First description of the immature stages of Fannia sabroskyi Seago, 1954 (Insecta, Diptera, Fanniidae).

Egg, larvae and the puparium of Fannia sabroskyi Seago, 1954 (Diptera, Fanniidae) are described and illustrated for the first time. The following structures have been documented: pseudocephalon, antennal complex, maxillary palpus, facial mask, anterior spiracle, cephaloskeleton structures, thoracic and abdominal processes, anal division, and posterior spiracle. Due to its necrophagous habit, this species may be of potential forensic importance for estimating the postmortem interval in criminal investigations. The information presented herein may be useful to distinguish the immature forms of Fannia species and to supplement the database for identification of Neotropical species of Fanniidae. In addition, it is also important for evolutionary and phylogenetic studies.

[Visualization of chromosome territories in interphase nuclei of ovarian nurse cells in Calliphora erythrocephala Mg. (Diptera: Calliphoridae)].

Analysis of localization of chromosomes 2, 3, and 6 of Calliphora erythrocephala Mg. in ovarian nurse cell nuclei with different chromatin structure has shown that the regions of DNA probe hybridization reduced with increasing chromatin compaction. Hybridization of DNA probes of chromosomes 3 and 6 to secondary reticular nuclei demonstrated that chromosomes retain their territories in the nuclei when the chromatin acquires a reticular structure. These results suggest regular organization of the chromosomal apparatus at all stages of the endomitotic cycle, including the stage of highly polyploid reticular nuclei. FISH of DNA probe of the chromosome 2 telomeric region to secondary reticular nuclei revealed a peripheral distribution of the signal. Zones of more intensive DNA probe hybridization have been distinguished. These zones probably are the regions of accumulation of telomeric and (or) centromeric chromosome regions.

Development of PDF-immunoreactive cells, possible clock neurons, in the housefly Musca domestica.

Even though the housefly Musca domestica shows clear circadian rhythms in its behavioural and physiological processes, a circadian pacemaker system controlling these rhythms has not yet been described morphologically in this species. In M. domestica, neurons immunoreactive to pigment-dispersing factor (PDF), a neurotransmitter/neuromodulator of circadian information arising from a circadian clock and transmitted to target cells, are similar in their number and distribution to the PDF neurons of Drosophila melanogaster. In D. melanogaster these neurons co-localize PER protein and have been identified as clock neurons in that species. Here we report PDF-immunoreactive cells in the housefly's brain during postembryonic development in the larval and pupal stages, as well as in the adult fly soon after eclosion. In the housefly's brain, there are three groups of PDF-immunoreactive neurons: two groups with small (sPDFMe) and large (lPDFMe) cell bodies in the proximal medulla of the optic lobe; and one group in the dorsal protocerebrum (PDFD). Three out of four sPDFMe can be detected during the first hour of larval development, but the fourth sPDFMe is observed in the larva only from 48 hours after hatching, along with five lPDFMe neurons, seen first as two subgroups, and three out of four PDFD neurons. During postembryonic development these neurons show changes in their structure and immunoreactivity. New PDF neurons are observed during pupal development but these neurons mostly do not survive into adulthood. In the adult fly's brain, the PDF neurons have also been examined in double-labelled preparations made with a second antibody directed against the product of one of several clock genes: period (per), timeless (tim), or cryptochrome (cry). Among them, only immunoreactivity to CRY-like protein has been detected in the brain of M. domestica and has shown a daily rhythm in its concentration, as examined immunocytochemically. CRY was co-localized with PDF in the sPDFMe of the housefly's brain fixed during the day. The possibility that the sPDFMe neurons are the housefly's clock neurons is discussed.

Cytochemical studies of oocyte development in Sarcophaga lineatocollis Macq. (Muscidae: Diptera).

The ovary of Sarcophaga lineatocollis is a typical polytrophic ovary. Each of its 25-30 ovarioles is composed of a small terminal filament, a small germarium and a vitellarium consisting of the egg follicle. The tunica propria is a noncellular, PAS-positive membrane. The ovarian follicle contains fifteen trophocytes and one oocyte. RNA is synthesized with the aid of the nuclei in the trophocyte cytoplasm, which are RNA- and PAS-positive. Protein is deposited intensively in the early stages of the trophocytes. The trophocytes of Sarcophaga lineatocollis synthesize RNA and protein more actively than the oocyte. In this fly, protein yolk precursor (PYP) bodies are supplied by the trophocyte cytoplasm to the ooplasm at an advanced stage of development. Nucleolar budding and vacuolation are observed in the trophocytes. RNA, DNA, protein and PYP bodies appear to be transported to the ooplasm from the trophocytes. Pyknotic trophocyte nuclei can be seen entering the ooplasm. The perinuclear Golgi bodies of the trophocytes help in the production and maturation of PYP bodies in the trophocytes before they are organized and passed on to the oocytes. Some RNA is contributed to the oocyte by the follicular epithelium. All these processes leading to maturation and development of the oocyte are discussed and interpreted.