Alkali Damage Research Articles

Artificial humic acid promotes growth of maize seedling under alkali conditions

Salinization of cropland is one of the major abiotic stresses affecting global agricultural sustainability, posing a serious threat to agricultural productivity and food security. Application of artificial humic acid (A-HA) as plant biostimulants has been increasingly attracting farmers and researchers. However, its regulation of seed germination and growth under alkali stress has rarely received attention. The purpose of this study was to investigate the response of maize (Zea mays L.) seed germination and seedling growth after the addition of A-HA. The effects of A-HA on seed germination, seedling growth, chlorophyll contents and osmoregulation substance under black and saline soil conditions were studied by soaking maize in solutions with and without various concentrations of A-HA. Artificial humic acid treatments significantly increased the seed germination index and dry weight of seedlings. The effects of maize root in absence and presence of A-HA under alkali stress were also evaluated using transcriptome sequencing. GO and KEGG analyzes were performed on differentially expressed genes, and the reliability of transcriptome data was verified by qPCR analysis. Results showed that A-HA significantly activated phenylpropanoid biosynthesis, oxidative phosphorylation pathways and plant hormone signal transduction. Moreover, Transcription factor analysis revealed that A-HA induced the expression of several transcription factors under alkali stress which had a regulatory effect on the alleviation of alkali damage in the root system. Overall, our results suggested that soaking seeds with A-HA can alleviate alkali accumulation and toxicity in maize, constituting a simple and effective strategy to mitigate saline toxicity. These results will provide new insights for the application of A-HA in management to reduce alkali-caused crop loss.

PsnWRKY70 Negatively Regulates NaHCO3 Tolerance in Populus.

Poplar is an important afforestation and ornamental tree species in Northeast China. The distribution area of saline-alkali land is approximately 765 hm2 in Northeast China. The breeding of saline-alkali-resistant transgenic trees could be an effective method of afforestation in saline-alkali land. WRKY transcription factors play a crucial role in abiotic stress. In this study, we analyzed the genetic stability of the two-year-old PsnWRKY70 transgenic poplars. The results showed that PsnWRKY70 of transgenic poplars had been expressed stably and normally at the mRNA level. The gene interference expression (RE) lines had no significant effect on the growth of PsnWRKY70 under NaHCO3 stress, and the alkali damage index of RE lines was significantly lower than that of WT and overexpression (OE) lines at day 15 under NaHCO3 stress. POD activity was significantly higher in RE lines than in WT. The MDA content of the RE line was lower than that of the WT line. Transcriptome analysis showed that RE lines up-regulated genes enriched in cell wall organization or biogenesis pathway-related genes such as EXPA8, EXPA4, EXPA3, EXPA1, EXPB3, EXP10, PME53, PME34, PME36, XTH9, XTH6, XTH23, CESA1, CESA3, CES9; FLA11, FLA16 and FLA7 genes. These genes play an important role in NaHCO3 stress. Our study showed that the interference expression of the PsnWRKY70 gene can enhance the tolerance of NaHCO3 in poplar.

Exogenous Application of GABA Alleviates Alkali Damage in Alfalfa by Increasing the Activities of Antioxidant Enzymes

Alfalfa (Medicago sativa L.) is a widely grown and important forage crop. However, alkali stress is detrimental to alfalfa yield and nutritional quality. Gamma-aminobutyric acid (GABA) is a signaling molecule, it participates in and responds to metabolic regulation related to plant growth and development and stress. In this study, we clarify the effect of spraying alfalfa seedlings with GABA on the alkali tolerance of the seedlings. We determined that exogenous application of GABA at 75 mmol/L improved the resistance of alfalfa seedlings to alkali stress caused by exposure to 100 mmol/L NaHCO3, pH 8.5. Exogenous GABA significantly increased the chlorophyll content, the accumulation of soluble sugars in the plants, significantly decreased their relative electrical conductivity, malondialdehyde (MDA), superoxide anion (O2−) and hydrogen peroxide (H2O2) contents, and significantly increased the activities of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD). Exogenous GABA increased the activities of GAD and GABA-T, increased the content of glutamate and endogenous GABA, and regulated the expression of the genes MsGAD, MsGABA-T and MsGDH. In alfalfa plants that survived for a long time, compared to the control group, root length and fresh weight were significantly higher. Exogenous GABA had a positive effect on the resistance of alfalfa seedlings to alkali stress, and the effect was closely associated with GAD and GABA-T activity, glutamate content and the levels of endogenous GABA and antioxidants. This work provides a new method for the cultivation of early-stage alfalfa seedlings under low or moderate alkali stress conditions through the application of 75 mmol/L GABA.

Hydrochemistry characteristics of groundwater with the influence of spatial variability and water flow in Hetao Irrigation District, China.

Groundwater is an important resource of water in arid and semi-arid agricultural regions. Thus, identification of hydrogeochemical characters and the influence of geospatial variability and flow pooling are of significance on groundwater resources management and making irrigation decisions in salinized areas. The study specifically focused on the Hetao Irrigation District located in the semi-arid region of northern China. A total of 85 groundwater samples (42 from the upstream Shenwu Irrigation Area (SWIA), 43 from the downstream Wulate Irrigation Area (WLTIA)) were collected, and 15 water quality indexes were analyzed. Methods including mathematical statistics, Piper diagram, Gibbs model, forward succession model, and ionic rations were used to analyze the hydrochemical characteristics and evolution mechanisms, RSBC, PS, SAR, WQI were selected to evaluate water quality and irrigation suitability from the perspective of salt and alkali damage. Results showed that the groundwater of the study area is weakly alkaline, SWIA is mainly fresh water (47.62%), WLTIA is mainly brackish water (65.12%), and the hydrochemistry of the groundwater consists of Cl-Na type and Cl·SO-Ca·Mg. The solute content of downstream (WLTIA) is higher than that of upstream (SWIA), Na+ and Cl- have obvious advantages in WLTIA, and they are the main contribution indicators of groundwater TDS in the study area. The groundwater is subjected to the ongoing influence of rock weathering, ions exchange, and evaporate crystallization Na+ mainly originates from the dissolution of evaporate salt rock and silicate rock, and Ca2+ from the dissolution of gypsum and carbonate. The order of contribution of different rocks is evaporation rock > silicate rock > carbonate rock. Based on the classifications of sodium absorption ratio (SAR), residual sodium bicarbonate (RSBC), and potential salinity (PS), most of the groundwater samples are unsuitable for irrigating, and the groundwater quality of the SWIA is better than that of the WLTIA.

Endogenous bioactive gibberellin/abscisic acids and enzyme activity synergistically promote the phytoremediation of alkaline soil by broomcorn millet (Panicum miliaceum L.)

Broomcorn millet (Panicum miliaceum L.), an important food crop, grows in arid and semi-arid areas that face soil saline-alkalization. To date, no studies have investigated the mechanisms by which broomcorn millet seeds respond to and tolerate alkali stress. In this study, six broomcorn millet genotypes (B102, B220, B269, B279, B289, and B297) were selected to explore the physiological and molecular mechanisms of alkali stress at the germination stage. The results showed that alkali stress delayed the germination of broomcorn millet, and α-amylase activity was positively correlated with the germination rate. After alkali stress, the genotypes with lower alkali damage rates exhibited stronger antioxidant defenses. Real-time polymerase chain reaction analysis showed that alkali stress downregulated gibberellic acid (GA) synthesis genes but upregulated GA inactivation and abscisic acid (ABA) synthesis genes. Similarly, seeds displayed lower GA concentrations and higher ABA concentrations after alkali stress. Therefore, the ratios of various GAs/ABA decreased within the range of 35.77% to approximately 96.45%. Additionally, genotypes associated with lower alkali damage rates had higher GA/ABA ratios. These findings indicate that the alkali tolerance of broomcorn millet at the germination stage may be attributed to higher GA/ABA ratios, higher α-amylase activity, and stronger antioxidant defense, which synergistically resist alkali stress. This study will contribute to molecular breeding aiming to enhance alkali-tolerance and restoration of alkaline soils.

Study on hydrogeochemical connection and water quality assessment of subsidence lake and shallow groundwater in Luling coal-mining area of the Huaibei coalfield, Eastern China

Abstract The surface water from subsidence lakes and shallow groundwater plays an important role for agriculture, industry and local communities in coal mining areas. The connection between the two types of water and quality, however, remains unclear. In this study, 37 samples were collected from a subsidence lake and shallow groundwater around Luling coal mine. The hydrogeochemisty data and formation mechanisms were analyzed to reveal the connection proof. Compared with shallow groundwater, the surface water from the subsidence lake has a higher content of Na+ and HCO3−. For the two types of water samples, Na+ and Mg2+ are two most abundant cations, followed by Ca2+. The contents of anions followed the same order: HCO3− > SO42− > Cl−. The water samples were controlled by NaHCO3 (99.3%) type. The chemical composition of the two types of water were similar, which are all mainly influenced by silicate minerals weathering and ion-exchange interactions, among which ion-exchange interactions were more intense than in shallow groundwater. The recharging source of the two types of water mainly came from atmospheric precipitation. The two waters in the study area, in general, showed the risk of high salt and low-moderate alkali damage. The outcomes provide a better understanding of the subsidence lake and groundwater and it will help utilization of water resources.

The Alkali Tolerance of Broomcorn Millet (Panicum miliaceum L.) at the Germination and Seedling Stage: The Case of 296 Broomcorn Millet Genotypes.

Broomcorn millet (BM), one of the earliest domesticated cereal crops originating in northern China, can tolerate extreme conditions, such as drought and high temperatures, which are prevalent in saline-alkali, arid, and barren landscapes. However, its adaptive mechanism to alkali stress is yet to be comprehensively understood. In this study, 80 and 40 mM standard alkali stress concentrations were used to, respectively, evaluate the alkali tolerance at the germination and seedling stages of 296 BM genotypes. Principal component analysis (PCA), Pearson's correlation analysis, and F-value comprehensive analysis were performed on the germination parameters (germination potential, germination index, germination rate, vigor index, root length/weight, sprout length/weight, and alkali damage rate). Based on their respective F-values, the BM genotypes were divided into five categories ranging from highly alkali resistant to alkali sensitive. To study the response of seedlings to alkaline stress, we investigated the phenotypic parameters (plant height, green leaf area, biomass, and root structure) of 111 genotypes from the above five categories. Combining the parameters of alkali tolerance at the germination and seedling stages, these 111 genotypes were further subdivided into three groups with different alkali tolerances. Variations in physiological responses of the different alkali-tolerant genotypes were further investigated for antioxidant enzyme activity, soluble substances, malondialdehyde (MDA) content, electrolyte leakage rate, and leaf structure. Compared with alkali-sensitive genotypes, alkali-tolerant genotypes had high antioxidant enzyme activity and soluble osmolyte content, low MDA content and electrolyte leakage rate, and a more complete stomata structure. Taken together, this study provides a comprehensive and reliable method for evaluating alkali tolerance and will contribute to the improvement and restoration of saline-alkaline soils by BM.

Irrigation Suitability Assessment of Groundwater in an Open Mining Area in Grassland Area

In this paper, the investigation of groundwater in open-pit coal mine in grassland was carried out. The hydrochemical parameters of groundwater were detected. The chemical types of the groundwater were analyzed. The temporal variation characteristics of groundwater parameters were studied, and the suitability of the irrigation water quality was analyzed. The results showed that the main hydrochemical types of groundwater were SO4 2-•Cl--Na+•Mg2+ and SO4 2-•Cl--Na+•Mg2+(Ca2+). USSL analysis showed that most of the groundwater samples in the study area belonged to the type of high salinization and low alkali damage. Wilcox diagram analysis showed that most of the groundwater was in good and usable water quality area, and no groundwater sample was in unusable area. The results of single factor index SAR, %Na, RSC and PI analysis showed that most of groundwater was suitable for irrigation. Therefore, the groundwater in the study area was generally suitable for irrigation in pastoral areas. This study is of great significance to the rational development and utilization of groundwater resources.

Different tolerance mechanism to alkaline stresses between Populus bolleana and its desert relative Populus euphratica

Populus bolleana Lauche. (P. bolleana) and Populus euphratica Oliv. (P. euphratica) separately survive in mild and moderate alkaline soil conditions. The aim of this study was to explore the underlying mechanism for the different alkaline tolerance in the two poplar species. Young saplings of two poplar species were grown in moderate alkaline soil, and the young and old leaves of the two poplars were separately analyzed by ion concentration, allocation and distribution, transcript variation of different genes involved in ion transport and nitrogen assimilation, nitrogen metabolism, organic acid, leaf pigments, and redox responses. Excess Na+ under alkali stress was mainly allocated to old leaves in P. bolleana. However, excess Na+ was allocated to both young and old leaves in P. euphratica, and was balanced by enhanced levels of Mg2+, Ca2+, and SO42−, with no change in oxidative parameter. The reduction of nitrate nitrogen occurred under alkali stress in both species; P. euphratica acclimated to alkali stress by more flexible regulation of N metabolism and nitrate absorption than P. bolleana. Our results strongly indicated different alkali tolerance mechanisms in P. bolleana and P. euphratica. P. bolleana protects young tissues via profound accumulation of Na+ and confining damage effects into the old leaves under alkali stress, while P. euphratica can effectively compartmentalize excess Na+, keep its ion balance, and adjust nitrogen transport and metabolism in both young and old leaves to avoid alkali damage.

Efficacy and mechanism of rabbit corneal stromal cell-induced adipose-derived mesenchymal stem cell amnion transplantation for corneal alkali burn

Background Corneal chemical burn is one of blinding eye diseases.Previous therapies for corneal chemical burn is limited to certain extent.However, transplantation of adipose-derived mesenchymal stem cells (ADSCs) for corneal diseases is drawing more and more attention. Objective This study was to observe the effect of rabbit ADSCs transplantation for ocular alkali burns and explore its mechanism. Methods Rabbit corneal stromal cells (CSCs) were isolated and cultured by suspended matrix method, and rabbit ADSCs were obtained and digested from inguinal fat tissue with enzyme digestion method (0.25% trypsin) and identified by flow cytometry.CSCs cocultured with ADSCs, and CSCs-induced ADSCs were identified by double-label of with immunofluorescence and reverse transcription PCR (RT-PCR). Then induced or uninduced ADSCs were inoculated on amniotic membrane to prepared ADSCs-amnion patch.Corneal alkali burn models were established in the right eyes of 60 New Zealand rabbits by placing a filter paper with 1% NaOH solution at the central cornea for 50 seconds.The models were randomized into the induced ADSCs+ amnion implanted group, the uninduced ADSCs+ amnion implanting group, amnion implanted group and model group.Corneal opacification and neovascular area were examined and corneal inflammation was graded by slit lamp microscope 1 week, 2 weeks and 1 month after surgery.The contents of CD45, interferon-γ (IFN-γ) and interleukin-10 (IL-10) in corneal homogenate as well as vascular endothelial growth factor (VEGF) in aqueous humor were detected by ELISA assay.The use and care of experiment animals followed the Statement of ARVO. Results ADSCs showed the positive responses for CD105, CD29, CD44 with the positive rate 90.23%, 88.56% and 98.88%, respectively.CSCs was positively reactive for vimentin.The double-label staining was positive after coculture of CSCs with ADSCs.Hematoxylin-eosin stain exhibited that ADSCs grew well on the amnion.Corneal porcelain opacity and a lot of new blood vessels were seen in the model group, and corneal was clear in the induced ADSCs+ amnion implanted group 1 month after surgery.The inflammatory scores were 1.65±0.18, 2.05±0.17, 2.68±0.25, 2.90±0.18, and the areas of neovasculization were (10.59±1.78), (22.58±1.63), (37.98±1.90), (45.37±1.65)mm2 respectively in the induced ADSCs+ amnion implanted group, uninduced ADSCs+ amnion implanted group, amnion implanted group and the model group.The inflammatory scores of 1 week, 2 weeks, 1 month after operation among the four groups had statistically significant differences（F=280.826, 330.172, 465.707, all at P=0.000), and the areas of neovasculization of 1 week, 2 weeks, 1 month after operation among the four groups had statistically significant differences（F=60.020, 670.811, 1 510.231, all at P=0.000), the inflammatory scores in the induced ADSCs+ amnion implanted group were remarkably lower than those of the other groups, the areas of neovasculization in the induced ADSCs+ amnion inplanted group were smaller than those of the other groups (all at P<0.01). In 1 month after surgery, the contents of CD45, IL-10, IFN-γ in cornea and VEGF in aqueous humor were statistically different among the groups（F=916.545, 1 739.358, 462.134, 129.126, all at P=0.000). Compared with the uninduced ADSCs+ amnion implanted group, amnion implanted group and the model group, CD45 and IFN-γ contents were declined, and IL-10 content was elavated in the induced ADSCs+ amnion implanted group (all at P<0.01). In addition, VEGF contents in aqueous humor were significantly lower than those in the other groups (all at P<0.01). Conclusions Rabbit CSCs-induced ADSCs amnion patch transplantation is effective for the reconstruction of ocular surface after alkali damage probably by differentiation of ADSCs into epithelial-like cell after CSCs induced.Moreover, amnion can alleviate immuno-inflammatory response and suppress neovascularization. Key words: Adipose-derived mesenchymal stem cells; Transplantation; Amniotic membrane; Alkali burn, ocular; Differentiation; Corneal stromal cells

Redox proteomic evaluation of bleaching and alkali damage in human hair

Protein modification and damage in human hair, resulting from environmental, cosmetic and grooming stresses, create changes to visual and tactile characteristics and correlates with consumer perception of quality. This study outlines molecular-level evaluation of modification resulting from peroxide (bleaching) and alkaline straightening (relaxing) treatments. Redox proteomic profiling of virgin, bleached and relaxed hair tresses was performed, with comprehensive qualitative characterization of modification and semi-quantitative evaluation of damage through adaptation of a new damage scoring system. Modifications were mapped to specific locations in the hair proteome and a range of potential damage marker peptides identified. Virgin hair contained a baseline level of modification, consistent with environmental oxidative insult during hair growth. Hydrogen peroxide bleaching resulted in significantly increased levels of oxidative damage observable at the molecular level. This treatment also resulted in enhanced levels of dehydroalanine and dehydration products; modifications typically associated with alkali or thermal treatment and not previously been reported as a product of hair bleaching. Relaxation treatment with sodium hydroxide increased the formation of dehydroalanine and dehydration products and moderately enhanced the levels of oxidation. Cysteine was the predominant modification site for both bleaching and alkali damage. This study validates the utility and power of redox proteomic-based approaches to characterizing hair modification. This offers potential application to a wide range of damage types, as well as evaluation of new damage mitigation and repair technologies.

Mapping of QTLs Underlying Tolerance to Alkali at Germination and Early Seedling Stages in Rice

A double haploid (DH) population including 120 lines derived from a cross between indica rice (Oryza sativa L.) TN1 and japonica rice CJ06 was used to detect quantitative trait loci (QTLs) for 10-trait relative values of alkali damage at germination period and early seedling stage under 0.15% Na2CO3 stress. Correlation analyses showed that alkali damage rate in germination period (ADG) had significant positive correlation with relative germination energy (RGE), relative germination rate (RGR) and relative germination index (RGI), and alkali damage rate at early seedling stage (ADS) had significantly correlation with relative seedling height (RSH), relative root length (RRL), relative root number (RRN) and relative seedling dry weight (RDW). ADG and ADS can be used as evaluation indexes of alkaline tolerance in rice. By using QTLNetwork 2.0 software, 14 additive QTLs and 13 epistatic QTLs controlling the tolerance to alkali were mapped. Two main effect QTLs were detected in same region, RM251–RM3280, on chromosome 3, and three main effect QTLs were mapped between RM3286 and RM1279 on chromosome 7. Epistasis analysis showed that some epistatic loci, like RM1–RM1195, RM1358–RM290, RM1279–RM505, and RM1246–RM519 on chromosome 1, 2, 7, and 12 respectively were important under alkali stress, included two or more epistatic QTLs, indicating that the QTLs displayed their effects through different ways of interaction. Among the key loci under alkali stress one may be pleiotropic or some closely linked each other. Comparing QTLs with those found in other researches, some alkali resistance QTLs were likely to be in the same region with some salt resistance QTLs. A presume was made that QTLs in this articlemight include two types, one for resistance to ions (K+ or Na+) stress and other for resisttance to high pH stress, the latter may play an important role for tolerance to alkali. Many rice varieties have different resistance QTLs for alkali stress; we can pyramid them through marker-assistant selection to breed varieties suitable to growth in saline-alkalized land.

Mapping of QTL Underlying Tolerance to Alkali at Germination and Early Seedling Stages in Rice

To detect quantitative trait loci (QTLs) associated with tolerance to alkali damage, 120 double haploid (DH) lines derived from the cross between TN1 ( Oryza sativa L. subsp. indica) and Chunjiang 06 ( O. sativa L. subsp. japonica) were used as mapping population. The seeds were treated with 0.15% Na 2CO 3 (alkali stress) and distilled water (control) and 10 traits were determined as indicators for alkali damage at germination and early seedling stages. The alkali damage rate in germination stage (ADG) positively correlated ( P < 0.05) with the relative germination energy (RGE), relative germination rate (RGR), and relative germination index (RGI); and the alkali damage rate at early seedling stage (ADS) had significantly correlation with relative seedling height (RSH), relative root length (RRL), relative root number (RRN), and relative seedling dry weight (RDW). ADG and ADS could be used as indicators for alkaline tolerance in rice. Using QTLNetwork2.0 software, 14 additive QTLs and 13 pairs of epistatic QTLs controlling the tolerance to alkali were mapped. Two main-effect QTLs were detected in the region of RM251– RM3280 on chromosome 3, and 3 main-effect QTLs were mapped between RM3286 and RM1279 on chromosome 7. Epistatic loci, such as RM1– RM1195, RM1358– RM290, RM1279– RM505, and RM1246– RM519 on chromosomes 1, 2, 7, and 12, respectively, were important under alkali stress. The key loci under alkali stress may be pleiotropic or closely linked to each other. Some alkali resistance QTLs were likely to be in the same regions with salt resistance QTLs reported earlier. The QTLs detected in this study might be 2 types corresponding to resistances to ions (K + or Na +) stress and high pH stress, respectively, and the latter probably plays an important role in the tolerance to alkali in rice.

Radiological spectrum of late sequelae of corrosive injury to upper gastrointestinal tract. A pictorial review.

To evaluate the radiological spectrum of sequelae of corrosive acid and alkali injury to the upper gastrointestinal (GI) tract using barium contrast examination. Barium contrast radiographic films of 155 patients with a history of corrosive ingestion, acid in 120 and alkali in 35 patients with grade 2b and 3 injury on initial endoscopy, were retrospectively evaluated. Barium contrast examination of the upper GI tract was performed in the course of follow-up, beyond 3 weeks of corrosive ingestion. The esophagus was involved in 131 patients and the stomach in 74. Fifty patients had simultaneous involvement of esophagus and stomach. Radiological findings in the esophagus were solitary or multiple strictures of varying length, intramural pseudodiverticula, and carcinoma in long-standing corrosive injury. The stomach showed cicatrization, predominantly involving the antrum, linitis plastica type deformity with multiple pseudodiverticula. There was no difference in the radiological findings as to the type of corrosive ingested. Barium examination of the upper GI tract is useful in the evaluation of late sequelae of corrosive injury (acid/alkali). There was no difference in the radiological findings as to the type of corrosive ingested. Thus, contrary to general belief, we found that acid and alkali damage both the esophagus and the stomach with equal degree of severity.

Regulatory aspects of alkali tolerance induction in Escherichia coli.

Escherichia coli shifted from external pH (pH(O)) 7.0 to pH(O) 8.5-9.5 rapidly becomes tolerant to pH(O) 10.0-11.5, induction of tolerance (alkali habituation) being dependent on periplasmic or external alkalinization with either NaOH or KOH. Induction needs protein synthesis and makes organisms resistant to DNA damage by alkali and better able to repair any damage that occurs. Induction of tolerance was reduced by glucose (not reversed by cAMP) and by amiloride, was dependent on DNA gyrase and was abolished by fur and himA lesions (the latter suggests IHF involvement). Tolerance induction was not prevented by L-leucine, FeCl3 or FeSO4 nor by hns or relA mutations. Habituation probably involves attachment of IHF upstream of the promoter leading to DNA bending which switches on transcription. Habituation is aberrant in nhaA mutants, so ability to resist alkali damage may only arise if NhaA is induced, with extrusion of Na+ by this antiporter during alkali challenge. In accord with one tolerance component involving NhaA induction, beta-galactosidase formation from nhaA-lacZ fusions at pH(O) 9.0 was inhibited by glucose and amiloride.

The histochemical pattern of mechanically or chemically injured rabbit cornea after aprotinin treatment: relationships with the plasmin concentration of the tear fluid.

Plasmin, a serine protease, was recently found to be involved in corneal ulcerative processes in humans and rabbits. In our experiments, plasmin activity was found in the tear fluid after mechanical and chemical damage of the rabbit cornea, such as de-epithelization and burning with alkali. The plasmin concentrations in the tear fluid were dependent on the severity of injury. The highest plasmin activity (2.0-3.0 micrograms ml-1) occurred after severe alkali damage to large areas of the cornea, and the lowest activity (0.4-1.0 micrograms ml-1) after mechanical injury (de-epithelization). Plasmin concentrations up to 1.0 micrograms ml-1 were associated with increased activities of lysosomal hydrolases in epithelial cells and keratocytes beneath the epithelium. Plasmin activities increased as the inflammatory reaction developed. When plasmin activity in the tear fluid was higher than 1.0 micrograms ml-1, inflammatory cells were found in the corneal stroma. Levels of 1.5-2.0 micrograms ml-1 were connected with higher numbers of inflammatory cells (particularly polymorphonuclear leukocytes) with increased activities of lysosomal hydrolases. Very high plasmin activities (2.5-3.0 micrograms ml-1) accompanied corneal ulcerative processes. The local application of aprotinin (Trasylol, Bayer), an inhibitor of plasmin, and also of some other proteases, was found to be necessary for the healing of severe corneal injuries in which highly elevated plasmin activity in the tear fluid and inflammatory cellulization of the cornea occurred (severe damage).(ABSTRACT TRUNCATED AT 250 WORDS)

The Effect of Solvent Extraction on the Hydrothermal and Alkaline Stability of Wool

It is shown that the decrease in tearing strength of wool fabrics due to treatment with boiling water or buffer solutions (pH 2–10) was enhanced if the fabric had been previously extracted with chloroform/methanol. The increased susceptibility of the wool to high-temperature or alkali damage may have been due to the extraction of components from the cell-membrane complex as is known to occur during chloroform/methanol treatments. Extraction of wool fabric with other solvents also caused decreases in tearing strength when the wool was subsequently treated with boiling aqueous solutions. These observations may have important implications for the study of wool damage during dyeing. The breaking load of fabrics boiled in buffer of pH 7 was not decreased by prior extraction of the samples with any of the solvent systems studied. Yellowing of the wool fabric owing to boiling in aqueous solutions was unaffected by the solvent pretreatments.

Ion bombardment of alkali halides, I. Range and damage profiles of protons in KCl

Abstract The depth of the layer of F-centers created by protons in the : nergy intervals 0.5 to 2.3 MeV and 4 to 15 MeV was measured in single crystal KG. Photomicrographs were taken of irradiated crystals using F-band light. The optical density of the negatives was measured and calibrated to give a graph of optical density versus distance into the crystal. Using the stopping power of pro to ns in argon, a “theoretical” range-energy curve was calculated. Experimental results correspond to this curve within experimental error. The damage profiles produced by protons in the high energy interval showed Bragg peaks, consistent with the rise in energy-loss-rates of slowing protons. The damage profiles produced by protons in the low energy interval did not exhibit Bragg peaks, a feature attributed to the combined effect of reduced F-center production efficiency of low energy protons and saturation in the F-center concentration.

Effects of Severe Alkali Treatment of Proteins on Amino Acid Composition and Nutritive Value

Amino acid analyses, protein quality assays, in vitro digestion and absorption tests and feeding studies with rats were conducted to study the effects of alkali treatment on food proteins under varying conditions of pH, temperature and time. Exposure of several high protein products to aqueous alkali at pH 12.2 resulted in the formation of the amino acid derivative lysinoalanine (LAL) which is poorly absorbed. The amount of LAL formed in isolated soy protein (ISP) upon exposure at pH 12.2 increased with rising temperature and a longer exposure period. The presence of LAL in proteins was attended with decreased contents of cystine and lysine, and decreased net protein utilization (NPU) values. More severe treatment of ISP with alkali of pH 12.2 at 60 or 80° also caused a decrease in serine content and in digestibility of the protein. The LAL content of ISP treated under various conditions showed a highly significant negative correlation with NPU values (r = - 0.96). The presence of LAL in proteins was a sensitive criterion of alkali damage. The NPU assays of ISP supplemented with amino acids showed methionine to be the first limiting amino acid and threonine the second. The decreased NPU of alkali-treated ISP could not be completely alleviated by amino acid supplementation, probably as a result of decreased utilization of threonine. Most of the essential amino acids from alkali-treated ISP were released at a relatively slow rate by pepsin-pancreatin digestion. Threonine and methionine were the only essential amino acids in an enzymatic digest of ISP which showed decreased absorption by everted intestinal sacs. Upon feeding rats diets with relatively high levels of proteins treated at pH 12.2 and 40° for 4 hours no clinical or histological abnormalities were observed other than an increased degree of nephrocalcinosis in females which could be prevented by additional dietary calcium.

49—SOME OBSERVATIONS ON CANARY COLORATION IN INDIAN RAW WOOLS

It is shown that pigments present in the suint are responsible for canary coloration in Indian raw wools. These pigments enter the fibre when the grease content is low. The grease content of the fibre and the pigment content of the suint undergo a periodic change, and hence the canary coloration recurs periodically in certain breeds of sheep. Although alkali damage has been observed in the canary-coloured fleeces no correlation was found between the intensity of the canary stain and the alkalinity of the suint.