic metabolism, which is adversely affected in ferropenic anemia, returned to normal values when iron was added to the diet. The digestive utilization of Mg, which fell with the 50/50 diet (Campos et al., 1996), returned to normal values when the ferropenic anemia was reversed with the 80/20 diet. In a state of iron deficiency, certain parameters related to the glucose and lipid metabolism are affected; the glucose and triglycerides values return to a normal range with the 80/20 diet.

Interactions among iron, calcium, phosphorus and magnesium in the nutritionally iron-deficient rat.

We studied the development of nutritional iron deficiency 0, 10, 20, 30 and 40 days after the intake of a semisynthetic diet lacking iron (diet 0) and the possible interactions with calcium, phosphorus and magnesium in both control rats and rats after 40 days of iron deficiency. During this period, iron deficiency was found to produce stress in the rats, as evidenced by high levels of cortisol in the serum. High levels of parathyroid hormone (PTH) were also found. There was a considerable increase in the absorption of calcium, phosphorus and magnesium, but the phosphorus and magnesium balance decreased and that of calcium remained practically unchanged, although there was an increase in calcium urinary elimination. Despite the noticeable degree of bone demineralization, which was evident in the femur, serum levels of calcium, phosphorus and magnesium remained constant. The present study shows that severe nutritional ferropenic anaemia provokes significant alterations in the metabolism of calcium, phosphorus and magnesium. We conclude that these alterations should be taken into account in the treatment of this pathology, given its prevalence and the fact that it may exacerbate other pathologies, particularly those related to the metabolism of calcium and phosphorus.

Influence of nutritional iron deficiency development on some aspects of iron, copper and zinc metabolism.

This paper examines the development of iron (Fe) deficiency and its possible interactions with trace elements such as zinc (Zn) and copper (Cu) by investigating iron-deficient and control rats. The effects of iron deficiency were studied at day 0, 10, 20, 30 and 40 in rats fed on an iron-free diet (diet ID). It was found that the critical period in the development of nutritional iron deficiency occurs after 30 to 40 days without iron supplementation. At this time the organism is unable to maintain haemoglobin levels without endangering the iron-dependent enzymatic groups which are essential for life. It was also demonstrated that in a situation of iron deficiency, there occurs a greater absorption of copper, while that of zinc remains unchanged. As iron deficiency progresses, the levels of copper in the spleen and the sternum increase. It is apparent that iron deficiency provokes more marked alterations in the metabolism of copper than of zinc.

Iron-manganese interactions in the evolution of iron deficiency.

This article examines the evolution of nutritional iron deficiency and the possible interactions with other minerals, such as manganese, in control and iron-deficient rats. The evolution of iron deficiency was studied at 0, 10, 20, 30 and 40 days of providing the animals with an iron-free diet (diet 0). It was found that the critical period in the development of nutritional iron deficiency occurs after 30-40 days without iron, at which moment the organism is unable to maintain hemoglobin levels without endangering the iron-dependent enzymatic groups which, in turn, are essential for life. It was also demonstrated that in a situation of iron deficiency, there occurs a greater absorption of manganese. It should be noted that this greater absorption of manganese is not reflected in the concentration of the mineral in the organs. Therefore, it is evident that the interactions of iron with manganese take place at the digestive level with no apparent consequences being observed at the metabolic level.

The absorption of iron, calcium, phosphorus, magnesium, copper and zinc in the jejunum-ileum of control and iron-deficient rats.

The effects of iron deficiency on the absorption of different dietary sources of iron were studied, together with the interactions between iron, calcium, phosphorus, magnesium, copper and zinc in the jejunum-ileum of control and iron-deficient rats. In this study, three perfusion solutions containing different iron sources: ferric citrate, haemoglobin, and equal parts of ferric citrate and haemoglobin were used. In addition, the same perfusion solutions were used with and without 2,4-dinitrophenol, an inhibitor of oxidative phosphorylation. Iron absorption in anaemic rats was greater than in the controls, except after perfusion with solutions containing haemoglobin. The absorption of calcium, copper and zinc in iron-deficient animals was not significantly affected, while the absorption of phosphorus and magnesium increased, with respect to animals in the control group. After perfusion with solutions containing haemoglobin, the absorption values of calcium, copper and zinc were lower than after ferric citrate in both groups (control and iron-deficient rats).

Effect of source of iron on duodenal absorption of iron, calcium, phosphorous, magnesium, copper and zinc in rats with ferropoenic anaemia.

We studied the effects of iron deficiency on the in vivo absorption (by using the intestinal perfusion technique in the duodenum) of different dietary sources of iron (haem, non-haem and equal parts of both forms) and investigated the interactions between iron and calcium, phosphorous, magnesium, copper and zinc in control and iron-deficient rats. Three perfusion solutions containing a different source of iron were used: solution 1, ferric citrate; solution 2, haemoglobin; solution 3, equal parts of ferric citrate and haemoglobin. We also tested the same perfusion solution with 2,4-dinitrophenol (2,4-DNP), an inhibitor or oxidative phosphorylation (solutions 1-I, 2-I and 3-I). In control rats we observed three mechanisms of iron absorption: passive for soluble iron salts, active receptor-mediated for non-haem iron complexes, and active receptor-mediated for haem iron. In anaemic rats iron absorption was greater than in controls, except after perfusion with solution 2 (containing haemoglobin). Absorption increased as a result of both the passive and active, receptor-mediated mechanism for non-haem iron complexes. The active component was influenced by the depletion of haem receptors under severe iron deficiency. The absorption of calcium, copper and zinc in iron-deficient animals was lower than in controls, whereas phosphorus and magnesium absorption were not significantly affected. After perfusion with solution 2 or 3, calcium, copper and zinc absorption were lower than after solution 1. We conclude that ferropoenic anaemia in the rat impairs the absorptive process of those minerals that are absorbed, at the duodenal level mainly via active transport (haem iron, calcium, copper and zinc), but does not affect the active component involved in non-haem iron absorption.

Calcium absorption in rats with distal intestinal resection: influence of type of dietary fat, cholecalciferol and nature of the adaptative response.

The effects of dietary fat and supplementation with cholecalciferol on calcium absorption at different luminal concentrations (2.07 mmol/l and 2.07 mmol/l with 0.5 mmol/l 2,4-dinitrophenol and 8.20 mmol/l) were studied in vivo in the perfused duodenum, residual jejunum and proximal colon of rats with resection of 50% of the distal small intestine, as well as the nature of the adaptative response (passive or active). Changing the source of dietary fat (diet B, containing 1/3 medium chain triglycerides, 1/3 olive oil, 1/3 sunflower oil) increased calcium absorption, preferentially via active transport, in both transected and resected rats. Supplementation of diet B with cholecalciferol further enhanced intestinal calcium absorption, especially in the colon. These results suggest the importance of diet in the adaptive processes and confirm that active mechanisms of transport adapt more readily to intestinal resection than do passive mechanisms.

Effects of iron replenishment on iron, calcium, phosphorus and magnesium metabolism in iron-deficient rats.

We investigated the effect of Fe deficiency on the nutritive utilization of Fe, Ca, P and Mg in rats. Aside from the well known depletion of Fe in liver, femur and sternum with low values of Hb, Fe deficiency impaired Ca, P and Mg metabolism at different degrees. Iron deficiency altered Mg absorption, lowered the concentration of Ca in the liver, femur and sternum, raised the concentration of P and Mg in the liver, and decreased P in the femur. The altered status was not completely rectified by iron supplementation as the animals were still slightly anemic at the end of the study. The second purpose of the study was to evaluate the ability of three iron compounds (ferric citrate, ferrous sulfate and ferrous ascorbate) to correct the undesirable effects of Fe deficiency. Ten days after treatment with these diets, Fe-deficient rats still had reduced Mg absorption, especially those fed ferric citrate. The concentrations of hemoglobin approached normal values in all groups; however, serum Fe remained low, indicating that Fe reserves were still depleted. Hepatic and femoral Fe concentrations were also lower in all Fe-deficient groups regardless of the diet given, compared with their respective controls, whereas Fe concentrations in the sternum increased significantly with all three diets, suggesting an increase in erythropoiesis. The concentration of Ca, P and Mg in liver approached normal values, and appeared to normalize in the femur, except that Ca and P concentrations remained low with the citrate diet. In the sternum, a site assumed to have higher requirements for these minerals, the concentrations of Ca, P and Mg also increased. These findings indicate that Fe is involved in the bone mineralization, and that in physiological terms, Fe interacts favorably with Ca, P and Mg metabolism, since Fe deficiency altered the status of these metals. These findings also suggest that ferrous ascorbate and ferrous sulfate were more effectively absorbed than was ferric citrate.

Supplementation of a cereal-milk formula with haem iron palliates the adverse effects of iron deficiency on calcium and magnesium metabolism in rats.

Aside from the well known alteration of Fe status in Fe deficiency, this condition has also a negative effect on the bioavailability of Ca and Mg. We studied the influence of the supplementation of a commercial cereal-milk formula with bovine blood on Fe, Ca, P, and Mg metabolism in control and Fe-deficient rats to investigate whether high Fe levels in diet produce some interactions and the possibility of decreasing these latter by a haem-Fe supplementation. The bioavailability in control and Fe-deficient animals was determined as the apparent digestibility coefficient and hemoglobin regeneration efficiency, both of which are accurate estimations of total Fe utilization. Non-fortified cereal-milk formula decreased the apparent digestibility coefficient of Ca and Mg in Fe-deficient rats; the concentrations of these minerals in liver, femur, and sternum were lower than in control animals. However, when the Fe content of the cereal-milk formula was doubled by supplementation with bovine blood, the adverse effects on the digestive utilization of Ca, and especially of Mg, were palliated, the concentration of these two minerals in the organs investigated increased, and the overall Fe status improved in Fe-deficient rats.

Effects of intestinal resection, cholecalciferol and ascorbic acid on iron metabolism in rats.

The effect of dietary supplementation with ascorbic acid or cholecalciferol on Fe utilization was studied using the metabolic balance technique, in rats in which 50% of the distal small intestine was removed, or in which the mid small intestine was transected and reanastomosed (controls). Three different diets were used. The first (basal diet) contained (g/kg dry wt): protein (casein + 50 mg D,L-methionine/g) 120 and fat (medium-chain triacylglycerols, olive oil and sunflower oil, in equal parts) 40. The other diets were obtained by adding ascorbic acid (150 mg/kg diet) or cholecalciferol (0.4 mg/kg diet) to the basal diet. Apparent digestibility coefficient (ADC) and Fe retention were significantly lower in resected animals than in their respective control groups (transected rats). However, the addition of ascorbic acid or cholecalciferol to the basal diet increased the ADC and Fe retention in both transected and resected rats. Five weeks after surgery, resection also resulted in a reduced concentration of Fe in the sternum, but did not reduce the concentration of haemoglobin or serum Fe total Fe-binding capacity or the concentration of Fe in liver, testes, femur or muscle (longissimus dorsi). Supplementation with ascorbic acid increased serum Fe concentration, while the concentration of Fe in muscle was reduced by supplementation with both ascorbic acid and cholecalciferol. Neither supplementation had any effect on the Fe concentration in other tissues, on haemoglobin concentration or plasma total Fe-binding capacity. Thus, supplementation with ascorbic acid or with cholecalciferol increased Fe absorption and reduced the concentration of Fe in muscle.

Copper malabsorption after intestinal resection in rats. Effects of cholecalciferol and ascorbic acid.

Dietary modifications can partly compensate for the alterations in copper homeostasis caused by distal intestinal resection, by improving biliary function. We studied the effects of resecting 50% of the distal small intestine (DSI) on copper status in rats fed three semisynthetic diets (basal diet, and basal diet with cholecalciferol or ascorbic acid). Intestinal resection significantly decreased the digestive (apparent digestibility coefficient; ADC) and metabolic utilization (balance) of copper 1 month after surgery. However, the supplementation of the basal diet with cholecalciferol attenuated the negative impact of surgery, leading to small differences in Cu ADC and Cu balance between transected and resected rats. Ascorbic acid also enhanced copper retention. Copper status was not as markedly affected by intestinal resection as digestive utilization 1 month after the operation. The beneficial effects of cholecalciferol and ascorbic acid at the digestive and metabolic levels suggest ways to lessen the impact of intestinal resection, and to avoid possible long-term postabsorptive alterations in copper distribution.

Effects of type of dietary fat and cholecalciferol on magnesium absorption in rats with intestinal resection.

We studied the effect of type of dietary fat and supplementation with cholecalciferol on magnesium absorption in the duodenum, jejunum and proximal colon in rats with resection of 50% of the distal small intestine. Magnesium transport against the concentration gradient was found to occur in all three intestinal segments, although transport increased significantly only in the proximal colon of intestinally resected rats fed a diet supplemented with cholecalciferol at a rate of 0.425 mg/kg diet and mixture of equal parts of medium chain triglycerides, sunflower oil and olive oil as the source of dietary fat (diet B), in comparison with magnesium absorption in control rats subjected to intestinal transection and fed diet B, and in resected rats fed a diet without cholecalciferol supplementation and in which olive oil was the sole source of dietary fat (diet A). Magnesium absorption due to active and passive transport together, was greater in resected than in transected rats in all three intestinal segments, although the difference was significant only in the jejunum (the segment closest to the anastomosis), because of the greater increase in mucosal mass in resected animals. When the three intestinal segments were compared, magnesium absorption in favour of and against the concentration gradient in the proximal colon was significantly greater than in the duodenum or the jejunum, in resected and transected animals fed diet A or diet B. These findings show that the colon is the segment that most efficiently absorbs magnesium in rats with intestinal resection, especially when diet B is given.

Effect of intestinal resection, type of dietary fat and time on biliary lipid secretion in rats.

The effects of time and the type of dietary fat on biliary physiology in rats with 50% resection of the distal small intestine were investigated. The effects of ursodeoxycholic acid as an exogenous source of bile acid added to the diet were also studied. The fat composition of all diets was the same in quantitative terms (4%), and differed only in the type of lipid supplied: olive oil (diet A) or one-third medium chain triglycerides, one-third sunflower seed oil and one-third olive oil (diet B). In resected rats given diet A for 1 or 3 months, there was a decrease in biliary secretion of cholesterol and phospholipids, and in the lithogenic index, with respect to the control group. Resected rats fed diet B for 1 or 3 months showed increases in biliary secretion of cholesterol and phospholipids, and in the lithogenic index, in comparison with resected rats fed diet A. The addition of ursodeoxycholic acid to diet B led to the decoupling of bile acid and bile lipid secretion.

Influence of dietary fat components and intestinal resection on iron, zinc and copper metabolism in rats.

The effect of resecting 50% of the distal small intestine (DSI) on iron, zinc and copper nutritive utilization was studied in rats fed two different types of diet: a standard diet containing 4% olive oil (A) and a diet containing different sources of fat (1/3 olive oil, 1/3 sunflower oil and 1/3 medium chain triglycerides) (B). One month and 7 days after surgery, intestinal resection led to a deterioration in digestive (ADC) and metabolic (balance) utilization of iron, zinc and copper. To assess trace metal postresectional homeostasis, we also measured these mineral concentrations in whole blood, plasma and several organs (liver, femur, sternum, longissimus dorsi muscle and testes). Our findings showed no significant differences in iron, zinc and copper concentrations between the organs, suggesting that the observed decrease in digestive and metabolic efficiency of these minerals was not markedly reflected at the postabsorptive level, since the distribution of the trace elements in the whole organism remained unchanged. We conclude that one month and 7 days after this surgical intervention, adaptive mechanisms are well developed in resected rats fed a diet with an adequate mineral supplement.

Effect of iron deficiency on the digestive utilization of iron, phosphorus, calcium and magnesium in rats.

The influence of the source of dietary Fe (ferric citrate alone or mixed with bovine blood at a proportion of 1:1 (v/v)) on the digestive utilization of Fe, P, Ca and Mg, and on haemoglobin regeneration efficiency (HRE) was investigated in control and Fe-deficient rats. Diet A contained (by analysis) 43.5 mg Fe/kg diet (as ferric citrate), and diet B contained 44.3 mg Fe/kg diet (ferric citrate-bovine blood). In Fe-deficient rats fed on diet A or B the apparent digestibility coefficient (ADC) of Fe increased by 42.3 and 45.7% respectively. The ADC of Ca and Mg decreased significantly in Fe-deficient rats regardless of the source of dietary Fe. The HRE increased by 72.9% in Fe-deficient rats fed on diet A, and by 91.1% in Fe-deficient animals fed on diet B. In Fe-deficient rats fed on Fe for 10 d the values of haematological variables approached normality. However, serum Fe remained low, indicating that Fe reserves were still depleted. A deficient dietary supply of Fe for 30 d did not significantly modify the numbers of circulating leucocytes.

Influence of ileal resection, type of diet and ursodeoxycholic acid on biliary secretion in rats.

We studied the effects of the type of dietary fat and of ursodeoxycholic acid, an exogenous bile acid added to the diet, on bile physiology in rats with 50% resection of the distal small intestine. The amount of fat was the same (4%) in all diets assayed, which differed only in the type of fat, (olive oil in diet A, and 1/3 medium-chain triglycerides, 1/3 sunflower oil and 1/3 olive oil in diet B). The removal of 50% of the distal small intestine raised the de novo hepatic synthesis of bile acids with respect to controls, regardless of whether diet A or diet B was given. The addition to diet B of ursodeoxycholic acid decreased bile flow and osmotic activity of bile acid in resected rats and raised bile acid-independent bile flow in comparison to resected rats given diet B without ursodeoxycholic acid.