Long-Term Effects of Methylmercuric Chloride on Three Generations of Brook Trout (Salvelinus fontinalis): Toxicity, Accumulation, Distribution, and Elimination

1976 ◽  
Vol 33 (12) ◽  
pp. 2726-2739 ◽  
Author(s):  
J. M. McKim ◽  
G. F. Olson ◽  
G. W. Holcombe ◽  
E. P. Hunt
Keyword(s):  
Brook Trout ◽  
First Generation ◽  
Second Generation ◽  
Salvelinus Fontinalis ◽  
Accumulation Rate ◽  
Three Generations ◽  
Methylmercuric Chloride ◽  
Toxicant Concentration ◽  
Concentration Factors ◽  
First And Second Generation

During a 144-wk period three generations of brook trout (Salvelinus fontinalis) were continuously exposed to mean water concentrations of methylmercuric chloride (MMC) of 2.93, 0.93, 0.29, 0.09, 0.03, and <0.010 (control) μg Hg/liter. During the first 39 wk the highest concentration (2.93 μg Hg/liter) produced deformities and 88% mortality of first-generation adults. At an MMC concentration of 0.93 μg Hg/liter, second-generation trout developed deformities and all but one female died during the 108-wk exposure. No significant effects on survival, growth, or reproduction of second-generation trout were noted at any of the lower MMC concentrations. No toxic symptoms were observed in the third generation at the three lowest MMC concentrations. The maximum acceptable toxicant concentration (MATC) for brook trout exposed to MMC in this water with a hardness of 45 mg/liter (as CaCO3) and a pH of 7.5 fell between 0.93 and 0.29 μg Hg/liter. The mean 96-h LC50 for yearling (200 g) and 20-wk-old (12 g) juvenile brook trout exposed to MMC was 75.0 μg Hg/liter, and the application factor (MATC/96-h LC50) lies between 0.004 and 0.013. The accumulation rate of mercury by eight selected tissues of first-generation trout exposed to MMC was relatively rapid at all MMC concentrations tested. The 2-wk tissue Hg: water Hg concentration factors ranged from 1 × 103 to 12 × 103, depending on the tissue, whereas after 28–38 wk of exposure the maximum tissue Hg: water Hg concentration factors for both first- and second-generation trout ranged from 6.9 × 103 to 6.3 × 104. The blood, spleen, and kidney accumulated mercury most rapidly and contained the highest residues in both first- and second-generation trout followed by liver, gill, brain, gonad, and muscle in order of decreasing mercury residues. There was no significant elimination of mercury from the tissue of first- or second-generation fish, yet a "steady state" (micrograms mercury per gram = constant) was reached in all tissues after 20–28 wk of continuous water exposure. Monomethylmercury made up 90–95% of the total mercury present in muscle, the only tissue analyzed for this compound. Mean muscle residues in first-generation trout, dying after 16–28 wk of exposure to 2.93 μg Hg/liter and in second-generation trout, dying after 64–100 wk of exposure to 0.93 μg Hg/liter, were 23.5 and 9.5 μg Hg/g, respectively.

Long-Term Effects of Lead Exposure on Three Generations of Brook Trout (Salvelinus fontinalis)

1976 ◽  
Vol 33 (8) ◽  
pp. 1731-1741 ◽  
Author(s):  
G. W. Holcombe ◽  
D. A. Benoit ◽  
E. N. Leonard ◽  
J. M. McKim
Keyword(s):  
Brook Trout ◽  
Second Generation ◽  
Salvelinus Fontinalis ◽  
Residue Analysis ◽  
Kidney Tissue ◽  
Third Generation ◽  
Long Term Effects ◽  
Three Generations ◽  
Toxicant Concentration ◽  
Liver And Kidney

Exposure of three generations of brook trout (Salvelinus fontinalis) to mean total lead concentrations (0.9–474 μg/liter) showed that all second-generation trout exposed to 235 and 474 μg Pb/liter and 34% of those exposed to 119 μg Pb/liter developed severe spinal deformities (scoliosis). Scoliosis also appeared in 21% of the newly hatched third-generation alevins exposed to 119 μg Pb/liter, and weights of these fish 12 wk after hatch were significantly reduced. Gill, liver, and kidney tissues of first- and second-generation brook trout accumulated the greatest amount of lead. Only small amounts accumulated in the edible muscle. An equilibrium of lead residues was reached in liver and kidney tissue from second-generation fish after 70 wk of exposure, but not in gill tissue. Fish exposed to 119 μg Pb/liter and then placed in uncontaminated control water for 12 wk showed a 70, 78, and 74% loss in micrograms Pb per gram for gill, liver, and kidney tissue, respectively, and a 39, 56, and 35% loss, respectively, in the total micrograms of Pb in the whole tissue. Residue analysis of eggs, alevins, and juveniles showed that lead was accumulated during these life stages. The maximum acceptable toxicant concentration (MATC) for brook trout in water with a hardness of 44 mg/liter (as CaCO3) and a pH of 6.8–7.6 lies between 58 and 119 μg/liter for total lead and between 39 and 84 μg/liter for dissolved lead. The MATC was based on the development of scoliosis in second- and third-generation fish and the reduced growth of 12-wk-old third-generation trout. The 96-h LC50 for brook trout was 4100 μg/liter based on total lead and 3362 μg/liter based on dissolved lead; therefore, the application factor (MATC/96-h LC50) lies between 0.012 and 0.029 for both total and dissolved lead.

Assimilation of the Puerto Ricans on the Mainland

1968 ◽  
Vol 2 (2) ◽  
pp. 21-39
Author(s):  
John J. Macisco
Keyword(s):  
United States ◽  
First Generation ◽  
Second Generation ◽  
Puerto Ricans ◽  
The United States ◽  
Social Scientists ◽  
First Marriage ◽  
Labor Force Status ◽  
Age At First Marriage ◽  
First And Second Generation

Social scientists have repeatedly tried to specify the process whereby assimilation takes place. This article points out the value of socio-demographic analysis in the study of assimilation, by describing the characteristics of Puerto Ricans on the United States mainland. In order to assess the direction of change between the first and second generation Puerto Ricans, data for the total United States population are also presented. Most of the data are drawn from the 1960 Census. First generation Puerto Ricans are compared with the second generation along the following dimensions: age, education, labor force status, income, occupation, age at first marriage, percent outgroup marriage and fertility. The Author concludes that second generation Puerto Ricans are moving in the direction of total United States averages.

scholarly journals Why do first and second-generation young migrants volunteer? The Migrant Volunteerism Motivation Model (MVMM)

2019 ◽  
Vol 7 (2) ◽  
pp. 1089-1107 ◽  
Author(s):  
Sara Alfieri ◽  
Daniela Marzana ◽  
Sara Martinez Damia
Keyword(s):  
Transition To Adulthood ◽  
Process Model ◽  
First Generation ◽  
Second Generation ◽  
Maintenance Phase ◽  
Structured Interviews ◽  
Sub Saharan ◽  
Italian Context ◽  
First And Second Generation ◽  
Motivation Model

The following study aims at inquiring into the motivations behind young migrants’ volunteerism in civic organizations in Italy, namely in starting and maintaining their engagement (preliminary vs. maintenance phase). The term “young migrants” refers to first and second generation of migrants who deal with two challenges: the transition to adulthood and the acquisition of a cultural identity. We conducted semi-structured interviews with 37 Sub-Saharan young migrants living in Italy (18-32 years old), 19 of first generation (1G) and 18 of second generation (2G). The Omoto and Snyder’s Volunteer Process Model (VPM, 1995) was used as an underpinning theoretical framework and a guide for the interpretations of the results. The findings indicate that a) motivations included in the VPM are also found for young migrants, b) some of these motivations take particular meaning for young migrants, c) some motivations are not included in the VPM and are specific of this sample. We named these last motivations: social norms, advocacy and ethno-cultural. In addition, some considerations may be advanced regarding the generation and the phase of motivation: 1G migrants are particularly moved by the importance of integration in the Italian context and by the promotion of their ethnic group while 2G migrants reported mostly the desire to understand their roots. The values, the concern for the community and the longing to develop relationships are the motivations for which all young migrants continue to volunteer; however, 1G migrants are also sustained by advocacy and ethno-cultural motivations. Implications and future directions are discussed.

scholarly journals The performance and genetic variation of first and second generation tropical alfalfa (Medicago sativa)

2021 ◽  
Vol 22 (6) ◽  
Author(s):  
Bambang Suwignyo ◽  
LUKMANA ARIFIN ◽  
NAFIATUL UMAMI ◽  
MUHLISIN MUHLISIN ◽  
BAMBANG SUHARTANTO
Keyword(s):  
Organic Matter ◽  
Genetic Variation ◽  
Medicago Sativa ◽  
Crude Protein ◽  
Dry Matter ◽  
First Generation ◽  
Second Generation ◽  
Seed Viability ◽  
Nutrient Content ◽  
First And Second Generation

Abstract. Suwignyo B, Arifin L, Umami N, Muhlisin, Suhartanto B. 2021. The performance and genetic variation of first and second generation tropical alfalfa (Medicago sativa). Biodiversitas 22: 3265-3270. This study aimed to compare the growth performance, nutrient content, seed viability, and genetic variation of first- and second-generation alfalfa (Medicago sativa L.). First and second-generation alfalfa seeds were obtained from the Forage and Pasture Science Laboratory, Department of Animal Nutrition and Feed Science, Faculty of Animal Science, Universitas Gadjah Mada (UGM), Yogyakarta, Indonesia. First generation alfalfa (F1) seeds were obtained from cross breeding of two different parental alfalfa varieties, namely, Canadian and local. The second-generation (F2) seeds were obtained from plants of the first-generation alfalfa (F1). A randomized design experiment was conducted using the two types of alfalfa (first- and second generation). Alfalfa from Canada as female parent was used as the baseline in the genetic masker test. Seeds were planted in a polybag, watered twice a day, and received 12 hours of daylight and 4 hours of artificial light. Plants were then harvested 8 weeks after planting by cutting the plant canopy. Genetic variation was examined using the Inter Simple Sequence Repeat (ISSR) method followed by descriptive analysis. Germination, plant height, dry matter content, organic matter, and crude protein were assessed as variables using a Student’s T-test. Our results showed that germination, plant height, leaf color, and nutrient content (dry matter, organic matter, and crude protein) of the first- and second-generation alfalfa plants were not significantly different. However, the second-generation alfalfa demonstrated better seed viability than the first generation plants, then it can be categorized as a new genotype (tropical alfalfa) based on genetic variation analysis.

Differential Impairments in Incentive Learning Caused by First‐ and Second‐ Generation Antipsychotic Drugs

2016 ◽  
Author(s):  
Matthew Florczynski
Keyword(s):  
Neural Control ◽  
First Generation ◽  
Antipsychotic Drugs ◽  
Second Generation ◽  
Operant Chamber ◽  
Incentive Learning ◽  
Dopamine Receptor Antagonists ◽  
Natural Response ◽  
Second Generation Antipsychotic ◽  
First And Second Generation

Schizophrenia is a neuropsychiatric disorder characterized by increased function of dopamine in the brain.  Dopamine release is a natural response to reward.  It promotes incentive learning (IL), a process by which neutral stimuli acquire the ability to elicit approach and other responses.  A recent model characterizes dopamine‐mediated IL as a progressive process with early and late stages accompanied by a shift in neural control from the nucleus accumbens (NAc) to the dorsolateral striatum (DLS).  A parallel can be drawn to differences in regionally specific neural responses generated by first‐ and second‐generation antipsychotic drugs (APDs) used to treat schizophrenia.  APDs are dopamine receptor antagonists, but first‐generation APDs affect the NAc and DLS while second‐generation APDs affect primarily the NAc.  We compared the effects of APDs on IL. Rats (N = 48) were trained to press a lever forfood pellets in an operant chamber.  Intraperitoneal injections (1 hr before testing) of the first‐generation APD haloperidol (0,0.05,0.10,0.20 mg/kg) or of the second‐generation APD risperidone (0,0.20,0.40,0.80 mg/kg) induced dose‐dependent suppression of lever pressing on days 1‐4, with the highest dose groups failing to demonstrate any evidence of previous learning on day 5 when tested drug‐free.  On days 16‐20 haloperidol induced a day‐to‐day suppression not seen with risperidone.  The results suggest that the effects of first‐ and second‐generation APDs on learning processes putatively mediated by the NAc and DLS can be differentiated experimentally.  The findings imply that APDs may differentially affect IL inpatients with schizophrenia.  

4.  Differential Impairments in Incentive Learning Caused by First‐ and Second‐ Generation Antipsychotic Drugs

2016 ◽  
Author(s):  
Matthew Florczynski
Keyword(s):  
Neural Control ◽  
First Generation ◽  
Antipsychotic Drugs ◽  
Second Generation ◽  
Operant Chamber ◽  
Incentive Learning ◽  
Dopamine Receptor Antagonists ◽  
Natural Response ◽  
Second Generation Antipsychotic ◽  
First And Second Generation

Schizophrenia is a neuropsychiatric disorder characterized by increased function of dopamine in the brain.  Dopamine release is a natural response to reward.  It promotes incentive learning (IL), a process by which neutral stimuli acquire the ability to elicit approach and other responses.  A recent model characterizes dopamine‐mediated IL as a progressive process with early and late stages accompanied by a shift in neural control from the nucleus accumbens (NAc) to the dorsolateral striatum (DLS).  A parallel can be drawn to differences in regionally specific neural responses generated by first‐ and second‐generation antipsychotic drugs (APDs) used to treat schizophrenia.  APDs are dopamine receptor antagonists, but first‐generation APDs affect the NAc and DLS while second‐generation APDs affect primarily the NAc.  We compared the effects of APDs on IL. Rats (N = 48) were trained to press a lever for food pellets in an operant chamber.  Intraperitoneal injections (1 hr before testing) of the first‐generation APD haloperidol (0,0.05,0.10,0.20 mg/kg) or of the second‐generation APD risperidone (0,0.20,0.40,0.80 mg/kg) induced dose‐dependent suppression of lever pressing on days 1‐4, with the highest dose groups failing to demonstrate any evidence of previous learning on day 5 when tested drug‐free.  On days 16‐20, haloperidol induced a day‐to‐day suppression not seen with risperidone.  The results suggest that the effects of first‐ and second‐generation APDs on learning processes putatively mediated by the NAc and DLS can be differentiated experimentally.  The findings imply that APDs may differentially affect IL inpatients with schizophrenia.

One person, three identities? Examining re-politicization of ethnic, national, and Australian identities among 1.5-generation Taiwanese immigrants in Australia

2020 ◽  
pp. 144078332093415
Author(s):  
Yao-Tai Li
Keyword(s):  
First Generation ◽  
Second Generation ◽  
Identity Negotiation ◽  
Generation 1.5 ◽  
The Political ◽  
Host Society ◽  
1.5 Generation ◽  
Ethnic Chinese ◽  
Second Generation Immigrants ◽  
First And Second Generation

Immigrants of the 1.5-generation (1.5-ers) differ from first- and second-generation immigrants because they are generally better immersed in the culture of the host society than the first generation; yet, compared to the second generation, they often have to renegotiate their identities in relation to parents, colleagues at work, and people in the host society during the processes of migration. Drawing on interview data from Taiwanese 1.5-ers in Australia, this article takes a further step and points out that in addition to the identity struggle between home and host country, Taiwanese 1.5-ers also identify as ethnic Chinese (Huaren) and constantly negotiate between these three identities (Huaren, Taiwanese, and Australian). This article argues that identity negotiation and hybridization is in nature a re-politicization process in which respondents are fully aware of the political meanings and power disparities of each identity. It is also a process whereby Taiwanese 1.5-ers mobilize, downplay, and hybridize specific identities based on time and context.

The role of style in the ethnolect: Style-shifting in the use of ethnolectal features in first- and second-generation speakers

2020 ◽  
Vol 24 (4) ◽  
pp. 861-880 ◽  
Author(s):  
Ksenia Gnevsheva
Keyword(s):  
Design Methodology ◽  
First Generation ◽  
Second Generation ◽  
The Other ◽  
Research Questions ◽  
Similarities And Differences ◽  
Style Shifting ◽  
Australian English ◽  
First And Second Generation

Aims and Objectives/Purpose/Research Questions: The paper aimed to investigate style-shifting in the use of ethnolectal features in first- and second- generation bilingual migrants. Design/Methodology/Approach: Three groups of speakers (first- and second-generation Russian–English bilinguals as well as monolingual Anglo Australians) were audio-recorded in three different styles (conversation, interview, and reading). Data and Analysis: Their production of the goose and trap vowels across the styles was analyzed quantitatively. Findings/Conclusions: Overall differences were found between the groups such that first- and second-generation speakers produced more Russian-like vowels compared to the monolinguals; with the biggest differences between the first-generation speakers and the other two groups. In terms of style-shifting, no significant differences were found in the monolingual speakers, and both first- and second-generation speakers were found to produce most Australian English-like vowels in the conversation style. At the same time, certain differences between the two bilingual groups surfaced, such as no significant differences in the first-generation speakers’ production of the goose vowel and in the vowels’ linguistic conditioning. Originality: Previous studies have compared ethnolects in the first- and second-generations of migrants and mainstream varieties in order to theorize ethnolect formation. Several studies have also investigated intraspeaker style-shifting between more ‘mainstream’ and more ‘ethnic’ in ethnolect speakers, but such style-shifting is rarely compared across generations. Significance/Implications: The similarities and differences between the two bilingual groups suggest that ethnolectal features may be originally derived from the community language but may be reallocated to other sociolinguistic meanings in the second generation.

Immigrant and second-generation Turkish entrepreneurs in Melbourne Australia

2015 ◽  
Vol 21 (2) ◽  
pp. 154-174 ◽  
Author(s):  
Yasemin Soydas ◽  
Torgeir Aleti
Keyword(s):  
First Generation ◽  
Second Generation ◽  
Government Support ◽  
Entrepreneurial Activity ◽  
Content Type ◽  
Positive Effects ◽  
Immigrant Entrepreneurs ◽  
Generation Immigrant ◽  
Business Establishment ◽  
First And Second Generation

Purpose – The purpose of this paper is to examine the key differences between first- and second-generation immigrant entrepreneurs in their path to entrepreneurship. The aim of the study is to better understand entrepreneurial motivations amongst immigrants by comparing first- and second-generation entrepreneurs in their motivation for business entry, reliance on co-ethnic market, use of social and financial capital, business planning and marketing practices. Design/methodology/approach – Using an interpretivist approach and a qualitative design, this study comprises 20 in-depth interviews with first- and second-generation Turkish entrepreneurs (TEs) in Melbourne, Australia. Turks in Australia were chosen because of their high level of entrepreneurial activity. In order to uncover deep-seeded motivations, participants were interviewed in a face-to-face format guided by a semi-structured interview guide. Findings – The second-generation TEs were distinctively different from their first-generation counterparts in motivation for business entry, business establishment and use of ethnicity. The analysis shows that although the generations differ in their approach to business establishment, they both appear to be drawn to entrepreneurship based on “pull factors”. This is in contrast with previous literature suggesting that first-generation immigrant entrepreneurs were motivated by “push factors”. Originality/value – This paper suggests that both first- and second-generation immigrant entrepreneurs are “pulled” into entrepreneurship voluntarily. While the first-generation entrepreneurs seem to be motivated/pulled by financial reasons, the second generation are motivated by opportunity recognition, status and ambition. Nevertheless, a lack of trust in government support agency is found within both generations. Thus, outreach activities towards entrepreneurial immigrant communities may have positive effects for the economy as well as in the integration of ethnic enclaves.

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