Endocrine regulation of carbohydrate metabolism during the moult cycle in crustaceans I. Effect of eyestalk removal in Ocypoda platytarsis

The endocrine regulation of carbohydrate metabolism in the decapod Ocypoda platytarsis was investigated by eyestalk ablation at all stages of the moult cycle. Eyestalk removal (and hence removal of a substance probably produced by it) profoundly influences the carbohydrate level of the major storage organ, the hepatopancreas. The changes taking place storage organ, the hepatopancreas. The changes taking place in hepatopancreatic glycogen are reflected in the blood sugar (glycemic) level. The blood-sugar level is also related to dynamic events taking place in the cuticle during the moult cycle. At the intermoult and postmoult stages, the eyestalk factor directs the sugar supply for energy metabolism, and prevents sugar deposition as glycogen in the hepatopancreas. At the premoult stage, the activity of the eyestalk is suppressed by the moulting gland (the Y organ), as eyestalk ablation does not alter the blood-sugar value or the hepatopancreatic glycogen-level. After the increase at the freshmoult stage due to eyestalk ablation, the blood-sugar level tends to re-attain its previous low level at the postmoult stage.     

Carbohydrate metabolism of two crustaceans during starvation

In Emerita asiatica and Ligia exotica, starvation for 1 week steadily depleted the free sugar values, indicating their involvement in nutritive physiology. Protein-bound blood sugars showed no change during starvation, indicating their non-involvement in general carbohydrate metabolism; it is suggested that they may be involved in the moulting physiology related to the synthesis of structural components such as chitin. The extent of glycogen storage is found to be greater in the anomuran E. asiatica than in the isopod L. exotica. In the latter, the fall in free sugar values during starvation is greater, due to meagre storage of glycogen in the hepatopancreas. these features are related to habitat and availability of food in the environment.     

Glycogen storage in relation to the moult cycle in the two crustaceansEmerita asiatica andLigia exotica

InEmerita asiatica, the quantitative fluctuations in the glycogen content of the hepatopancreas were markedly related to the moult cycle. The glycogen content of the hepatopancreas was maximum during premoult stages. It has been suggested that reserve glycogen, in addition to meeting general metabolic needs, may be especially involved in the genesis of the sugar precursors of chitin. The marked fall in the hepatopancreas glycogen values following moulting is probably due to its utilization in chitin synthesis during and immediately following moulting. InE. asiatica, the storage of glycogen was found to be meagre in muscles, and muscle glycogen had no bearing on chitin synthesis during moulting. InLigia exotica, glycogen is stored to a lesser extent than inE. asiatica, and was found in connective tissue and muscles. Significant fluctuations were noted in glycogen values correlated with the phases in the moult cycle when chitin synthesis took place. InL. exotica, the hepatopancreas does not serve as a storage depot for glycogen related to chitin synthesis.     

Effect of Heavy Metals on the Blood Protein Biochemistry of the Fish CYPRINUS CARPIO AND ITS USE AS A BIO-INDICATOR OF POLLUTION STRESS

Cyprinus carpio were exposed to two non-essential (Hg and Pb)and two essential (Cu and Ni) heavy metal salts at lethal andsub-lethal concentrations. Blood serum total protein, serum globulinand serum albumin was analysed every 2 hr for 24 hrs andagain at 48 and 72 hrs. Serum protein and globulin level showedan intial sharp increase from 2 to 20 hrs, followed by decline thatextend over a period of 72 hrs. Serum albumin showed an initialimmediate decline from 2 to 4 hrs, followed by an intermittent period of recovery and decline that extend over a period of 72hrs. Both lethal and sub-lethal concentrations of metal salts elicited asimilar pattern of response varying only in magnitude. The use offish blood serum protein, albumin and globulin measurements as general indicators of pollutant stress response isdiscussed.     

Do frogs really eat cardamom? Understanding the myth of crop damage by amphibians in the Western Ghats,India

In the Western Ghats of India, amphibians are culled at cardamom plantations since they are perceived to consume cardamom. To better understand the relationship between amphibians and cardamom, a study was undertaken at these plantations, which harbor numerous threatened and range-restricted amphibians. We undertook questionnaire surveys with 298 respondents at 148 plantations across southern India. Time-activity budget and diet analysis surveys were undertaken to determine whether amphibians really consumed cardamom. The conception that amphibians eat cardamom was found to be widespread especially among small-sized plantations, leading to negative perceptions and a lack of interest in amphibian conservation. The plantation community perceives a substantial economic loss due to amphibians, even though this is non-existent as revealed by our field surveys. These perceptions would lead to a continued intolerance of amphibian presence in plantations. A suitable outreach initiative re-affirming facts and spreading awareness on the positive role of amphibians would need to be conducted to negate this age-old myth.     

Effect of start of main injection timing on performance,emission, and combustion characteristics of a VGT CI engine fueled with neem biodiesel

The performance of engine parameters is more influenced with fuel injection strategies namely start of main injection timing (SoMI). An experimental analysis was performed to find the optimum SoMI timing based on performance, emission, and combustion characteristics. Base fuel of diesel and neem biodiesel was used as test fuels. The neem biodiesel was prepared by esterification and transesterification process. It is found from literature that neem biodiesel blend NB20 with diesel gives optimum performance and emission characteristics; therefore, NB20 blend was used for experiments. A variable geometry turbocharger (VGT) compression ignition (CI) engine was used to conduct the experiments. Engine performance parameters were estimated and compared with a base fuel of diesel and with NB20 blends. In this experimentation, fuel injection pressure (FIP) of 800 bar and engine speed of 1700 rpm were considered. SoMI timing was varied from 2° to 10° bTDC with an increment of 2° bTDC timing. Cylinder pressure (CP) and heat release rate (HRR) were estimated and found that are higher for diesel fuel compared to NB20 blend at different SoMI timings. The addition of neem biodiesel NB20 blend to diesel fuel decreases the exhaust emissions except NOx emissions. The BSFC was considerably reduced and BTE was improved almost equivalent to the diesel fuel for NB20. From the results, it is concluded that 10° bTDC SoMI timing provides 13% improvement in BTE, 21% decrement in BSFC, and 7.5% reduction in CO₂ emissions.

     

Blood sugars in relation to chitin synthesis during cuticle formation in Emerita asiatica

Blood sugars of the crustacean Emerita asiatica were studied during the moult cycle to examine their possible role in the synthesis of chitin, which takes place at the time of moulting. Blood sugars occur both in free state as well as bound with proteins, and show quantitative fluctuations in different phases of the moult cycle. The values of sugars were estimated in relation to total blood volume, to obviate the effects o absorption of water and consequent dilution of blood taking place during moulting. The data obtained suggest that the presence of glucosamine only during premoult stage may be due to resorption of chitin preparatory to the shedding of the cuticle. The fluctuations in the protein-bound blood sugars appear significant in the context of the synthesis of chitin, in view of the correlation seen between these and the chitin content. The above suggestion is supported by the observation that they are not involved in the nutritive metabolism of the crustacean. The protein-bound sugars do not appear to undergo further changes in the blood, as may be inferred by the absence of uridine diphosphate, and uridine diphosphate acetylglucosamine compounds, which have been suggested to be the more immediate precursors of chitin during the moult cycle of insects. It is suggested that protein-bound sugars may be transported, as such, to the epidermis, which may be the site of the final steps in chitin synthesis.     

A review of emerging technologies for remediation of PFASs

The need for remediation of poly‐ and perfluoroalkyl substances (PFASs) is growing as a result of more regulatory attention to this new class of contaminants with diminishing water quality standards being promulgated, commonly in the parts per trillion range. PFASs comprise >3,000 individual compounds, but the focus of analyses and regulations has generally been PFASs termed perfluoroalkyl acids (PFAAs), which are all extremely persistent, can be highly mobile, and are increasingly being reported to bioaccumulate, with understanding of their toxicology evolving. However, there are thousands of polyfluorinated “PFAA precursors”, which can transform in the environment and in higher organisms to create PFAAs as persistent daughter products. Some PFASs can travel miles from their point of release, as they are mobile and persistent, potentially creating large plumes. The use of a conceptual site model (CSM) to define risks posed by specific PFASs to potential receptors is considered essential. Granular activated carbon (GAC) is commonly used as part of interim remedial measures to treat PFASs present in water. Many alternative treatment technologies are being adapted for PFASs or ingenious solutions developed. The diversity of PFASs commonly associated with use of multiple PFASs in commercial products is not commonly assessed. Remedial technologies, which are adsorptive or destructive, are considered for both soils and waters with challenges to their commercial application outlined. Biological approaches to treat PFASs report biotransformation which creates persistent PFAAs, no PFASs can biodegrade. Water treatment technologies applied ex situ could be used in a treatment train approach, for example, to concentrate PFASs and then destroy them on‐site. Dynamic groundwater recirculation can greatly enhance contaminant mass removal via groundwater pumping. This review of technologies for remediation of PFASs describes that:

• GAC may be effective for removal of long‐chain PFAAs, but does not perform well on short‐chain PFAAs and its use for removal of precursors is reported to be less effective;
• Anion‐exchange resins can remove a wider array of long‐ and short‐chain PFAAs, but struggle to treat the shortest chain PFAAs and removal of most PFAA precursors has not been evaluated;
• Ozofractionation has been applied for PFASs at full scale and shown to be effective for removal of total PFASs;
• Chemical oxidation has been demonstrated to be potentially applicable for some PFAAs, but when applied in situ there is concern over the formation of shorter chain PFAAs and ongoing rebound from sorbed precursors;
• Electrochemical oxidation is evolving as a destructive technology for many PFASs, but can create undesirable by‐products such as perchlorate and bromate;
• Sonolysis has been demonstrated as a potential destructive technology in the laboratory but there are significant challenges when considering scale up;
• Soils stabilization approaches are evolving and have been used at full scale but performance need to be assessed using appropriate testing regimes;
• Thermal technologies to treat PFAS‐impacted soils show promise but elevated temperatures (potentially >500 °C) may be required for treatment.

There are a plethora of technologies evolving to manage PFASs but development is in its early stage, so there are opportunities for much ingenuity.     

Blood sugar metabolism during moulting in the isopod crustacean Ligia exotica

Blood sugar metabolism of the isopod Ligia exotica Roux was studied in relation to chitin synthesis during the moult cycle. The blood sugars were found to occur free, as well as bound with blood proteins, during all moult stages, as in Emerita asiatica. The variety of free blood sugars is smaller in L. exotica; it comprises only glucose and glucose-6-phosphate. The protein-bound blood sugars are glucose and glucosamine. The blood-volume values do not differ markedly during the moult cycle. Estimations of blood sugars showed a marked rise of sugar levels in the blood during the premoult phase, and a subsequent fall during the freshmoult phase, when chitin is actively synthesised. The chitin values also showed a definite correlation with the blood-sugar values. The increased resorption of chitin during the premoult stage, and its liberation into the blood stream as glucosamine, is indicative of its reutilisation in chitin synthesis as in E. asiatica and the genus Cecropia. As more immediate precursors of chitin, such as uridine diphosphate and uridine diphophate acetylglucosamine compounds, were absent in the blood, a thorough biochemical study of the epidermis is suggested to locate the intermediate precursors of chitin which are possibly derived from blood sugars.     

Effects of radiation exposure on brain health: a state of the art and new challenges

Environmental Science and Pollution Research - Good brain health refers to a condition in which a person may fully realize their talents and improve their psychological, emotional, cognitive, and...