Germ line mosaicism

Mosaicism in germ cells has been recognized, over the past few years, as an important and relatively frequent mechanism at the origin of genetic disorders. There are two possibilities for the existence of such a mosaicism: one is that the mutation occurs in a germ cell that continues to divide. The other possibility is that the mutation occurs very early in a somatic cell before the separation to germinal cells and is therefore present both in somatic and germinal cells. Depending on various factors, such as the gene involved and/or the degree of mosaicism, the carrier of a somatic and germline mosaicism may be asymptomatic or may present with various symptoms of the disease. There are still relatively few reports in the literature in which the origin of germ-line mosaicism has been analyzed; nevertheless, they allow for a better insight into the mechanisms involved. In some diseases, such as osteogenesis imperfecta, new mutations are often present as asymptomatic somatic and germline mosaicism in one of the parents of the propositus. In other disorders, such as neurofibromatosis, somatic mosaicism is very rare in the parents of the propositus, perhaps since such mosaicism causes clinical symptoms. These differences are particularly important for genetic counseling in order to evaluate the risk for another affected child after the birth of the propositus. Received: 15 September 1997 / Accepted: 12 January 1998     

Cell line provenance

Cultured cell lines have become an extremely valuable resource, both in academic research and in industrial biotechnology. However, their value is frequently compromised by misidentification and undetected microbial contamination. As detailed elsewhere in this volume, the technology, both simple and sophisticated, is available to remedy the problems of misidentification and contamination, given the will to apply it. Combined with proper records of the origin and history of the cell line, assays for authentication and contamination contribute to the provenance of the cell line. Detailed records should start from the initiation or receipt of the cell line, and should incorporate data on the donor as well as the tissue from which the cell line was derived, should continue with details of maintenance, and include any accidental as well as deliberate deviations from normal maintenance. Records should also contain details of authentication and regular checks for contamination. With this information, preferably stored in a database, and suitable backed up, the provenance of the cell line so created makes the cell line a much more valuable resource, fit for validation in industrial applications and more likely to provide reproducible experimental results when disseminated for research in other laboratories. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mouse cell line authentication

The scientific community has responded to the misidentification of human cell lines with validated methods to authenticate these cells; however, few assays are available for nonhuman cell line identification. We have developed a multiplex polymerase chain reaction assay that targets nine tetranucleotide short tandem repeat (STR) markers in the mouse genome. Unique profiles were obtained from seventy-two mouse samples that were used to determine the allele distribution for each STR marker. Correlations between allele fragment length and repeat number were determined with DNA Sanger sequencing. Genotypes for L929 and NIH3T3 cell lines were shown to be stable with increasing passage numbers as there were no significant differences in fragment length with samples of low passage when compared to high passage samples. In order to detect cell line contaminants, primers for two human STR markers were incorporated into the multiplex assay to facilitate detection of human and African green monkey DNA. This multiplex assay is the first of its kind to provide a unique STR profile for each individual mouse sample and can be used to authenticate mouse cell lines.     

Hot line 1

The first Hot line session was a well-attended session, with presentations on several important clinical trials. Chairmen of the session were M. Tendera (Katowice, Poland) and R Gibbons (Rochester, US).     

Funding in the firing line

With large charities such as the Wellcome Trust or the Gates Foundation committed to funding research, is there a risk that politicians could cut public funding for science?Towards the end of 2010, with the British economy reeling from the combined effects of the global recession, the burst bubble of property speculation and a banking crisis, the country came close to cutting its national science and research budget by up to 25%. UK Business Secretary Vince Cable argued, “there is no justification for taxpayers'' money being used to support research which is neither commercially useful nor theoretically outstanding” (BBC, 2010). The outcry from UK scientists was both passionate and reasoned until, in the end, the British budget slashers blinked and the UK government backed down. The Chancellor of the Exchequer, George Osborne, announced in October that the government would freeze science and research funding at £4.6 billion per annum for four years, although even this represents about a 10% cut in real terms, because of inflation.“there is no justification for taxpayers'' money being used to support research which is neither commercially useful nor theoretically outstanding”There has been a collective sigh of relief. Sir John Savill, Chief Executive of the Medical Research Council (UK), said: “The worst projections for cuts to the science budget have not been realised. It''s clear that the government has listened to and acted on the evidence showing investment in science is vital to securing a healthy, sustainable and prosperous future.”Yet Britain is unusual compared with its counterparts elsewhere in the European Union (EU) and the USA, because private charities, such as the Wellcome Trust (London, UK) and Cancer Research UK (London, UK), already have budgets that rival those of their government counterparts. It was this fact, coupled with UK Prime Minister David Cameron''s idea of the ‘big society''—a vision of smaller government, increased government–private partnerships and a bigger role for non-profit organizations, such as single-disease-focused charities—that led the British government to contemplate reducing its contribution to research, relying on the private sector to pick up the slack.Jonathan Grant, president of RAND Europe (London, UK)—a not-for-profit research institute that advises on policy and decision-making—commented: “There was a strong backlash and [the UK Government] pulled back from that position [to cut funding]. But that''s the first time I''ve really ever seen it floated as a political idea; that government doesn''t need to fund cancer research because we''ve got all these not-for-profits funding it.”“…that''s the first time I''ve really ever seen it floated as a political idea; that government doesn''t need to fund cancer research because we''ve got all these not-for-profits funding it”But the UK was not alone in mooting the idea that research budgets might have to suffer under the financial crisis. Some had worried that declining government funding of research would spread across the developed world, although the worst of these fears have not been realized.Peter Gruss, President of the Max Planck Society (Munich, Germany), explained that his organization receives 85% of its more-than €1.5 billion budget from the public purses of the German federal government, German state ministries and the EU, and that not all governments have backed away from their commitment to research. In fact, during the crisis, the German and US governments boosted their funding of research with the goal of helping the economic recovery. In 2009, German Chancellor Angela Merkel''s government, through negotiation with the German state science ministries, approved a windfall of €18 billion in new science funding, to be spread over the next decade. Similarly, US President Barack Obama''s administration boosted spending on research with a temporary stimulus package for science, through the American Recovery and Reinvestment Act.Even so, Harry Greenberg, Senior Associate Dean for Research at Stanford University (California, USA) pointed out that until the US government injected stimulus funding, the budget at the National Institutes of Health (NIH; Bethesda, Maryland, USA) had essentially “been flat as a pancake for five or six years, and that means that it''s actually gone down and it''s having an effect on people being able to sustain their research mission.”Similarly, Gruss said that the research community should remain vigilant. “I think one could phrase it as there is a danger. If you look at Great Britain, there is the Wellcome Trust, a very strong funding organization for life sciences and medical-oriented, health-oriented research. I think it''s in the back of the minds of the politicians that there is a gigantic foundation that supports that [kind of research]. I don''t think one can deny that. There is an atmosphere that people like the Gates family [Bill and Melinda Gates Foundation] invests in health-related issues, particularly in the poorer countries [and that] maybe that is something that suffices.”The money available for research from private foundations and charities is growing in both size and scope. According to Iain Mattaj, Director General of the European Molecular Biology Laboratory (EMBL; Heidelberg, Germany), this growth might not be a bad thing. As he pointed out, private funding often complements government funding, with charities such as the Wellcome Trust going out of their way to leverage government spending without reducing government contributions. “My feeling is that the reason that the UK government is freezing research funding has all to do with economics and nothing to do with the fact that there are potentially private funders,” he said. “Several very large charities in particular are putting a lot of money into health research. The Gates Foundation is the biggest that has just come on the scene, but the Howard Hughes Medical Institute [HHMI; Chevy Chase, Maryland, USA] and the Wellcome Trust are very big, essentially private charities which have their own agendas.”…charities such as the Wellcome Trust [go] out of their way to leverage government spending without reducing government contributions​contributionsOpen in a separate window© CorbisBut, as he explained, these charities actually contribute to the overall health research budget, rather than substituting funds from one area to another. In fact, they often team up to tackle difficult research questions in partnership with each other and with government. Two-thirds of the €140 million annual budget of EMBL comes from the European states that agree to fund it, with additional contributions from private sources such as the Wellcome Trust and public sources such as the NIH.Yet over the years, as priorities have changed, the focus of those partnerships and the willingness to spend money on certain research themes or approaches has shifted, both within governments and in the private sector. Belief in the success of US President Richard Nixon''s famous ‘war on cancer'', for example, has waned over the years, although the fight and the funding continues. “I don''t want to use the word political, because of course the decisions are sometimes political, but actually it was a social priority to fight cancer. It was a social priority to fight AIDS,” Mattaj commented. “For the Wellcome Trust and the Gates Foundation, which are fighting tropical diseases, they see that as a social necessity, rather than a personal interest if you like.”Nevertheless, Mattaj is not surprised that there is an inclination to reduce research spending in the UK and many smaller countries battered by the economic downturn. “Most countries have to reduce public spending, and research is public spending. It may be less badly hit than other aspects of public spending. [As such] it''s much better off than many other aspects of public spending.”A shift away from government funding to private funding, especially from disease-focused charities, worries some that less funding will be available for basic, curiosity-driven research—a move from pure research to ‘cure'' research. Moreover, charities are often just as vulnerable to economic downturns, so relying on them is not a guarantee of funding in harsh economic times. Indeed, greater reliance on private funding would be a return to the era of ‘gentlemen scientists'' and their benefactors (Sidebar A).

Sidebar A | Gentlemen scientists

Greater reliance on private funding would return science to a bygone age of gentlemen scientists relying on the largesse of their wealthy sponsors. In 1831, for example, naturalist Charles Darwin''s (1809–1882) passage on the HMS Beagle was paid for by his father, albeit reluctantly. According to Laura Snyder, an expert on Victorian science and culture at St John''s University (New York, USA), by the time Darwin returned to England in 1836, the funding game had changed and government and private scientific societies had begun to have a bigger role. When Sir John Frederick William Herschel (1791–1871), an English mathematician, astronomer, chemist, experimental photographer and inventor, journeyed to Cape Colony in 1833, the British government offered to give him a free ride aboard an Admiralty ship. “Herschel turned them down because he wanted to be free to do whatever he wanted once he got to South Africa, and he didn''t want to feel beholden to government to do what they wanted him to do,” Snyder explained, drawing from her new book The Philosophical Breakfast Club, which covers the creation of the modern concept of science.Charles Babbage (1791–1871), the mathematician, philosopher, inventor and mechanical engineer who originated the concept of a programmable computer, was a member of the same circle as Herschel and William Whewell (1794–1866), a polymath, geologist, astronomer and theologian, who coined the word ''scientist''. Although he was wealthy, having inherited £100,000 in 1827—valued at about £13.3 million in 2008—Babbage felt that government should help pay for his research that served the public interest.“Babbage was asking the government constantly for money to build his difference engine,” Snyder said. Babbage griped about feeling like a tradesman begging to be paid. “It annoyed him. He felt that the government should just have said, ''We will support the engine, whatever it is that you need, just tell us and we''ll write you a check''. But that''s not what the government was about to do.”Instead, the British government expected Babbage to report on his progress before it loosened its purse strings. Snyder explained, “What the government was doing was a little bit more like grants today, in the sense that you have to justify getting more money and you have to account for spending the money. Babbage just wanted an open pocketbook at his disposal.”In the end the government donated £17,000, and Babbage never completed the machine.Janet Rowley, a geneticist at the University of Chicago, is worried that the change in funding will make it more difficult to obtain money for the kind of research that led to her discovery in the 1970s of the first chromosomal translocations that cause cancer. She calls such work ‘fishing expeditions''. She said that the Leukemia & Lymphoma Society (White Plains, New York, USA), for example—a non-profit funder of research—has modified its emphasis: “They have now said that they are going to put most of their resources into translational work and trying to take ideas that are close to clinical application, but need what are called incubator funds to ramp up from a laboratory to small-scale industrial production to increase the amount of compound or whatever is required to do studies on more patients.”This echoes Vince Cable''s view that taxpayers should not have to spend money on research that is not of direct economic, technological or health benefit to them. But if neither charities nor governments are willing to fund basic research, then who will pay the bill?…if neither charities nor governments are willing to fund basic research, then who will pay the bill?Iain Mattaj believes that the line between pure research and cure research is actually too blurred to make these kinds of funding distinctions. “In my view, it''s very much a continuum. I think many people who do basic research are actually very interested in the applications of their research. That''s just not their expertise,” he said. “I think many people who are at the basic end of research are more than happy to see things that they find out contributing towards things that are useful for society.”Jack Dixon, Vice President and Chief Scientific Officer at HHMI, also thinks that the line is blurry: “This divide between basic research and translational research is somewhat arbitrary, somewhat artificial in nature. I think every scientist I know who makes important, basic discoveries likes to [...] see their efforts translate into things that help humankind. Our focus at the Hughes has always been on basic things, but we love to see them translated into interesting products.” Even so, HHMI spends less than US $1 billion annually on research, which is overshadowed by the $30 billion spent by the NIH and the relatively huge budgets of the Wellcome Trust and Cancer Research UK. “We''re a small player in terms of the total research funding in the US, so I just don''t see the NIH pulling back on supporting research,” Dixon said.By way of example, Brian Druker, Professor of Medicine at the Oregon Health & Science University (Portland, Oregon, USA) and a HHMI scientist, picked up on Rowley''s work with cancer-causing chromosomal translocations and developed the blockbuster anti-cancer drug, imatinib, marketed by Novartis. “Brian Druker is one of our poster boys in terms of the work he''s done and how that is translated into helping people live longer lives that have this disease,” Dixon commented.There is a similar view at Stanford. The distinction between basic and applied is “in the eye of the beholder,” Greenberg said. “Basic discovery is the grist for the mill that leads to translational research and new breakthroughs. It''s always been a little difficult to convey, but at least here at Stanford, that''s number one. Number two, many of our very basic researchers enjoy thinking about the translational or clinical implications of their basic findings and some of them want to be part of doing it. They want some benefit for mankind other than pure knowledge.”“Basic discovery is the grist for the mill that leads to translational research and new breakthroughs”If it had not backed down from the massive cuts to the research budget that were proposed, the intention of the UK Government to cut funding for basic, rather than applied, research might have proven difficult to implement. Identifying which research will be of no value to society is like trying to decide which child will grow up to be Prime Minister. Nevertheless, most would agree that governments have a duty to get value-for-money for the taxpayer, but defining the value of research in purely economic or translational terms is both short-sighted and near impossible. Even so, science is feeling the economic downturn and budgets are tighter than they have been for a long time. As Greenberg concluded, “It''s human nature when everybody is feeling the pinch that you think [yours] is bigger than the next guy''s, but I would be hard pressed to say who is getting pinched, at least in the biomedical agenda, more than who else.”     

A human liposarcoma cell line

Summary The properties of a new cell line derived from a human retroperitoneal liposarcoma are described. The cells do not grow at low cell concentrations and contain in their cytoplasm large numbers of droplets that stain with Oil Red O. No indication of the presence of endogenous virus particles could be found. The mean chromosome number per cell is 36, with several constant markers, the most conspicuous of which is a large submetacentric marker due to a translocation between chromosomes 4 and 11, which is present in every cell. The liposarcoma cells show an enhanced uptake of [¹⁴C]acetate compared to normal human fibroblasts. This work was supported by funds from the Poliomyelitis Research Foundation, the National Cancer Association of South Africa, and the State health Department. The authors thank Mrs. D. Bower and Mrs. M. Orchard for their excellent technical assistance.     

Plant male germ line transformation

A new method to produce transgenic plants - ma le ge rm li ne tr ansformation (MAGELITR) is reported. Unicellular tobacco microspores were isolated from excised anthers, and DNA carrying two marker genes was transferred biolistically. The bombarded microspores were matured in vitro for 6 days, and the mature pollen was used for in vivo pollination. Seeds were recovered and putative transformants were selected on the basis of their antibiotic resistance. Five kanamycin-resistant plants were chosen for further analysis, four contained the first construct, one the second. Parallel experiments with bicellular immature pollen did not produce any transgenic plants. A detailed DNA blot and expression analysis confirmed the transgenic nature of the five plants, and a genetic analysis showed that the transgenes are transmitted to subsequent generations. MAGELITR is a fast, regeneration-independent method, not prone to chimerism and somaclonal variation which should be genotype-independent and may be applicable in a wide range of species once in vitro maturation of pollen is established.     

On a front line.

Like the patients, doctors in Sarajevo depend largely on humanitarian aid; everyone in the public sector has worked without pay for almost three years. The hospital is on a front line; yet the psychiatric department continues to function, even conducting large scale studies of psychosocial aspects of war in Bosnia-Hercegovina. The type of inpatient morbidity and treatment patterns have changed. A plethora of psychosocial rehabilitation programmes has emerged, including counselling, drop in centres, and attending to special needs of elderly people, schoolchildren, and women. The most prominent psychological symptoms were exhaustion at the prospect of a third winter of war and bewilderment at the Western stereotype of Bosnians as Muslim fundamentalists.     

Automation of cell line development

An automated platform for development of high producing cell lines for biopharmaceutical production has been established in order to increase throughput and reduce development costs. The concept is based on the Cello robotic system (The Automation Partnership) and covers screening for colonies and expansion of static cultures. In this study, the glutamine synthetase expression system (Lonza Biologics) for production of therapeutic monoclonal antibodies in Chinese hamster ovary cells was used for evaluation of the automation approach. It is shown that the automated procedure is capable of producing cell lines of equal quality to the traditionally generated cell lines in terms of colony detection following transfection and distribution of IgG titer in the screening steps. In a generic fed-batch evaluation in stirred tank bioreactors, IgG titers of 4.7 and 5.0 g/L were obtained for best expressing cell lines. We have estimated that the number of completed cell line development projects can be increased up to three times using the automated process without increasing manual workload, compared to the manual process. Correlation between IgG titers obtained in early screens and titers achieved in fed-batch cultures in shake flasks was found to be poor. This further implies the benefits of utilizing a high throughput system capable of screening and expanding a high number of transfectants. Two concentrations, 56 and 75 μM, of selection agent, methionine sulphoximine (MSX), were applied to evaluate the impact on the number of colonies obtained post transfection. When applying selection medium containing 75 μM MSX, fewer low producing transfectants were obtained, compared to cell lines selected with 56 μM MSX, but an equal number of high producing cell lines were found. By using the higher MSX concentration, the number of cell line development projects run in parallel could be increased and thereby increasing the overall capacity of the automated platform process. A. Salmén and K. Lindgren contributed equally to the work.     

Long-term-cultured mouse B-lymphocyte line. II. Modulation of Ia-antigen expression on B-lymphocyte line

Mouse B-cell line, established by culturing anti-Thy-1 and complement-treated splenic B cells with concanavalin A-stimulated conditioned medium, expressed immunoglobulins and Ia antigens on its surface. The long-term-cultured B-cell line was split in two and maintained with or without 3300 R X-irradiated T-cell-depleted syngeneic splenic adherent cells (SAC). Interestingly, the B-cell line cultured without SAC lost its Ia antigen but not its Ig expression, whereas the cell line with SAC maintained both Ia and Ig expression. The ability to express Ia antigens was restored by culturing them only in the presence of Ia-positive feeder cells. Neither recombinant interferon-gamma or lectin-stimulated conditioned medium nor cell-free culture supernatant SAC had the ability to restore Ia antigen expression on the B-cell line. Incubation of Ia-negative B-cell line with phorbol esters restored the Ia expression. It is suggested that the expression of Ia antigen on B lymphocytes was controlled differently from that on macrophage lineage. The B-cell line expressing Ia antigens acts as stimulator cells for alloantigen-activated T lymphocytes and as antigen-presenting cells on the KLH-specific Ia-restricted proliferative T-cell clone in the presence of a specific antigen.     

Microsporogenesis in a normal line and in the ogu cytoplasmic male-sterile line of Brassica napus

Summary In the ogu cytoplasmic male-sterile (CMS) line of Brassica napus, stamen morphology was influenced by temperature conditions. Under a high temperature regime (27° C/23° C; day/ night) CMS stamens had a near-normal morphology, but microsporogenesis proceeded to a maximum of the microspore stage. However, compared to the normal stamens, the occurrence of sporopollenin-like deposits in the tapetum and deposition of exine on the microspores was sparse. Also, the tapetal cells of the CMS line were often highly vacuolate and failed to degenerate at the same stage as the normal. Ultrastructural changes in the mitochondrial matrix and cristae plus dilation of the endoplasmic reticulum, which occurred during development in sporogenous tissues of the normal line, were often lacking or mistimed in the mutant. Due to extensive variation, even between adjacent locules, the cytological differences between the normal and CMS anthers cannot be ascribed as the cause of male sterility in the ogu CMS line of B. napus, rather they may be the consequence of it.     

染色体C-带在小麦—黑麦易位系和代换系鉴定中的作用

用改良的Giemsa C-带技术对10个经辐射处理的带有黑麦某些性状的普通小麦品系进行鉴定。结果鉴定出1个小麦—黑麦易位系及2个小麦—黑麦异代换系,探索出冬季和夏季染色体分带的不同条件。因此,只要条件控制得当,C-分带不失为一种快速、精确而经济的鉴定外源染色体的方法。     

Parallel recognition of idealised line characters

Summary The aim is to design a machine which is able to learn a number of idealised characters and to recognise them, irrespective of their size, position and context on an infinite retina. If the number of characters which such a machine can possibly learn to recognise is astronomical, it is not practical to use separate templates for every possible character. It is more economical to use, instead, templates for various parts, called features, of characters. In recognising a number of characters simultaneously, without scanning, the question arises of how to tell which feature belongs to which character of figure on the retina. In particular, if a given character is not present but all its features are included in nonsense figures simultaneously present on the retina then the machine must not indicate the presence of the given character. The technique which overcomes this difficulty employs overlapping features which must be mutually consistent for recognition. This consistency technique is assessed by comparison with a more conventional technique, and the work is restricted to closed line characters which are not subject to deformations or mutilations.     

Hot line III

New data from several landmark trials were presented during the third hot line session on clinical trial updates, which was chaired by N. Danchin (Paris, France) and E. Braunwald (Boston, US)     

Development of the zebrafish lateral line

The lateral line system is simple (comprising six cell types), its sense organs form according to a defined and reproducible pattern, and its neurons are easily visualized. In the zebrafish, these advantages can be combined with a wealth of genetic tools, making this system ideally suited to a combined molecular, cellular and genetic analysis. Recent progress has taken advantage of these various qualities to elucidate the mechanism that drives the migration from head to tail of the sense organ precursor cells, and to approach the questions surrounding axonal guidance and target recognition.     

Adaptive line transect sampling

Adaptive line transect sampling offers the potential of improved population density estimation efficiency over conventional line transect sampling when populations are spatially clustered. In adaptive sampling, survey effort is increased when areas of high animal density are located, thereby increasing the number of observations. Its disadvantage is that the survey effort required is not known in advance. We develop an adaptive line transect methodology that, by varying the degree of adaptation, allows total effort to be fixed at the design stage. Relative to conventional line transect surveys, it also provides better survey coverage in the event of disruption in survey effort, e.g., due to poor weather. In analysis, sightings from the adaptive sections are downweighted in proportion to the increase in effort. We evaluate the methodology by simulation and report on surveys of harbor porpoise in the Gulf of Maine, in which the approach was compared with conventional line transect sampling.     

Telomerase-transduced osteoarthritic fibroblast-like synoviocyte cell line

To examine whether the life span of fibroblast-like synoviocytes (FLSs) can be extended and to establish FLS cell lines that preserve the characteristics of primary FLSs, we introduced human catalytic subunit of telomerase (hTERT) gene into human osteoarthritic (OA) FLSs. Two hTERT-transduced clonal cell lines were established and one line, hTERT-OA FLS 13A, was characterized. The hTERT-OA FLS 13A cells have a morphology similar to that of the parental untransduced cells and a population-doubling time similar to that of the parental cells of early passages. While the parental untransduced OA FLSs reached senescence after 100 days in culture, the hTERT-OA FLS 13A cells continued to grow at a population-doubling rate of once in about every 2-3 days. The hTERT-OA 13A cells have so far grown in culture beyond 450 days and maintained the same growth rate. Furthermore, the hTERT-OA FLS 13A cells preserved their sensitivity and response to the treatment with basic calcium phosphate crystals and interleukin-1beta. In conclusion, exogenous expression of telomerase represents a way to extend the life span of human FLSs and telomerase-transduced FLS cells offer a promising tool for gene regulation, cell-based assay, cell transplantation-based gene therapy, and tissue engineering research and development.     

Hot line II

Five studies were presented during this session regarding treatment of patients with acute coronary syndrome (ACS) with or without ST elevation, patients undergoing elective percutaneous interventions, and patients undergoing percutaneous peripheral arterial interventions. The session was chaired by C.W. Hamm (Bad Nauheim, Germany) and J.P. Bassand (Besancon, France).     

Sequential estimation in line transect surveys

This article considers using sequential procedures to determine the amount of survey effort required in a line transect survey in order to achieve a certain precision level in estimating the abundance of a biological population. Sequential procedures are constructed for both parametric and nonparametric animal abundance estimators. The criterion used to derive the stopping rules is the width of confidence intervals for the animal abundance. For each estimator considered, we develop stopping rules based on the asymptotic distributions and the bootstrap. A sequential analysis on an aerial survey of the southern bluefin tuna indicates substantial saving of survey effort can be made by employment of the proposed sequential procedures. This savings of survey effort is also observed in a simulation study designed to evaluate the empirical performance of the proposed sequential procedures.