Cuticular Epithelium Research Articles

Anatomical, histochemical, and developmental approaches reveal the long-term functioning of the floral nectary in Tocoyena formosa (Rubiaceae).

Tocoyena formosa has a persistent floral nectary that continues producing nectar throughout flower and fruit development. This plant also presents an intriguing non-anthetic nectary derived from early-developing floral buds with premature abscised corolla. In this study, we characterize the structure, morphological changes, and functioning of T. formosafloralnectary at different developmental stages. We subdivided the nectary into four categories based on the floral and fruit development stage at which nectar production started: (i) non-anthetic nectary; (ii) anthetic nectary, which follows the regular floral development; (iii) pericarpial nectary, derived from pollinated flowers following fruit development; and (iv) post-anthetic nectary that results from non-pollinated flowers after anthesis. The nectary has a uniseriate epidermis with stomata, nectariferous parenchyma, and vascular bundles, with a predominating phloem at the periphery. The non-anthetic nectary presents immature tissues that release the exudate. The nectary progressively becomes more rigid as the flower and fruit develop. The main nectary changes during flower and fruit development comprised the thickening of the cuticle and epidermal cell walls, formation of cuticular epithelium, and an increase in the abundance of calcium oxalate crystals and phenolic cells near the vascular bundles. Projections of the outer periclinal walls toward the cuticle in the post-anthetic nectary suggest nectar reabsorption. The anatomical changes of the nectary allow it to function for an extended period throughout floral and fruit development. Hence, T. formosa nectary is a bivalent secretory structure that plays a crucial role in the reproductive and defensive interactions of this plant species.

Variation in Paramarteilia canceri infections in velvet crab Necora puber.

Sustainable management of crustacean populations requires an understanding of the range of factors affecting different crustacean species. Recently, a high prevalence of a paramyxid parasite, Paramarteilia canceri, was reported in velvet crabs Necora puber in Ireland. Similar parasites have been known to cause mass mortalities in bivalves and, as velvet crabs are an important commercial species, these parasite infections are cause for concern. The main objective of this study was to examine variation in P. canceri infections in relation to host biology and season over a 2 yr period. In addition, we tested a range of host tissues and organs to gain more information on the host-parasite interaction. The parasite was present in all tissues and organs investigated, including the gonad and eggs of a berried female. Parasite prevalence was highest in the cuticular epithelium and hepatopancreas. Both annual and seasonal variation was found in parasite prevalence and parasite load. No difference was found in parasite prevalence or parasite load with either crab size or crab sex. Granulomas as a response to infection were significantly more abundant in infected velvet crab individuals. The results of this study provide important information on the host-parasite interaction between P. canceri and the velvet crab and highlight the importance of including parasite monitoring in the management of crustacean fisheries.

Shrimp classification for white spot syndrome detection through enhanced gated recurrent unit-based wild geese migration optimization algorithm.

The major dangerous viral infection for cultivated shrimps is WSSV. The virus is extremely dangerous, spreads swiftly, and may result in up to 100% mortality in 3-10days. The vast wrapped double stranded DNA virus known as WSSV describes a member of the Nimaviridae viral family's species Whispovirus. It impacts a variety of crustacean hosts but predominantly marine shrimp species that are raised for commercial purposes. The entire age groups are affected by the virus, which leads to widespread mortality. Mesodermal and ectodermal tissues, like the lymph nodes, gills, and cuticular epithelium, represents the centres of infection. Complete genome sequencing related to the WSSV strains from Thailand, China, and Taiwan has identified minute genetic variations amongst them. There exist conflicting findings on the causes of WSSV pathogenicity, which involve variations in the size associated with the genome, the count of tandem repeats, and the availability or lack of certain proteins. Hence, this paper plans to perform the shrimp classification for the WSSV on the basis of novel deep learning methodology. Initially, the data is gathered from the farms as well as internet sources. Next, the pre-processing of the gathered shrimp images is accomplished using the LBP technique. These pre-processed images undergo the segmentation process utilizing the TGVFCMS approach. The extraction of the features from these segmented images is performed by the PLDA technique. In the final step, the classification of the shrimp into healthy shrimp and WSSV affected shrimp is done by the EGRU, in which the parameter tuning is accomplished by the wild GMO algorithm with the consideration of accuracy maximization as the major objective function. Performance indicators for accuracy have been compared with those of various conventional methods, and the results show that the methodology is capable of accurately identifying the shrimp WSSV illness.

Fine structure of the female genital system of diving beetle Stictonectes optatus (Seidlitz, 1887) (Dytiscidae-Hydroporinae) and evidence of mating plug formation

The general organization of the female genital system of the diving beetle Stictonectes optatus was studied, clarifying the complex structure of the spermatheca and spermathecal gland. The two structures adhere closely to each other, sharing a small area of their cuticular epithelium. A long duct connects the bursa copulatrix to the spermatheca, where the sperm are stored. The sperm reach the common oviduct, where egg fertilization occurs, via a fertilization duct. The spermathecal gland cells have extracellular cisterns where secretions are stored. Thin ducts composed of duct-forming cells transport these secretions to the apical gland region and into the spermathecal lumen. Soon after mating, the bursa copulatrix is almost completely occupied by a plug secreted by the male accessory glands. The secretions of the bursa epithelium seem to contribute to plug formation. Later this plug becomes large and spherical, obstructing the bursa copulatrix.

MINERALIZATION OF TEETH ENAMEL AFTER ERUPTION

The aim: The paper was aimed at the study of the processes of mineralization of the enamel of the permanent tooth after its eruption. Materials and methods: To study the structure of the enamel of permanent teeth has been carried out using light and electron microscopy. The study of the process of the development of the primordia of the permanent teeth involved 10 culled puppies of 30-40 days of age. Microscopic, electron microscopic, immunohistochemical methods of research have been used to study the processes of histogenesis. Results: The studies show that in the postnatal period, the formation of the crown, externally covered with cuticular epithelium, marks the formation of the primordium of the permanent tooth at the follicle stage. After eruption of a tooth, different parts of its crown have three individual structural and functional barriers to enamel biomineralization. The first one is provided by the cuticular epithelium of the pitted areas of the crown, which ensures filtering of the salivary fluid from the protein deposit in the form of a pellicle. The second barrier is defined on the lateral and cuspidate surfaces of the enamel, where the cuticle is erased or poorly expressed. The third structural and functional barrier of enamel biomineralization is located in the cervical portion of teeth of different classes. Conclusions: Different areas of the enamel in the tooth crown have specific filtration barriers, which can be distinguished as follows: pit-and-fissure-and-groove, cuspidateand-approximal, and cervical barriers. The cuticle is poorly expressed or totally absent on the cusps of the tooth crowns in contrast to pitted areas.

DENTAL CROWN BIOMINERALIZATION DURING ITS HISTOGENESIS

The aim: Thepaper wasaimedat thestudyof thebiomineralization processesofa permanentdental crown in thepostnatal period of histogenesis. Materials and methods: The study involved 30 culled puppies aged 30-40 days. To study the histogenesis of the germs of the permanent tooth from the cuticular epithelium in the postnatal period microscopic, electron microscopic, immunohistochemical methods of study have been used. Results: The studies show that in the postnatal period, the maturation of the germ of a permanent tooth starts with the synthesis of cells of the cuticular epithelium of the organic stroma, capable of subsequent mineralization. Differentiation of the proameloblasts, located on the surface of the dental papillary mesenchyma, at the early stages of histogenesis, is strongly associated with the appearance of a specific protein taftelin. Origination of secretory ameloblasts, which produce the protein enamelin, triggers the process of secondary biomineralization of the enamel. The terminal processes of the secretory ameloblasts produce the protein in the form of layers that overlap each other at a certain angle. Such layering of the structures of enamel and dentin contributes to the S-shaped maturation of the hard tooth tissues, strengthening them considerably. At the follicle stage, maturation of the dental crown, coated with cuticular epithelium, occurs. Invaginations of the cuticular epithelium form a characteristic topography of the dental crown, and enamel projections are further formed by the ameloblasts. Epitheliocytes of the inner layer of the enamel organ have desmosomal connections that allow the filtration of the salivary fluid at the stage of the enamel trophism. Conclusions: The findings of the study suggest that, normally, due to the cuticular epithelium, filtration of the salivary fluid occurs with protein deposition on it and subsequent infiltration of the calcium salts into the subjacent enamel.

Susceptibility of Exopalaemon carinicauda to the Infection with Shrimp Hemocyte Iridescent Virus (SHIV 20141215), a Strain of Decapod Iridescent Virus 1 (DIV1).

In this study, ridgetail white prawns—Exopalaemon carinicauda—were infected per os (PO) with debris of Penaeus vannamei infected with shrimp hemocyte iridescent virus (SHIV 20141215), a strain of decapod iridescent virus 1 (DIV1), and via intramuscular injection (IM with raw extracts of SHIV 20141215. The infected E. carinicauda showed obvious clinical symptoms, including weakness, empty gut and stomach, pale hepatopancreas, and partial death with mean cumulative mortalities of 42.5% and 70.8% by nonlinear regression, respectively. Results of TaqMan probe-based real-time quantitative PCR showed that the moribund and surviving individuals with clinical signs of infected E. carinicauda were DIV1-positive. Histological examination showed that there were darkly eosinophilic and cytoplasmic inclusions, of which some were surrounded with or contained tiny basophilic staining, and pyknosis in hemocytes in hepatopancreatic sinus, hematopoietic cells, cuticular epithelium, etc. On the slides of in situ DIG-labeling-loop-mediated DNA amplification (ISDL), positive signals were observed in hematopoietic tissue, stomach, cuticular epithelium, and hepatopancreatic sinus of infected prawns from both PO and IM groups. Transmission electron microscopy (TEM) of ultrathin sections showed that icosahedral DIV1 particles existed in hepatopancreatic sinus and gills of the infected E. carinicauda from the PO group. The viral particles were also observed in hepatopancreatic sinus, gills, pereiopods, muscles, and uropods of the infected E. carinicauda from the IM group. The assembled virions, which mostly distributed along the edge of the cytoplasmic virogenic stromata near cellular membrane of infected cells, were enveloped and approximately 150 nm in diameter. The results of molecular tests, histopathological examination, ISDL, and TEM confirmed that E. carinicauda is a susceptible host of DIV1. This study also indicated that E. carinicauda showed some degree of tolerance to the infection with DIV1 per os challenge mimicking natural pathway.

Functional morphology and neuronal innervation of the prothoracic defence gland in Timema

AbstractTimema is the most basal genus of Phasmatodea and the sister group to the remaining stick and leaf‐insects (Euphasmatodea). An autapomorphy of all phasmids is the paired prothoracic exocrine defence glands. In this study, the anatomy and innervation of the defence glands in Timema petita and Timema chumash are described and compared with the data on Euphasmatodea. In all phasmids, the glands consist of a cuticular epithelium, a secretory epithelium and muscular fibres that compress the lumen. In Timematodea, the muscular part of the gland is less developed than in Euphasmatodea and the ejection of the defence secretion depends on the dorsal longitudinal neck muscles. On the neuroanatomical level, Timema petita and Timema chumash lack neurons that are involved in the independent contraction of the gland in euphasmids. In both studied species of Timema, neck muscles play an active role in the gland function which is not observed in any other phasmid. Considering the basal position of this genus, this supports the hypothesis that in euphasmids, the muscular part of the gland evolved from the dorsal longitudinal neck muscles. Additionally, the same nerves that innervate the dorsal longitudinal neck muscles in all Polyneoptera also innervate the defence glands in phasmids.

Morphology and fine organization of the spermatheca of Haplotropis brunneriana (Orthoptera: Pamphagidae)

We investigated the morphology and structure of spermatheca in Haplotropis brunneriana (Orthoptera: Pamphagidae) by light and electronic microscopy. The spermatheca can be subdivided into a tubular seminal receptacle and a multiple-coiled spermathecal tube, both of which are composed of cuticular intima, epithelium layer, basal lamina and muscle layer, from inside to outside. The cuticular intima is made up of a heterogeneous endocuticle, a homogeneous exocuticle and an epicuticle, but the proportion of exocuticle in intima of the seminal receptacle is larger than that of the spermathecal tube. The epithelium layer comprises epithelial cells, gland cells and duct cells. The ultrastructural features of the epithelial cells indicated that its function potentially includes support, secretion and absorption. The gland cells potentially fulfil a secretory role indicative of the abundance of mitochondria and microvilli. In gland cells, an extracellular cavity, showing region differences in the seminal receptacle and the spermathecal tube, was lined with microvillus border. The role of duct cell is responsible for forming the secretory ductules, which connect the extracellular cavity with the lumen of the spermatheca through the cuticular intima. These new data contribute to our understanding of the function of the spermatheca of H. brunneriana.

Digestive system formation during the metamorphosis and definitive organogenesis in Apostichopus japonicus

We studied the ultrastructure of the digestive system in late doliolaria, pentactula, and 1-month-old juvenile of the holothurian Apostichopus japonicus. In late doliolaria and pentactula, the digestive system is divided into three segments: pharynx, gut, and cloaca. Pharynx and the posterior part of cloaca are lined by cuticular epithelium and apparently of ectodermal origin. The anterior part of cloaca and the entire gut is not differentiated histologically and is lined by a single type of digestive cells, vesicular enterocytes I. These cells are characterized by large secretory granules, containing an acidic substance, found in cytoplasm. As the anterior part of the cloaca is lined by cells typical of the endodermal segment of digestive tube (vesicular enterocytes I), we suggest this part to be of endodermal origin and probably formed from the larval stomach. In 1-month-old juveniles, the structure of the digestive system grows more complicated. In addition to vesicular enterocytes I, three more types of enterocytes appear in luminal epithelium. The specific distribution of the four types of digestive cells divides the intestine into three parts, each probably performing its own function. All enterocytes develop long microvilli, which indicate the intensification of the extracellular digestion processes and an increased absorption of dissolved nutrients.

Exoskeletons across the Pancrustacea: Comparative Morphology, Physiology, Biochemistry and Genetics

The exoskeletons of pancrustaceans, as typified by decapod crustaceans and insects, demonstrate a high degree of similarity with respect to histology, ultrastructure, function, and composition. The cuticular envelope in insects and the outer epicuticle in crustaceans both serve as the primary barrier to permeability of the exoskeleton, preventing loss of water and ions to the external medium. Prior to and following ecdysis, there is a sequence of expression and synthesis of different proteins by the cuticular epithelium for incorporation into the pre-exuvial and post-exuvial procuticle of insects and the exocuticle and endocuticle of crustaceans. Both exhibit regional differences in cuticular composition, e.g., the articular (intersegmental) membranes of insects and the arthrodial (joint) membranes of crustaceans. The primary difference between these cuticles is the ability to mineralize. Crustaceans' cuticles express a unique suite of proteins that provide for the nucleation and deposition of calcium carbonate. Orthologs of genes discussed in the present review were mined from a recently completed cuticular transcriptome of the crayfish, Cherax quadricarinatus, providing new insights into the nature of these proteins.

A histological variant of white spot syndrome virus (WSSV) from the Kingdom of Saudi Arabia

White spot syndrome virus (WSSV) is highly pathogenic to penaeid shrimp. The major targets of WSSV infection are tissues of ectodermal and mesodermal embryonic origin, predominantly the cuticular epithelium and subcuticular connective tissues. Recently, we discovered a WSSV variant in Penaeus indicus that heavily infects the subcuticular connective tissue, with very slight indications in the cuticular epithelium. The variant was also unusual in that WSSV accumulations were found in the interstitial spaces of both the subcuticular connective tissue and the lymphoid organ. This WSSV variant was confirmed through immunohistochemistry with an anti-WSSV VP28 monoclonal antibody, and also by in situ hybridization with a VP28 DNA probe. By in situ hybridization, shrimp with variant and typical histology were shown a deletion in ORF94, which is characteristic of a new type of WSSV found in Saudi Arabia; apparently, the loss of this ORF is not associated with the variant’s reduced capability of infecting the cuticular epithelium cells.

The structure of the fruit peel in two varieties of Malus domestica Borkh. (Rosaceae) before and after storage

The structure of fruit peel of two apple varieties ‘Szampion’ and ‘Jonagold’ was investigated using light microscopy as well as scanning and transmission electron microscopy. The samples were taken immediately after harvest and after 6-month controlled atmosphere storage. The Szampion and Jonagold fruit differed in terms of the surface type, number of lenticels, thickness of the cuticular epithelium, height of epidermal cells and thickness of the hypodermis as well as the amount of crystalline wax and the number of microcracks formed on the fruit surface. The 6-month storage resulted in fruit weight loss, increased numbers and depth of microcracks, thickening of the amorphous wax layer and enhanced production of platelet forms of crystalline wax, which filled the microcracks abundantly. Compared with Jonagold, the Szampion fruit exhibited a fewer lenticels, a bigger number of microcracks, smaller amounts of crystalline wax and more substantial weight loss. The apple varieties studied had a reticulate–lamellate cuticle, and at harvest, the epidermal and hypodermal cells contained numerous amyloplasts filled with starch grains, which were not found after the storage period. Additionally, after storage, the cell protoplasts in the apple peel displayed a disorganised structure, and their vacuoles contained fragments of cell membranes, intravacuolar precipitates and deposits, and spherical bodies. The results may facilitate better understanding of changes occurring in fruits of Szampion and Jonagold during storage and help choose the best storage conditions to reduce loss of weight and prevent impairment of fruit quality.

Biology, Host Range, Pathogenesis and Diagnosis of White spot syndrome virus

White spot syndrome virus (WSSV) is the most serious viral pathogen of cultured shrimp. It is a highly virulent virus that can spread quickly and can cause up to 100% mortality in 3-10days. WSSV is a large enveloped double stranded DNA virus belonging to genus Whispovirus of the virus family Nimaviridae. It has a wide host range among crustaceans and mainly affects commercially cultivated marine shrimp species. The virus infects all age groups causing large scale mortalities and the foci of infection are tissues of ectodermal and mesodermal origin, such as gills, lymphoid organ and cuticular epithelium. The whole genome sequencing of WSSV from China, Thailand and Taiwan have revealed minor genetic differences among different strains. There are varying reports regarding the factors responsible for WSSV virulence which include the differences in variable number of tandem repeats, the genome size and presence or absence of different proteins. Aim of this review is to give current information on the status, host range, pathogenesis and diagnosis of WSSV infection.

Presença do vírus da síndrome da mancha branca em crustáceos decápodes silvestres em lagoas costeiras no Sul do Brasil

A presença do vírus da síndrome da mancha branca (em inglês WSSV) nas principais espécies de camarões, siris e caranguejos de cinco lagoas que recebem o efluente de fazendas afetadas pela enfermidade foi detectada por nested PCR, e inclusões virais nos camarões por histologia. Pela nested PCR encontrou-se a presença de WSSV em 13 de 16 (81,2%) amostras de camarões da espécie Farfantepenaeus paulensis, em 13 de 14 (92,8%) de Litopenaeus schmitti, em uma de duas de Farfantepenaeus brasiliensis (50%), em 13 de 15 (86,6%) de siri da espécie Callinectes danae e em 11 de 12 (91,6%) de Callinectes sapidus, e não foi detectada no caranguejo Chasmagnathus granulata em 10 amostras. Inclusões características de WSSV foram observadas em três amostras histológicas de 50 (6,0%) no epitélio gástrico e cuticular e nas brânquias de dois exemplares de F. paulensis e um de L. schmitti. É o primeiro relato da presença de WSSV em camarões L. schmitti e no siri C. danae silvestres. As principais espécies de camarões e siris dos ambientes de entorno das fazendas foram contaminadas pelo WSSV, constituindo-se em vetores potenciais do vírus.

Characteristics of the surface of the epidermis in floral nectaries and the receptacle of mountain ash (Sorbus aucuparia L.)

The structure of receptacular surfaces of floral nectaries at two flowering stages and the structure of the outer surface of the receptacle of <i>Sorbus aucuparia</i> were investigated using scanning electron microscopy. Changes in the development of the cuticular epithelium of the nectary epidermis and differences in the degree of aperture of stomata were observed. Increased undulation of the gland surface was found during flower development. Numerous stomata were situated slightly below the level of epidermal cells of the nectary. At the pollination stage, open pores or pores surrounded by the cuticular epithelium were observed, as well as covered by dried secretion. Dried nectar in the form of patches was also visible on the surface of the gland. Stomata of the outer surface of the receptacle were located on protrusions and surrounded by the cuticular epithelium.

Parasitization by Macrocentrus cingulum (Hymenoptera: Braconidae) influences expression of prophenoloxidase in Asian corn borer Ostrinia furnacalis

A prophenoloxidase (PPO) cDNA (OfPPO) was cloned from the Asian corn borer Ostrinia furnacalis. Sequence analysis revealed a full length transcript of the OfPPO cDNA with 2,686 bp, containing a 2,079 bp open reading frame (ORF), a 73-bp 5'-untranslated region, and a 534-bp 3'-untranslated region with a poly(A) signal. The ORF encodes a 693-amino acid polypeptide, containing two distinct copper-binding regions, a plausible thiol ester site, two proteolytic activation sites, and a conserved C-terminal region, but lacks a signal peptide sequence. Expression of the OfPPO transcript in the plasma, hemocytes, fat body and midgut was inhibited by Macrocentrus cingulum at 4 h post-parasitization (pp). In situ hybridization analysis showed that the hemocytes, especially the oenocytoids, hybridized strongly with the DNA probes of the OfPPO gene. No signal was detected in the cuticular epithelium or fat body of the parasitized larvae. Colloidal gold particles were used to visualize the PPO by immunoelectron microscopy. The time course study revealed a decrease in the labeling of the OfPPO at 4, 6, 8, 12, and 1 day pp in the larval integument and midgut parasitized by M. cingulum. We infer from time course studies of OfPPO gene expression and PO enzymatic activity that OfPPO in the integument is released from hemocytes and that the OfPPO expression was influenced at the transcriptional, translational, and then the post-translational level by parasitization challenge.

Seawater ozonation and formalin disinfection for the larval culture of eastern rock lobster, Jasus ( Sagmariasus) verreauxi, phyllosoma

The effects of seawater disinfection with continuous ozonation or with daily formalin treatment during flow-through culture, on the survival, growth, bacteriology and histology of eastern rock lobster, Jasus ( Sagmariasus) verreauxi, phyllosoma were determined. Survival from hatch to Instar II was highest and bacterial abundance was least in low ozonated seawater (containing 5 ppb ionised bromine, Br). By contrast, at high ozonation (45 ppb Br) and medium ozonation (15 ppb Br), 77% and 69% of larvae, respectively, suffered deformities at the moult to Instar II and starved to death. Histological examination of phyllosoma showed no differences in cuticular epithelium thickness but the digestive gland tissue of moribund deformed phyllosoma had significantly thinner tubule epithelium, the lumen was dilated, B-cells were more abundant and there was greater separation between the cuticular epithelium and distal tip of digestive gland tubules. In unozonated (Control) water, 66% of larvae died during Instar II probably resulting from a possible Vibrio infection. In a second experiment, survival to Instar III was highest at low ozonation or no ozonation without addition of formalin (0 ppm). Bacterial numbers were lowest in low ozonation with 0 ppm formalin treatments, compared to daily treatment with formalin at 10 ppm or above. A concentration of 250 ppm formalin killed all larvae by Instar III. In a final experiment, larval survival between Instar III to VI in low ozonated seawater was approximately 80% at formalin levels of 0 to 80 ppm, whereas all larvae treated with 160 ppm formalin died shortly after Instar V. Disinfection improved survival by minimising bacterial disease for the culture of phyllosoma to Instar VI without interrupting growth and development. The present study established that the optimum treatment for the culture of phyllosoma to Instar VI appeared to be low ozonation (5 ppb Br) with 10 ppm formalin.

Protective effect of oleanolic acid on gentamicin induced nephrotoxicity in rats

Oleanolic acid is a molecule of current therapeutic interest. In the present study, oleanolic acid isolated from the cuticular epithelium of Viscum articulatum Burm. f. (Viscaceae) was investigated for its protective effects on gentamicin-induced renal damage in rats. Nephrotoxicity was induced in rats by intraperitoneal injection of gentamicin at a dose of 100 mg/kg/day for 8 days. The effect of Oleanolic acid administered orally at doses 40, 60 and 80 mg/kg/day was assessed biochemically by determination of albumin, urea and creatinine in serum and urine samples and also through histopathological examination of the kidneys. Oleanolic acid protected the rat kidneys from gentamicin-induced nephrotoxicity as evident from a decrease in the serum and urine levels of creatinine, albumin and urea. Oleanolic acid also protected the rat kidneys from histological alterations induced by gentamicin and also improved the glomerular filtration rate. Compared with an earlier report on intraperitoneal administration of oleanolic acid in paracetamol-induced nephrotoxicity in rats, the data show that orally administered oleanolic acid also exerted a nephroprotective effect even in the case of a nephrotoxicant such as gentamicin, which directly deteriorates the kidney function without prior metabolism.

Tranosema rostrale ichnovirus repeat element genes display distinct transcriptional patterns in caterpillar and wasp hosts

The endoparasitic wasp Tranosema rostrale transmits an ichnovirus to its lepidopteran host, Choristoneura fumiferana, during parasitization. As shown for other ichnoviruses, the segmented dsDNA genome of the T. rostrale ichnovirus (TrIV) features several multi-gene families, including the repeat element (rep) family, whose products display no known similarity to non-ichnovirus proteins, except for a homologue encoded by the genome of the Helicoverpa armigera granulovirus; their functions remain unknown. This study applied linear regression of efficiency analysis to real-time PCR quantification of transcript abundance for all 17 TrIV rep open reading frames (ORFs) in parasitized and virus-injected C. fumiferana larvae, as well as in T. rostrale ovaries and head-thorax complexes. Although transcripts were detected for most rep ORFs in infected caterpillars, two of them clearly outnumbered the others in whole larvae, with a tendency for levels to drop over time after infection. The genome segments bearing the three most highly expressed rep genes in parasitized caterpillars were present in higher proportions than other rep-bearing genome segments in TrIV DNA, suggesting a possible role for gene dosage in the regulation of transcription level. TrIV rep genes also showed important differences in the relative abundance of their transcripts in specific tissues (cuticular epithelium, the fat body, haemocytes and the midgut), implying tissue-specific roles for individual members of this gene family. Significantly, no rep transcripts were detected in T. rostrale head-thorax complexes, whereas some were abundant in ovaries. There, the transcription pattern was completely different from that observed in infected caterpillars, suggesting that some rep genes have wasp-specific functions.