Al/SiC carriers for microwave integrated circuits by a new technique of pressureless infiltration

Materials with high thermal conductivity and thermal expansion coefficient matching with that of Si or GaAs are being used for packaging high density microcircuits due to their ability of faster heat dissipation. Al/SiC is gaining wide acceptance as electronic packaging material due to the fact that its thermal expansion coefficient can be tailored to match with that of Si or GaAs by varying the Al:SiC ratio while maintaining the thermal conductivity more or less the same. In the present work, Al/SiC microwave integrated circuit (MIC) carriers have been fabricated by pressureless infiltration of Al-alloy into porous SiC preforms in air. This new technique provides a cheaper alternative to pressure infiltration or pressureless infiltration in nitrogen in producing Al/SiC composites for electronic packaging applications. Al-alloy/65vol% SiC composite exhibited a coefficient of thermal expansion of 7 x 10(-6) K-1 (25 degrees C-100 degrees C) and a thermal conductivity of 147 Wm(-1) K-1 at 30 degrees C. The hysteresis observed in thermal expansion coefficient of the composite in the temperature range 100 degrees C-400 degrees C has been attributed to the presence of thermal residual stresses in the composite. Thermal diffusivity of the composite measured over the temperature range from 30 degrees C to 400 degrees C showed a 55% decrease in thermal diffusivity with temperature. Such a large decrease in thermal diffusivity with temperature could be due to the presence of micropores, microcracks, and decohesion of the Al/SiC interfaces in the microstructure (all formed during cooling from the processing temperature). The carrier showed satisfactory performance after integrating it into a MIC.

Models of Dispersal and Diversification

Ecology and evolutionary biology is the study of life on this planet. One of the many methods applied to answering the great diversity of questions regarding the lives and characteristics of individual organisms, is the utilization of mathematical models. Such models are used in a wide variety of ways. Some help us to reason, functioning as aids to, or substitutes for, our own fallible logic, thus making argumentation and thinking clearer. Models which help our reasoning can lead to conceptual clarification; by expressing ideas in algebraic terms, the relationship between different concepts become clearer. Other mathematical models are used to better understand yet more complicated models, or to develop mathematical tools for their analysis. Though helping us to reason and being used as tools in the craftmanship of science, many models do not tell us much about the real biological phenomena we are, at least initially, interested in. The main reason for this is that any mathematical model is a simplification of the real world, reducing the complexity and variety of interactions and idiosynchracies of individual organisms. What such models can tell us, however, both is and has been very valuable throughout the history of ecology and evolution. Minimally, a model simplifying the complex world can tell us that in principle, the patterns produced in a model could also be produced in the real world. We can never know how different a simplified mathematical representation is from the real world, but the similarity models do strive for, gives us confidence that their results could apply. This thesis deals with a variety of different models, used for different purposes. One model deals with how one can measure and analyse invasions; the expanding phase of invasive species. Earlier analyses claims to have shown that such invasions can be a regulated phenomena, that higher invasion speeds at a given point in time will lead to a reduction in speed. Two simple mathematical models show that analysis on this particular measure of invasion speed need not be evidence of regulation. In the context of dispersal evolution, two models acting as proof-of-principle are presented. Parent-offspring conflict emerges when there are different evolutionary optima for adaptive behavior for parents and offspring. We show that the evolution of dispersal distances can entail such a conflict, and that under parental control of dispersal (as, for example, in higher plants) wider dispersal kernels are optimal. We also show that dispersal homeostasis can be optimal; in a setting where dispersal decisions (to leave or stay in a natal patch) are made, strategies that divide their seeds or eggs into fractions that disperse or not, as opposed to randomized for each seed, can prevail. We also present a model of the evolution of bet-hedging strategies; evolutionary adaptations that occur despite their fitness, on average, being lower than a competing strategy. Such strategies can win in the long run because they have a reduced variance in fitness coupled with a reduction in mean fitness, and fitness is of a multiplicative nature across generations, and therefore sensitive to variability. This model is used for conceptual clarification; by developing a population genetical model with uncertain fitness and expressing genotypic variance in fitness as a product between individual level variance and correlations between individuals of a genotype. We arrive at expressions that intuitively reflect two of the main categorizations of bet-hedging strategies; conservative vs diversifying and within- vs between-generation bet hedging. In addition, this model shows that these divisions in fact are false dichotomies.

Bacteria colonizing paper machines

Bacteria growing in paper machines can cause several problems. Biofilms detaching from paper machine surfaces may lead to holes and spots in the end product or even break the paper web leading to expensive delays in production. Heat stable endospores will remain viable through the drying section of paper machine, increasing the microbial contamination of paper and board. Of the bacterial species regularly found in the end products, Bacillus cereus is the only one classified as a pathogen. Certain B. cereus strains produce cereulide, the toxin that causes vomiting disease in food poisonings connected to B. cereus. The first aim of this thesis was to identify harmful bacterial species colonizing paper machines and to assess the role of bacteria in the formation of end product defects. We developed quantitative PCR methods for detecting Meiothermus spp. and Pseudoxanthomonas taiwanensis. Using these methods I showed that Meiothermus spp. and Psx. taiwanensis are major biofoulers in paper machines. I was the first to be able to show the connection between end product defects and biofilms in the wet-end of paper machines. I isolated 48 strains of primary-biofilm forming bacteria from paper machines. Based on one of them, strain K4.1T, I described a novel bacterial genus Deinobacterium with Deinobacterium chartae as the type species. I measured the transfer of Bacillus cereus spores from packaging paper into food. To do this, we constructed a green fluorescent protein (GFP) labelled derivative of Bacillus thuringiensis and prepared paper containing spores of this strain. Chocolate and rice were the recipient foods when transfer of the labelled spores from the packaging paper to food was examined. I showed that only minority of the Bacillus cereus spores transferred into food from packaging paper and that this amount is very low compared to the amount of B. cereus naturally occurring in foods. Thus the microbiological risk caused by packaging papers is very low. Until now, the biological function of cereulide for the producer cell has remained unknown. I showed that B. cereus can use cereulide to take up K+ from environment where K+ is scarce: cereulide binds K+ ions outside the cell with high affinity and transports these ions across cell membrane into the cytoplasm. Externally added cereulide increased the growth rate of cereulide producing strains in medium where potassium was growth limiting. In addition, cereulide producing strains outcompeted cereulide non-producing B. cereus in potassium deficient environment, but not when the potassium concentration was high. I also showed that cereulide enhances biofilm formation of B. cereus.

Ruokauskomukset Mosambikin maaseudun raskaana olevilla ja imettävillä naisilla

Ihmisille ympäri maailmaa on tyypillistä valita tiettyjä ruokia suuremmasta valikoimasta syömäkelpoista ruokaa ja luoda mieltymyksiä sekä kieltoja joitakin ruokia kohtaan. Näitä ilmiöitä kutsutaan ruokauskomuksiksi ja ne ovat tärkeä osa kulttuuria. Niiden taustalla on usein terveydelliset perustelut tai sosiaalinen arvostus yhteisössä. Afrikassa on todettu olevan paljon erilaisia ruokauskomuksia, jotka kohdistuvat usein raskaana oleviin ja imettäviin naisiin sekä lapsiin, ryhmään, joka on fysiologisesti erityisen herkässä elämänvaiheessa. Ravitsemustilan tai ruokaturvan ollessa heikko, mahdollisilla ruokauskomuksilla voi olla merkittävät seuraukset erityisesti tämän väestönosan terveydentilaan. Aliravitsemus ja virheravitsemus ovat edelleen suuria ongelmia Afrikassa ja muissa kehittyvissä maissa. Tämän työn tavoitteena oli tutkia laadullisin menetelmin, onko erityisesti raskaana olevilla ja imettävillä naisilla Keski-Mosambikin maaseudulla, Zambézian maakunnassa, ruokauskomuksia, mitä ne mahdollisesti ovat, sekä arvioida voiko ruokauskomuksilla olla ravitsemuksellista merkitystä. Menetelminä oli 5 ryhmähaastattelua kolmessa kylässä ja 10 yksilöhaastattelua kahdessa kylässä. Tutkittavat olivat 12–78-vuotiaita naisia ja heitä oli yhteensä 27. Tulkkaus, tutkimusaiheen sensitiivisyys ja haastattelijan kokemattomuus aiheuttivat haasteita haastatteluiden toteutukseen. Tämän vuoksi menetelmää muokattiin ja se vaihdettiin ryhmähaastattelusta yksilöhaastatteluun tutkimuksen aikana. Ruokauskomukset vaihtelivat sekä kylien välillä että kylien sisällä, joskin niistä löytyi samantyyppisiä pääpiirteitä. Työssä todettiin, että raskaana oleviin ja imettäviin naisiin kohdistui tutkimusalueella ruokauskomuksia. Raskauden aikana tuli välttää pääasiassa proteiinipitoisia ruokia, kuten lihaa ja kalaa ja puolestaan suosia kasvisten, hedelmien ja viljatuotteiden käyttöä. Linnun munien syöntiä sekä suositeltiin että kehotettiin välttämään raskauden aikana. Raskauden aikana ilmeni lisäksi tietoinen tapa vähentää kassavapuuron tai ruuan syömistä kokonaisuudessaan. Imetyksen aikana ei vältetty juuri mitään ruokia, vaan suositeltiin kookosta ja kasviksia. Suurin osa perusteluista liittyi äidin ja lapsen terveyteen. Perustelut voitiin jakaa seuraaviin ryhmiin: lisää äidinmaidon tuotantoa; aiheuttaa vatsakipua äidillä; pitää yllä kuntoa ja estää vatsan kasvua; äidistä tulee vahva, terve ja hän saa vitamiineja; lapsen ulkonäkö muuttuu; lapsesta tulee terve ja vahva; lapsen käyttäytyminen muuttuu; aiheuttaa keskenmenon; aiheuttaa vaikean tai helpon synnytyksen. Ruokauskomukset ja terveysviranomaisilta tullut valistus oli osittain sekoittunut keskenään. Lähes kaikki naiset kertoivat noudattavansa näitä ruokauskomuksia. Muutamat naiset kertoivat suositeltavien ruokien kohdalla, että ruokien saatavuus tekee noudattamisen joskus vaikeaksi. Proteiinipitoisten ruokien välttäminen voi lisätä proteiinialiravitsemuksen riskiä ja syömisen vähentäminen saattaa lisätä riskiä saada riittämättömästi energiaa raskauden aikana. Suositeltavat ruuat todennäköisesti edistävät terveyttä. Tutkielman perusteella voitiin todeta, että vieraassa kulttuurissa tutkiminen vaatii tutkimusmenetelmältä paljon. Tärkeää on menetelmän joustavuus, jotta sitä voi muuttaa tutkimuskentällä toimivampaan ja luotettavampaan muotoon. Johtopäätöksenä todettiin, että suositeltavin menetelmä tutkittaessa ruokauskomuksia tällä tutkimusalueella olisi ollut yksilöhaastattelut, jossa olisi ollut mahdollisimman vähän osallistujia ja osallistujat olisivat olleet samaa sukupuolta ja saman ikäisiä. Terveyden ja ravitsemuksen kannalta on tärkeää, että ruokauskomuksista ollaan tietoisia ja väestön ruokauskomuksia tutkitaan alueittain, koska ne voivat vaihdella merkittävästi jopa kylien tai ihmisryhmien sisällä.

Novel reproductive mode in a torrent frog Micrixalus saxicola (Jerdon) from the Western Ghats, India

Reproductive modes in anurans are highly diverse despite external fertilization being a constraint. There are 39 reproductive modes documented so far (Wells, 2007). An apparently new reproductive mode is reported in a torrent frog, Micrixalus saxicola, an endemic and ancient anuran frog of the Western Ghats, considering the type of cavity made inside the lotic water body, involvement of the female in digging the cavity and concealing the eggs.

Theoretical and Experimental Studies on an Ammonia-Based Loop Heat Pipe With a Flat Evaporator

An ammonia loop heat pipe (LHP) with a flat plate evaporator is developed and tested. The device uses a nickel wick encased in an aluminum-stainless steel casing. The loop is tested for various heat loads and different sink temperatures, and it demonstrated reliable startup characteristics. Results with the analysis of the experimental observation indicate that the conductance between the compensation chamber and the heater plate can significantly influence the operating temperatures of the LHP. A mathematical model is also presented which is validated against the experimental observations.

How do heterogametic females survive without gene dosage compensation?

When the male is the heterogametic sex (XX♀-XY♂ or XX♀-XO♂), as inDrosophila, orthopteran insects, mammals andCaenorhabditis elegans, X-linked genes are subject to dosage compensation: the single X in the male is functionally equivalent to the two Xs in the female. However, when the female is heterogametic (ZZ♂-ZW♀), as in birds, butterflies and moths, Z-linked genes are apparently not dosage-compensated. This difference between X-linked and Z-linked genes raises fundamental questions about the role of dosage compensation. It is argued that (i) genes which require dosage compensation are primarily those that control morphogenesis and the prospective body plan; (ii) the products of these genes are required in disomic doses especially during oogenesis and early embryonic development; (iii) heterogametic females synthesize and store during oogenesis itself morphogenetically essential gene products - including those encoded by Z-linked genes — in large quantities; (iv) the abundance of these gene products in the egg and their persistence relatively late into embryogenesis enables heterogametic females to overcome the monosomic state of the Z chromosome in ZW embryos. Female heterogamety is predominant in birds, reptiles and amphibians, all of which have megalecithal eggs containing several thousand times more maternal RNA and other maternal messages than eggs of mammals,Caenorhabditis elegans, orDrosophila. This increase in egg size, yolk content and, concomitantly, the size of the maternal legacy to the embryo, may have facilitated female heterogamety and the absence of dosage compensation.

Seasonal variation in the onset of egg laying in a primitively eusocial wasp: implications for the evolution of sociality

When freshly eclosed females of the primitively eusocial wasp, Rapalidia marginata are isolated into individual cages, only about half of them build nests and lay eggs and those that do so take a long and variable amount of time (Mean +/- SD = 66 +/- 37 days) before they lay their first egg. Part of the reason for this delay is because, when kept in isolation, no wasp begins to lay eggs during a period of approximately 82 days from mid - October to early January. Wasps maintained at a constant temperature of 26 +/- 1-degrees-C however initiate egg laying throughout the year, suggesting that the low temperatures during mid - October to early January may be at least one factor that makes this period unfavourable for wasps maintained at room temperature. Egg laying continues more or less normally throughout October-January however, in all natural and laboratory colonies studied. Natural colonies of R. marginata are initiated throughout the year and often by groups of females. Huddling together is a striking feature of the wasps especially on cold mornings. We therefore suggest that the isolated animals in our experiment are unable to lay eggs during the coldest part of the year because of their inability to huddle together, share metabolic heat and perform "co-operative thermoregulation". Such "co-operative thermoregulation" may thus be another factor that facilitates the evolution of socialitly.

The role of larval nutrition in pre-imaginal biasing of caste in the primitively eusocial wasp Ropalidia marginata (Hymenoptera: Vespidae)

1. When freshly eclosed females of the primitively eusocial wasp Ropalidia marginata (Lep.) are isolated, only about 50% of them build nests and lay eggs thereby suggesting a pre-imaginal biasing of caste. 2. Wasps that lay eggs take a very variable amount of time after eclosion to start doing so. 3. Females eclosing from nests where larvae are fed at a relatively higher rate are more likely to become egg-layers and are likely to take less time after eclosion to begin to lay eggs. 4. Thus, both forms of pre-imaginal biasing of caste, namely, differences in egg laying capacity and differences in the time taken to attain reproductive maturity, appear to be influenced by larval nutrition.

The Transcriptional Regulation of Retrotransposon BARE

The purpose of this research project was to understand the steps of the retrotransposon BARE (BArley REtrotransposon) life cycle, from regulation of transcription to Virus-Like Particle (VLP) formation and ultimate integration back into the genome. Our study concentrates mainly on BARE1 transcriptional regulation because transcription is the crucial first step in the retrotransposon life cycle. The BARE element is a Class I LTR (Long Terminal Repeat) retrotransposon belonging to the Copia superfamily and was originally isolated in our research group. The LTR retrotransposons are transcribed from promoters in the LTRs and encode proteins for packaging of their transcripts, the reverse transcription of the transcripts into cDNA, and integration of the cDNA back into the genome. BARE1 is translated as a single polyprotein and cleaved into the capsid protein (GAG), integrase (IN), and reverse transcriptase-RNaseH (RT-RH) by the integral aspartic proteinase (AP). The BARE retrotransposon family comprises more than 104 copies in the barley (Hordeum vulgare) genome. The element is bound by long terminal repeats (LTRs, 1829 bp) containing promoters required for replication, signals for RNA processing, and motifs necessary for the integration of the cDNA. Members of the BARE1 subfamily are transcribed, translated, and form virus-like particles. Several basic questions concerning transcription are explored in the thesis: BARE1 transcription control, promoter choice in different barley tissues, start and termination sites for BARE transcripts, and BARE1 transcript polyadenylation (I). Polyadenylation is an important step during mRNA maturation, and determines its stability and translatability among other characteristics. Our work has found a novel way used by BARE1 to make extra GAG protein, which is critical for VLP formation. The discovery that BARE1 uses one RNA population for protein synthesis and another RNA population for making cDNA has established the most important step of the BARE1 life cycle (III). The relationship between BARE1 and BARE2 has been investigated. Besides BARE, we have examined the retrotransposon Cassandra (II), which uses a very different transcriptional mechanism and a fully parasitic life cycle. In general, this work is focused on BARE1 promoter activity, transcriptional regulation including differential promoter usage and RNA pools, extra GAG protein production and VLP formation. The results of this study give new insights into transcription regulation of LTR retrotransposons.

Hantavirus infection: Insights into entry, assembly and pathogenesis

Hantaviruses (family Bunyaviridae, genus Hantavirus) are enveloped viruses incorporating a segmented, negative-sense RNA genome. Each hantavirus is carried by its specific host, either a rodent or an insectivore (shrew), in which the infection is asymptomatic and persistent. In humans, hantaviruses cause Hemorrhagic fever with renal syndrome (HFRS) in Eurasia and Hantavirus cardiopulmonary syndrome (HCPS) in the Americas. In Finland, Puumala virus (genus Hantavirus) is the causative agent of NE, a mild form of HFRS. The HFRS-type diseases are often associated with renal failure and proteinuria that might be mechanistically explained by infected kidney tubular cell degeneration in patients. Previously, it has been shown that non-pathogenic hantavirus, Tula virus (TULV), could cause programmed cell death, apoptosis, in cell cultures. This suggested that the infected kidney tubular degeneration could be caused directly by virus replication. In the first paper of this thesis the molecular mechanisms involved in TULV-induced apoptosis was further elucidated. A virus replication-dependent down-regulation of ERK1/2, concomitantly with the induced apoptosis, was identified. In addition, this phenomenon was not restricted to TULV or to non-pathogenic hantaviruses in general since also a pathogenic hantavirus, Seoul virus, could inhibit ERK1/2 activity. Hantaviruses consist of membrane-spanning glycoproteins Gn and Gc, RNA-dependent RNA polymerase (L protein) and nucleocapsid protein N, which encapsidates the viral genome, and thus forms the ribonucleoprotein (RNP). Interaction between the cytoplasmic tails of viral glycoproteins and RNP is assumed to be the only means how viral genetic material is incorporated into infectious virions. In the second paper of this thesis, it was shown by immunoprecipitation that viral glycoproteins and RNP interact in the purified virions. It was further shown that peptides derived from the cytoplasmic tails (CTs) of both Gn and Gc could bind RNP and recombinant N protein. In the fourth paper the cytoplamic tail of Gn but not Gc was shown to interact with genomic RNA. This interaction was probably rather unspecific since binding of Gn-CT with unrelated RNA and even single-stranded DNA were also observed. However, since the RNP consists of both N protein and N protein-encapsidated genomic RNA, it is possible that the viral genome plays a role in packaging of RNPs into virions. On the other hand, the nucleic acid-binding activity of Gn may have importance in the synthesis of viral RNA. Binding sites of Gn-CT with N protein or nucleic acids were also determined by peptide arrays, and they were largely found to overlap. The Gn-CT of hantaviruses contain a conserved zinc finger (ZF) domain with an unknown function. Some viruses need ZFs in entry or post-entry steps of the viral life cycle. Cysteine residues are required for the folding of ZFs by coordinating zinc-ions, and alkylation of these residues can affect virus infectivity. In the third paper, it was shown that purified hantavirions could be inactivated by treatment with cysteine-alkylating reagents, especially N-ethyl maleimide. However, the effect could not be pin-pointed to the ZF of Gn-CT since also other viral proteins reacted with maleimides, and it was, therefore, impossible to exclude the possibility that other cysteines besides those that were essential in the formation of ZF are required for hantavirus infectivity.

Inhibitory effects of wood extracts on the spoilage flora of marinated poultry meat

Polyphenolic compounds occurring naturally in knotwood of plants are known to have antimicrobial effects. The knots (i.e. the branch bases inside tree stems) and outer branches in pine trees contain a remarkably high concentration of phenolic stilbenes, while lignans are the major phenolic constituents of spruce knots. Large amount of these phenolic compounds can be extracted from wood knots at pulp and paper mills where their presence is undesirable. In Finland, marinating of broiler meat is done not only to increase or add value to the meat, but also to enhance the safety and shelf-life. These products are usually packed under a modified atmosphere for further protection against spoilage microorganisms. However, studies have revealed that addition of marinades to poultry products do not have an inhibitory effect on either some psychrotrophic anaerobic bacteria, such as Brochothrix thermosphacta or lactic acid bacteria associated with spoilage. Also, the activity of pathogenic Campylobacter jejuni is not affected by marinating. The objective of this study was to investigate the inhibitory and lethal activities of extracts from spruce (Picea spp.) and pine (Pinus spp.) knotwood and outer branches that are dissolved in ethanol against the spoilage microorganisms in modified atmosphere packaged marinated broiler products. Modified atmosphere packaged broiler products were separately inoculated with ‘normal’ marinades, marinades with 70% ethanol, marinades with a mixture of spruce and pine extracts dissolved in 70% ethanol or mixture of spruce and pine extracts in powder form. The bacterial colony forming units per gram obtained from each of the samples were analysed on de Man Rogosa and Sharpe agar at days 1, 6, 12 and 15. The results showed that there were significant differences in bacterial colony forming units per gram (P <0.05) between packages with ‘normal’ marinades and packages with extracts added to their marinades on the 12th and 15th day. It can be concluded that the addition of extracts from spruce and pine knotwood to marinades significantly retarded growth of spoilage microorganisms during the 15 day test period. However further research is warranted to characterise and establish the safety and suitability of the compound(s) in spruce and pine knotwood extracts that are responsible for inhibitory or lethal activity against the microbes that may be present in marinated poultry meat.

Electrical Contact Resistance in Thin (<= 0.5 mu m) Gold Plated Contacts: Effect of Gold Plating Thickness

This paper describes the electrical contact resistance (ECR) measurements made on thin gold plated (gold plating of <= 0.5 mu m with a Ni underlayer of similar to 2 mu m) oxygen free high conductivity (OFHC) Cu contacts in vacuum environment. ECR in gold plated OFHC Cu contacts is found to be slightly higher than that in bare OFHC Cu contacts. Even though gold is a softer material than copper, the relatively high ECR values observed in gold plated contacts are mainly due to the higher hardness and electrical resistivity of the underlying Ni layer. It is well known that ECR is directly related to plating factor, which increases with increasing coating thickness when the electrical resistivity of coating material is more than that of substrate. Surprisingly, in the present case it is found that the ECR decreases with increasing gold layer thickness on OFHC Cu substrate (gold has higher electrical resistivity than OFHC Cu). It is analytically demonstrated from the topography and microhardness measurements results that this peculiar behavior is associated with thin gold platings, where the changes in surface roughness and microhardness with increasing layer thickness overshadow the effect of plating factor on ECR.

Expression of microinjected foreign DNA in silkworm,bombyx mori

As a prelude to achieving transgenesis in Bombyx mori, conditions have been established for successful microinjection of cloned foreign genes into the silk worm eggs. A sharpened metallic needle is used to pierce the thick chorion layer of the eggsheil, approaching through a droplet of DNA solution deposited on its surface. The microinjection is carried out within 2-2.5 h after oviposition and the injected eggs show 3-5% hatchability and 80-90% survival. Such larvae continuously expressed the microinjected cloned reporter gene, beta-galactosidase, placed under the control of a constitutively expressed cytoplasmic actin A3 gene promoter from B. mori. The expression is seen in different tissues, viz. the fat body, tracheae and the silk glands, till the late larval instars. The microinjected DNA sequences are retained in the adult G(o) moths.

Vitellins and vitellogenins of Dysdercus koenigii (Heteroptera : Pyrrhocoridae) - identification, purification and temporal pattern

Two vitellins, VtA and VtB, were purified from the eggs of Dysdercus koenigii by gel filtration and ion exchange chromatography. VtA and VtB have molecular weights of 290 and 260 kDa, respectively. Both Vts are glycolipoproteinaceous in nature. VtA is composed of three polypeptides of M-r 116, 92 and 62 kDa while VtB contained an additional subunit of M-r 40 kDa. All subunits except the 116-kDa subunit are glycolipopolypeptides. Polyclonal antibody raised against VtA (anti-VtA antibody) cross-reacted with VtB and also with vitellogenic haemolymph and ovaries and pre-vitellogenic fat bodies, but not with haemolymph from either adult male, fifth instar female, or pre-vitellogenic females demonstrating sex and stage specificity of the Vts. Immunoblots in the presence of anti-VtA revealed two proteins (of 290 and 260 kDa) in both vitellogenic haemolymph and pre-vitellogenic fat bodies that are recognised as D. koenigii Vgs. In newly emerged females, Vgs appeared on day 1 in fat bodies and on day 3 in haemolymph and ovaries. Vg concentration was maximum on day 2 in fat body, day 4 in haemolymph and day 7 in ovary. Although the biochemical and temporal characteristics of these proteins show similarity to some hemipterans, they are strikingly dissimilar with those of a very closely related species. (C) 1999 Elsevier Science Inc. All rights reserved.