β-Endorphin like immunoreactivity of brain,pituitary gland and plasma of rats submitted to postnatal protein malnutrition: Effect of behavioral training

Wistar-derived rats were raised and maintained either on a normal- (25% casein) or on a low-protein (8% casein) diet until the age of 100 to 114 days. Both diets were isocaloric and contained an adequate supply of salts and vitamins. There were gross differences in body, brain and pituitary weight between the two groups. In addition, the brain and pituitary content of β-endorphin like immunoreactivity was lower in the protein malnourished rats, and three different forms of training (50 tone-footshock shuttle avoidance trials; 50 tones alone (habituation); 50 footshocks alone) caused a depletion of brain β-endorphin like immunoreactivity in the normal, but not in the malnourished rats. Footshock stimulation caused, in addition, a pituitary decrease and a plasma increase of β-endorphin like immunoreactivity, also restricted to the normal diet group. Performance in the habituation and in the shuttle avoidance tasks was similar in the two groups, despite the different responsiveness of their brain and pituitary β-endorphin systems to training and/or stimulation. In view of the possible involvement of these systems in learning suggested by these and by previous data, it seems likely that the neurohumoral regulation of habituation and avoidance learning may be different in rats submitted to protein malnutrition when compared to controls.     

Time of replication of genes responsible for a temperature-sensitive function in a cell cycle-specific ts mutant from a hamster cell line

A method involving short pulses of 5-bromodeoxyuridine (brUdRib) followed by irraidation with 313 nm light was used to locate the time of replication of certain genes during the cell cycle of two cell lines, AF8 and AL106. AF8, a temperature-sensitive mutant of BHK21/13 cells, grows at 33°C but not at 39.5°C. AL106, a hybrid clone of tsAF8 and SV-40 transformed Lesch-Nyhan fibroblasts (LNSV), which retains all hamster chromosomes and one human chromosome (No. 3), has the ability to grow at 39.5°C. AF8 and AL106 cells synchronized at the G₁-S boundary were released from their block and pulsed with brUdRib for 2-hour periods during the S phase. The cells were subsequently irradiated with 313 nm light. Colony-forming efficiency and revertants frequency were studied. Incorporation of brUdRib during the early S phase (0–4 hours from the begining of S), decreased the colony-forming efficiency of AL106 cells both at 33°C and 39.5°C, and also of AF8 cells at 33°C. No AF8 colonies grew at the nonpermissive temperature regardless of the treatment. Thus the time of replication of genes responsible for colony-forming ability was the same in tsAF8 at the permissive temperature and in AL106 at both temperatures. The time of replication of the genes responsible for the ts function in AF8 cells was located by determining the revertants frequency in synchronized AF8 cells pulsed with brUdRib and irradiated during 1- to 2-hour periods of the S phase. Back-mutants were scored by counting the number of clones capable of growing at 39.5°C (nonpermissive for AF8 cells). The highest frequency of induced back-mutations occurred in synchronized AF8 cells pulsed with brUdRib (and irradiated) between two to four hours from the begining of the S phase. Exposure to brUdRib during other periods of the S phase or during G₁ had no effect on the reversion rate. This method can be used to locate the time of replication (in S) of ts genes in other temperature-sensitive mutants or of other specific genes in other conditional mutants.     

Correlation of cotylenol with the aglycone of fusicoccin

The stereostructure of cotylenol, the aglycone of the cotylenins, has been confirmed by chemical correlation with the aglycone of fusicoccin A.     

The role of the IGF1 receptor in the regulation of cdc2 mRNA levels in fibroblasts

The levels of cdc2 mRNA increase when quiescent cells are stimulated by growth factors. In BALB/c 3T3, both platelet-derived growth factor and insulin-like growth factor 1 (IGF-1) are required to increase cdc2 mRNA levels. In p6 cells, which constitutively overexpress the IGF-1 receptor, IGF-1 is sufficient. The importance of the IGF-1/IGF-1 receptor interaction in regulating the levels of cdc2 mRNA was further confirmed by showing that an antisense oligodeoxynucleotide to the IGF-1 receptor RNA inhibited the IGF-1-mediated increase.     

Changes in RNA polymerase II in a cell cycle-specific temperature-sensitive mutant of hamster cells

tsAF8 cells are a temperature-sensitive mutant of BHK cells that arrest at the nonpermissive temperature in the G₁ phase of the cell cycle. The activity of solubilized RNA polymerase II and its ability to bind [³H]-γ-amanitin decrease in tsAF8 cells at 40.6°, with a half-life of ～ 10 hr. No appreciable changes occur in these two parameters in tsAF8 cells at 34° or in BHK cells at either 34° or 40.6°. Protein synthesis is not appreciably affected for at least 24 hr after tsAF8 cells are shifted to 40.6°. These results indicate that in tsAF8 cells at the nonpermissive temperature, there is a defect in either the synthesis, the assembly, or the stability of RNA polymerase II, and that the loss of RNA polymerase II molecules is not due to widespread cellular damage.     

Adenylyl cyclase deficient cr-1 (Crisp) mutant of Neurospora crassa: Cyclic AMP-dependent nutritional deficiencies

The inability to synthesize cyclic AMP drastically affects the nutritional metabolism of Neurospora crassa. The adenylyl cyclase-less mutant cr-1 (crisp) did not utilize several carbon sources, including glycerol, mannitol, arabinose, and casaminoacids. However, in glucose or acetate it grew as well as the wild type. The following evidence suggested that these nutritional deficiencies were a direct result of the cr-1 mutation: (i), in crosses to wild type they segregated together with the crisp morphological marker; (ii), cyclic AMP added to the cr-1 mutant growth medium overcame the nutritional deficiencies; (iii), the cyclic AMP effect was specific for the crisp mutant, for it was not observed with the wild type, nor with a spontaneous glycerol-utilizing cr-1 strain.     

Optimal control of the spatial allocation of COVID-19 vaccines: Italy as a case study

While campaigns of vaccination against SARS-CoV-2 are underway across the world, communities face the challenge of a fair and effective distribution of a limited supply of doses. Current vaccine allocation strategies are based on criteria such as age or risk. In the light of strong spatial heterogeneities in disease history and transmission, we explore spatial allocation strategies as a complement to existing approaches. Given the practical constraints and complex epidemiological dynamics, designing effective vaccination strategies at a country scale is an intricate task. We propose a novel optimal control framework to derive the best possible vaccine allocation for given disease transmission projections and constraints on vaccine supply and distribution logistics. As a proof-of-concept, we couple our framework with an existing spatially explicit compartmental COVID-19 model tailored to the Italian geographic and epidemiological context. We optimize the vaccine allocation on scenarios of unfolding disease transmission across the 107 provinces of Italy, from January to April 2021. For each scenario, the optimal solution significantly outperforms alternative strategies that prioritize provinces based on incidence, population distribution, or prevalence of susceptibles. Our results suggest that the complex interplay between the mobility network and the spatial heterogeneities implies highly non-trivial prioritization strategies for effective vaccination campaigns. Our work demonstrates the potential of optimal control for complex and heterogeneous epidemiological landscapes at country, and possibly global, scales.     

Biological nitrogen fixation and phosphate solubilization by bacteria isolated from tropical soils

Introduction

In addition to fixing atmospheric nitrogen, some bacterial isolates can also solubilize insoluble phosphates, further contributing to plant growth.

Aims

The objectives of this study were the following: isolate, select, and identify nodulating bacteria in the cowpea that are efficient not only in biological nitrogen fixation (BNF) but also in the solubilization of insoluble inorganic phosphates; identify and quantify the organic acids produced; and establish the relationship between those acids and the solubilizing capacity.

Methods

The bacteria were captured from two soils containing high concentrations of insoluble phosphorus from the cities of Lavras and Patos de Minas, using the cowpea [Vigna unguiculata (L.) Walp.] as bait. We obtained 78 strains, which were characterized according to their cultural attributes in culture medium 79 with the strains UFLA 03-84, INPA 03-11B, and BR3267 (approved by the Ministry of Livestock and Supply Agriculture—MAPA, as inoculants for the cowpea) and Burkholderia cepacia (LMG1222^T), which was used as a positive control for phosphate solubilization. Strains that were selected for their efficiency in both processes were identified by 16S rDNA sequence analysis. We evaluated the symbiotic efficiency (BNF) in a greenhouse and the solubilization efficiency of CaHPO₄, Al(H₂PO₄)₃, and FePO₄.2H₂O in solid and liquid GELP media. Strains that excelled at the solubilization of these phosphate sources were also evaluated for the production of the following organic acids: oxalic, citric, gluconic, lactic, succinic, and propionic.

Results

The presence of Acinetobacter, Bacillus, Firmicutes, Microbacterium, Paenibacillus, and Rhizobium was detected by 16S rDNA sequencing and analysis. Bacterial strains obtained from cowpea nodules varied greatly in the efficiency of their BNF and phosphate solubilization processes, especially in the strains UFLA 03-09, UFLA 03-10, UFLA 03-12, and UFLA 03-13, which were more efficient in both processes. More strains were able to solubilize insoluble inorganic calcium and iron phosphates in liquid medium than in solid medium. The production of organic acids was related to the solubilization of CaHPO₄ and FePO₄.2H₂O for some strains, and the type and concentration of the acid influenced this process.

Conclusions

These are the first results obtained with bacterial isolates from tropical soils in which the production of organic acids was detected and quantified to examine the solubilization of insoluble inorganic phosphates.     

Optimization of arsenic phytoremediation using Eichhornia crassipes

This study aimed to evaluate the pH, phosphate, and nitrate in the process of arsenic absorption by Eichhornia crassipes (water hyacinth), using the surface response methodology, in order to optimize the process. The plants were exposed to a concentration of arsenic of 0.5 mg L^?1 (NaAsO₂) over a period of 10 days. The results indicated optimal levels for the absorption of arsenic by E. crassipes at pH equal to 7.5, absence of phosphate, and minimum nitrate level of 0.0887 mmol L^?1. For the tested concentration, E. crassipes was able to accumulate 498.4 mg kg^?1 of As (dry base) in its plant tissue and to reduce 83% of the initial concentration present in the aqueous medium where it was cultivated. The concentration of phosphorus in solution linearly increased the phosphorus content in the plants and negatively influenced the absorption of arsenic. The concentration of 0.5 mg L^?1 of As did not significantly affect the relative growth rate (RGR) and the tolerance index (TI). 94% of As (III) initially solubilized in water was converted by the end of the experiment period into As (V). The water hyacinth was important in the phytoremediation of arsenic when cultivated under optimal conditions for its removal.