Lennart Ohlsson

Postembryonic development of Arg-Phe-amide-like and cholecystokinin-like immunoreactive neurons in the blowfly optic lobe

SummaryThe adult optic lobes of the blowfly Calliphora erythrocephala were found to be innervated by more than 2000 neurons immunoreactive to antisera raised against the neuropeptides FMRFamide, its fragment RFamide, and gastrin/cholecystokinin (CCK). All of the CCK-like immunoreactive (CCK-IR) neurons also reacted with antisera to RFamide, FMRFamide and pancreatic polypeptide. A few RFamide/FMRFamide-like immunoreactive (RF-IR) neurons did not react with CCK antisera; they reacted instead with antisera to Leu-enkephalin and Met-enkephalin-Arg6-Phe7. The RF-IR neurons are, thus, heterogeneous with respect to their contents of immunoreactive peptides. Two of the RF-IR neuron types innervating the adult optic lobes could be traced in their entirety only after following their postembryonic development, because of the complexity of the trajectories of the immunoreactive neuronal process in the adult insect. The majority of the cell bodies of the RF-IR and CCK-IR neurons lie within the optic lobes and are derived from imaginal neuroblasts of the inner and outer optic anlagen. Six of the peptidergic neurons are, however, metamorphosing larval neurons with their cell bodies in the central part of the protocerebrum. The full extent of immunoreactivitiy is not attained in some of the neurons until the late pupal or early adult stage. The larval optic center was also found to be innervated by neurons immuno-reactive with both RFamide and CCK antisera. The cell bodies of these RF-IR/CCK-IR neurons are located near the developing lamina (one on each side). In the 24 h pupa, the cell bodies of these neurons are still immunoreactive, but thereafter they cannot be immunolabeled apparently due to cell death or a change in transmitter phenotype.

Implementing an embedded GPU language by combining translation and generation

Dynamic languages typically allow programs to be written at a very high level of abstraction. But their dynamic nature makes it very hard to compile such languages, meaning that a price has to be paid in terms of performance. However under certain restricted conditions compilation is possible. In this paper we describe how a domain specific language for image processing in Python can be compiled for execution on high speed graphics processing units. Previous work on similar problems have used either translative or generative compilation methods, each of which has its limitations. We propose a strategy which combine these two methods thereby achieving the benefits of both.

Postembryonic development of serotonin-immunoreactive neurons in the central nervous system of the blowfly, Calliphora erythrocephala

SummaryThe postembryonic development of serotonin-immunoreactive (5-HTi) neurons was studied in the optic lobe of the blowfly. In the adult fly there are 24 5-HTi neurons invading each optic lobe. The perikarya of two of these neurons are situated in the dorso-caudal part of the protocerebrum (LBO-5HT neurons; large bilateral optic lobe 5-HTi neurons). The cell bodies of the remaining 22 neurons are located anteriorly at the medial base of the medulla (2 innervating the lobula, LO-5HT neurons; and 20 neurons innervating the medulla, ME-5HT neurons). The two central neurons (LBO-5HT neurons) are derived from metamorphosing larval neurons, while the ME- and LO-5HT neurons are imaginai optic lobe neurons differentiating during pupal development.The 5-HTi neurons of the optic lobe seem to have different ancestors. The LBO-5HT neurons are probably derived from segmental protocerebral neuroblasts, whereas the ME-and LO-5HT neurons are most likely derived from the inner optic anlage. The first 5-HTi fibers to reach the imaginal optic lobes are seen in the late third instar larva and are derived from the LBO-5HT neurons. The first ME- and LO-5HT neurons become immunoreactive at 24 h (10%) pupal development. At about 96 h (40%) of pupal development all the 5-HTi neurons of the optic lobes have differentiated and attained their basic adult morphology. The further development mainly entails increase in volume of arborizations and number of finer processes. The differentiation and outgrowth of 5-HTi processes follows that of, e.g., columnar neurons in the optic lobe neuropils. Hence, 5-HTi processes invade neuropil relatively late in the differentiation of the optic lobe.

Immunocytochemical detection of the carbohydrate antigen, Sialyl Lewisx, in normal human skin and during irritant contact dermatitis

Abstract Sialys Lewisx (SLex) is a ligand for the E‐selectin and the interaction of E‐selectin on the endothelium and SLex on T cells may be important for T‐cell migration into the skin. We investigated the expression of SLex on Langerhans cells (LC) in normal skin and on LC repopulating epidermis deprived of LC due to a preceding irritant contact dermatitis. SLex was visualized by fluorescence and light microscopic immunocytochemistry using the monoclonal antibody. CSLEX‐1. The results showed that about 40% of LC in normal epidermis express SLex. In the repopulation phase, most of the epidermal cells were CDla+/SLex+. We suggest that SLex is present on epidermal LC that have recently immigrated from the dermis.

Matrix multiplication on LUCAS

Multiplication of two N by N matrices involves N3 multiplications of elements. The task allows a large amount of parallelism to be utilized, indicating that it can be efficiently executed on a parallel computer. This paper describes how matrix multiplication is performed on LUCAS, an SIMD type parallel processor with bit-serial processing elements. The interconnection network is of Perfect Shuffle/Exchange type. The case of study is when the number of processing elements is between N2 and N3. The algorithm presented can be applied to any computer with the same interconnection structure. Formulas showing how the execution time depends on data length and matrix size are presented together with measured values from execution on LUCAS.